# Image noise

(Redirected from Image Noise)
Image noise
You are encouraged to solve this task according to the task description, using any language you may know.

Generate a random black and white   320x240   image continuously, showing FPS (frames per second).

A sample image

## 6502 Assembly

Works with: [Easy6502]

Easy6502's built-in RNG allows for random pixels to be displayed in an infinite loop. Unfortunately these pixels are far too large to effectively display an FPS counter, although the unused Y register in the program below could theoretically output that.

```define sysRandom \$fe

Snow:
lda sysRandom  ;get a random number
and #\$01       ;remove all but bit 0
sta \$0200,x    ;store in first section of VRAM

lda sysRandom  ;get a random number
and #\$01       ;remove all but bit 0
sta \$0300,x    ;store in second section of VRAM

lda sysRandom  ;get a random number
and #\$01       ;remove all but bit 0
sta \$0400,x    ;store in third section of VRAM

lda sysRandom  ;get a random number
and #\$01       ;remove all but bit 0
sta \$0500,x    ;store in last section of VRAM

inx            ;next X
jmp Snow       ;loop forever```

## Action!

```INCLUDE "D2:REAL.ACT" ;from the Action! Tool Kit

DEFINE TEXT_SIZE="40"
BYTE ARRAY text(TEXT_SIZE)

CARD FUNC GetFrame()
BYTE RTCLOK1=\$13,RTCLOK2=\$14
CARD res
BYTE lsb=res,msb=res+1

lsb=RTCLOK2
msb=RTCLOK1
RETURN (res)

PROC CalcFPS(CARD frames REAL POINTER fps)
BYTE PALNTSC=\$D014
REAL ms,r1000

IF PALNTSC=15 THEN
frames==*60
ELSE
frames==*50
FI

IntToReal(1000,r1000)
IntToReal(frames,ms)
RealDiv(r1000,ms,fps)
RETURN

PROC FillNoise()
BYTE POINTER ptr
BYTE x,y,rnd=\$D20A

ptr=PeekC(88)
FOR y=0 TO 191
DO
FOR x=0 TO 39
DO
ptr^=rnd
ptr==+1
OD
OD
RETURN

PROC PrepareScreen()
BYTE COLOR1=\$02C5,COLOR2=\$02C6
CARD SDLSTL=\$0230,ptr
BYTE i,v
BYTE ARRAY dlist(205)

Graphics(8+16)
COLOR1=\$0F
COLOR2=\$00

;prepare text
FOR i=0 TO TEXT_SIZE-1
DO
text(i)=0
OD
text(6)='F-32
text(7)='P-32
text(8)='S-32

;modify display list to add one row with text on the top
dlist(0)=\$70
dlist(1)=\$70
dlist(2)=\$42
PokeC(dlist+3,text)

ptr=SDLSTL
ptr==+3
FOR i=5 TO 202
DO
dlist(i)=Peek(ptr)
ptr==+1
OD
PokeC(dlist+203,dlist)

SDLSTL=dlist
RETURN

PROC PrintFPS(REAL POINTER fps)
CHAR ARRAY tmp(20)
BYTE i

StrR(fps,tmp)
FOR i=1 TO 5
DO
text(i-1)=tmp(i)-32
OD
RETURN

PROC Main()
BYTE CH=\$02FC
CARD beg,end
REAL fps

PrepareScreen()
beg=GetFrame()
DO
FillNoise()
end=GetFrame()
CalcFPS(end-beg,fps)
PrintFPS(fps)
beg=end
UNTIL CH#\$FF
OD
CH=\$FF
RETURN```
Output:

Library: Lumen

```with Lumen.Image;

package Noise is

function Create_Image (Width, Height : Natural) return Lumen.Image.Descriptor;

end Noise;
```

```with Ada.Numerics.Discrete_Random;

package body Noise is
type Color is (Black, White);
package Color_Random is new Ada.Numerics.Discrete_Random (Color);
Color_Gen : Color_Random.Generator;

function Create_Image (Width, Height : Natural) return Lumen.Image.Descriptor is
Result : Lumen.Image.Descriptor;
begin
Color_Random.Reset (Color_Gen);
Result.Width := Width;
Result.Height := Height;
Result.Complete := True;
Result.Values := new Lumen.Image.Pixel_Matrix (1 .. Width, 1 .. Height);
for X in 1 .. Width loop
for Y in 1 .. Height loop
if Color_Random.Random (Color_Gen) = Black then
Result.Values (X, Y) := (R => 0, G => 0, B => 0, A => 0);
else
Result.Values (X, Y) := (R => 255, G => 255, B => 255, A => 0);
end if;
end loop;
end loop;
return Result;
end Create_Image;

end Noise;
```

```with Ada.Calendar;
with Lumen.Window;
with Lumen.Image;
with Lumen.Events.Animate;
with GL;
with Noise;

procedure Test_Noise is
package Float_IO is new Ada.Text_IO.Float_IO (Float);

Program_End : exception;

Win : Lumen.Window.Handle;
Image : Lumen.Image.Descriptor;
Tx_Name : aliased GL.GLuint;
Wide : Natural := 320;
High : Natural := 240;
Frame_Count : Natural := 0;

-- Create a texture and bind a 2D image to it
procedure Create_Texture is
use GL;

package GLB is new System.Address_To_Access_Conversions (GLubyte);

IP : GLpointer;
begin  -- Create_Texture
-- Allocate a texture name
glGenTextures (1, Tx_Name'Unchecked_Access);

-- Bind texture operations to the newly-created texture name
glBindTexture (GL_TEXTURE_2D, Tx_Name);

-- Select modulate to mix texture with color for shading
glTexEnvi (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);

-- Wrap textures at both edges
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

-- How the texture behaves when minified and magnified
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

-- Create a pointer to the image.  This sort of horror show is going to
-- be disappearing once Lumen includes its own OpenGL bindings.

-- Build our texture from the image we loaded earlier
glTexImage2D (GL_TEXTURE_2D, 0, GL_RGBA, GLsizei (Image.Width), GLsizei (Image.Height), 0,
GL_RGBA, GL_UNSIGNED_BYTE, IP);
end Create_Texture;

-- Set or reset the window view parameters
procedure Set_View (W, H : in Natural) is
use GL;
begin  -- Set_View
GL.glEnable (GL.GL_TEXTURE_2D);
glClearColor (0.8, 0.8, 0.8, 1.0);

glMatrixMode (GL_PROJECTION);
glViewport (0, 0, GLsizei (W), GLsizei (H));
glOrtho (0.0, GLdouble (W), GLdouble (H), 0.0, -1.0, 1.0);

glMatrixMode (GL_MODELVIEW);
end Set_View;

-- Draw our scene
procedure Draw is
use GL;
begin  -- Draw
-- clear the screen
glClear (GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);
GL.glBindTexture (GL.GL_TEXTURE_2D, Tx_Name);

-- fill with a single textured quad
begin
glTexCoord2f (1.0, 0.0);
glVertex2i (GLint (Wide), 0);

glTexCoord2f (0.0, 0.0);
glVertex2i (0, 0);

glTexCoord2f (0.0, 1.0);
glVertex2i (0, GLint (High));

glTexCoord2f (1.0, 1.0);
glVertex2i (GLint (Wide), GLint (High));
end;
glEnd;

-- flush rendering pipeline
glFlush;

-- Now show it
Lumen.Window.Swap (Win);
end Draw;

-- Simple event handler routine for keypresses and close-window events
procedure Quit_Handler (Event : in Lumen.Events.Event_Data) is
begin  -- Quit_Handler
raise Program_End;
end Quit_Handler;

-- Simple event handler routine for Exposed events
procedure Expose_Handler (Event : in Lumen.Events.Event_Data) is
pragma Unreferenced (Event);
begin  -- Expose_Handler
Draw;
end Expose_Handler;

-- Simple event handler routine for Resized events
procedure Resize_Handler (Event : in Lumen.Events.Event_Data) is
begin  -- Resize_Handler
Wide := Event.Resize_Data.Width;
High := Event.Resize_Data.Height;
Set_View (Wide, High);
Draw;
end Resize_Handler;

procedure Next_Frame (Frame_Delta : in Duration) is
pragma Unreferenced (Frame_Delta);
begin
Frame_Count := Frame_Count + 1;
if Ada.Calendar.Clock >= First_Frame + 1.0 then
Float_IO.Put (Float (Frame_Count), 5, 1, 0);
Frame_Count := 0;
end if;
Image := Noise.Create_Image (Width => Wide, Height => High);
Create_Texture;
Draw;
end Next_Frame;
begin
-- Create Lumen window, accepting most defaults; turn double buffering off
-- for simplicity
Lumen.Window.Create (Win           => Win,
Name          => "Noise fractal",
Width         => Wide,
Height        => High,
Events        => (Lumen.Window.Want_Exposure  => True,
Lumen.Window.Want_Key_Press => True,
others                      => False));

-- Set up the viewport and scene parameters
Set_View (Wide, High);

-- Now create the texture and set up to use it
Image := Noise.Create_Image (Width => Wide, Height => High);
Create_Texture;

-- Enter the event loop
declare
use Lumen.Events;
begin
Animate.Select_Events (Win   => Win,
Calls => (Key_Press    => Quit_Handler'Unrestricted_Access,
Exposed      => Expose_Handler'Unrestricted_Access,
Resized      => Resize_Handler'Unrestricted_Access,
Close_Window => Quit_Handler'Unrestricted_Access,
others       => No_Callback),
FPS   => Animate.Flat_Out,
Frame => Next_Frame'Unrestricted_Access);
end;
exception
when Program_End =>
null;
end Test_Noise;
```

## Axe

Note that since the calculator's screen is 96x64, this example uses those dimensions instead of 320x240.

Instead of naively drawing each pixel to the screen, this implementation directly writes random numbers to the buffer, which randomly sets each pixel. Because Axe does not have native clock support, the FPS counter is simulated by counting "ticks" at the known interrupt rate of 107.79 Hz (rounded to 108).

It is possible to notice some vertical line patterns in the noise. This is likely due to the pseudorandom number generator and not the drawing method.

This example gets steady 48 FPS on a TI-84 Plus Silver Edition running at 15 MHz. It gets 26 FPS when running at 6 MHz. Some pixels appear gray because the duration of each frame is shorter than the screen's notoriously slow response time. If a pixel is toggled very quickly, it never has time to fully transition to white or black.

```.Enable 15 MHz full speed mode
Full
.Disable memory access delays (adds 1 FPS)
Fullʳ

.Flush key presses
While getKey(0)
End

.Setup
0→F
0→N
Fix 5
fnInt(FPS,6)

Repeat getKey(0)
NOISE()
F++
.Reset the FPS counter before it overflows
F>606?0→F→N
Text(0,0,F*108/N▶Dec)
DispGraph
End

.Clean up
LnRegʳ
Fix 4
Return

.Draws random noise to the buffer
Lbl NOISE
ClrDraw
For(I,0,5)
For(J,0,63)
rand→{J*12+(I*2)+L₆}ʳ
End
End
Return

.Increments the tick counter
Lbl FPS
N++
Return```

## BBC BASIC

```      dx% = 320
dy% = 240
images% = 100000
VDU 23,22,dx%;dy%;8,8,16,0

REM Create a block of random data in memory:
DIM random% dx%*dy%+images%
FOR R% = random% TO random%+dx%*dy%+images%
?R% = RND(256)-1
NEXT

REM Create a BMP file structure:
DIM bmpfile{bfType{l&,h&}, bfSize%, bfReserved%, bfOffBits%, \
\   biSize%, biWidth%, biHeight%, biPlanes{l&,h&}, biBitCount{l&,h&}, \
\   biCompression%, biSizeImage%, biXPelsPerMeter%, biYPelsPerMeter%, \
\   biClrUsed%, biClrImportant%, biPalette%(255)}
bmpfile.biSize% = 40
bmpfile.biWidth% = dx%
bmpfile.biHeight% = dy%
bmpfile.biPlanes.l& = 1
bmpfile.biBitCount.l& = 8
FOR C% = 0 TO 255
bmpfile.biPalette%(C%) = C% OR C%<<8 OR C%<<16
NEXT

REM Display image at a random offset into the data:
frame% = 0
TIME = 0
REPEAT
bmpfile.bfOffBits% = random% - bmpfile{} + RND(images%)
OSCLI "MDISPLAY " + STR\$~bmpfile{}
frame% += 1
IF TIME>10 THEN
SYS "SetWindowText", @hwnd%, "BBC BASIC: " + STR\$(frame%*100 DIV TIME) + " fps"
ENDIF
UNTIL FALSE
```

## C

Translation of: OCaml
Library: SDL
```#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <SDL/SDL.h>

unsigned int frames = 0;
unsigned int t_acc = 0;

void print_fps ()
{
static Uint32 last_t = 0;
Uint32 t = SDL_GetTicks();
Uint32 dt = t - last_t;
t_acc += dt;
if (t_acc > 1000)
{
unsigned int el_time = t_acc / 1000;
printf("- fps: %g\n",
(float) frames / (float) el_time);
t_acc = 0;
frames = 0;
}
last_t = t;
}

void blit_noise(SDL_Surface *surf)
{
unsigned int i;
long dim = surf->w * surf->h;
while (1)
{
SDL_LockSurface(surf);
for (i=0; i < dim; ++i) {
((unsigned char *)surf->pixels)[i] = ((rand() & 1) ? 255 : 0);
}
SDL_UnlockSurface(surf);
SDL_Flip(surf);
++frames;
print_fps();
}
}

int main(void)
{
SDL_Surface *surf = NULL;
srand((unsigned int)time(NULL));
SDL_Init(SDL_INIT_TIMER | SDL_INIT_VIDEO);
surf = SDL_SetVideoMode(320, 240, 8, SDL_DOUBLEBUF | SDL_HWSURFACE);
blit_noise(surf);
}
```

### Fast OpenGL method

Library: GLUT

Depending on your hardware, you might be able to get thousands of frames per second. Compiled with `gcc -lglut -lGL -g -Wall -O2`.

```#include <GL/glut.h>
#include <GL/gl.h>
#include <stdio.h>
#include <time.h>

#define W 320
#define H 240
#define slen W * H / sizeof(int)

time_t start, last;

void render()
{
static int frame = 0, bits[slen];
register int i = slen, r;
time_t t;

r = bits[0] + 1;
while (i--) r *= 1103515245, bits[i] = r ^ (bits[i] >> 16);

glClear(GL_COLOR_BUFFER_BIT);
glBitmap(W, H, 0, 0, 0, 0, (void*)bits);
glFlush();

if (!(++frame & 15)) {
if ((t = time(0)) > last) {
last = t;
printf("\rfps: %ld  ", frame / (t - start));
fflush(stdout);
}
}
}

int main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_INDEX);
glutInitWindowSize(W, H);
glutCreateWindow("noise");
glutDisplayFunc(render);
glutIdleFunc(render);

last = start = time(0);

glutMainLoop();
return 0;
}
```

## C#

Max 185 FPS on .NET 4.0/Windows 7 64-bit on Athlon II X4 620 - ATI Radeon X1200.

```using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Runtime.InteropServices;
using System.Windows.Forms;

class Program
{
static Size size = new Size(320, 240);
static Rectangle rectsize = new Rectangle(new Point(0, 0), size);
static int numpixels = size.Width * size.Height;
static int numbytes = numpixels * 3;

static PictureBox pb;
static BackgroundWorker worker;

static double time = 0;
static double frames = 0;
static Random rand = new Random();

static byte tmp;
static byte white = 255;
static byte black = 0;
static int halfmax = int.MaxValue / 2; // more voodoo! calling Next() is faster than Next(2)!

static IEnumerable<byte> YieldVodoo()
{
// Yield 3 times same number (i.e 255 255 255) for numpixels times.

for (int i = 0; i < numpixels; i++)
{
tmp = rand.Next() < halfmax ? black : white; // no more lists!

// no more loops! yield! yield! yield!
yield return tmp;
yield return tmp;
yield return tmp;
}
}

static Image Randimg()
{
// Low-level bitmaps
var bitmap = new Bitmap(size.Width, size.Height);
var data = bitmap.LockBits(rectsize, ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);

Marshal.Copy(
YieldVodoo().ToArray<byte>(),// source
0, // start
data.Scan0, // scan0 is a pointer to low-level bitmap data
numbytes); // number of bytes in source

bitmap.UnlockBits(data);
return bitmap;
}

static void Main()
{
var form = new Form();

form.AutoSize = true;
form.Size = new Size(0, 0);
form.Text = "Test";

form.FormClosed += delegate
{
Application.Exit();
};

worker = new BackgroundWorker();

worker.DoWork += delegate
{

while (true)
{
var a = DateTime.Now;
pb.Image = Randimg();
var b = DateTime.Now;

time += (b - a).TotalSeconds;
frames += 1;

if (frames == 30)
{
Console.WriteLine("{0} frames in {1:0.000} seconds. ({2:0} FPS)", frames, time, frames / time);

time = 0;
frames = 0;
}
}
};

worker.RunWorkerAsync();

FlowLayoutPanel flp = new FlowLayoutPanel();

pb = new PictureBox();
pb.Size = size;

flp.AutoSize = true;

form.Show();
Application.Run();
}
}
```

## C++

### Version 1 (windows.h)

```#include <windows.h>
#include <sstream>
#include <tchar.h>
//--------------------------------------------------------------------------------------------------
using namespace std;

//--------------------------------------------------------------------------------------------------
const unsigned int BMP_WID = 320, BMP_HEI = 240, WHITE = 16777215, BLACK = 0;

//--------------------------------------------------------------------------------------------------
class myBitmap
{
public:
myBitmap() : pen( NULL ), brush( NULL ), clr( 0 ), wid( 1 ) {}
~myBitmap()
{
DeleteObject( pen ); DeleteObject( brush );
DeleteDC( hdc ); DeleteObject( bmp );
}

bool create( int w, int h )
{
BITMAPINFO    bi;
ZeroMemory( &bi, sizeof( bi ) );
bi.bmiHeader.biBitCount    = sizeof( DWORD ) * 8;
HDC dc = GetDC( GetConsoleWindow() );
bmp = CreateDIBSection( dc, &bi, DIB_RGB_COLORS, &pBits, NULL, 0 );
if( !bmp ) return false;
hdc = CreateCompatibleDC( dc );
SelectObject( hdc, bmp );
ReleaseDC( GetConsoleWindow(), dc );
width = w; height = h;
return true;
}

void clear( BYTE clr = 0 )
{
memset( pBits, clr, width * height * sizeof( DWORD ) );
}

void setBrushColor( DWORD bClr )
{
if( brush ) DeleteObject( brush );
brush = CreateSolidBrush( bClr );
SelectObject( hdc, brush );
}

void setPenColor( DWORD c ) { clr = c; createPen(); }
void setPenWidth( int w ) { wid = w; createPen(); }

void saveBitmap( string path )
{
BITMAP           bitmap;
DWORD            wb;

GetObject( bmp, sizeof( bitmap ), &bitmap );
DWORD* dwpBits = new DWORD[bitmap.bmWidth * bitmap.bmHeight];
ZeroMemory( dwpBits, bitmap.bmWidth * bitmap.bmHeight * sizeof( DWORD ) );
ZeroMemory( &infoheader, sizeof( BITMAPINFO ) );
GetDIBits( hdc, bmp, 0, height, ( LPVOID )dwpBits, &infoheader, DIB_RGB_COLORS );
HANDLE file = CreateFile( path.c_str(), GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL );
WriteFile( file, dwpBits, bitmap.bmWidth * bitmap.bmHeight * 4, &wb, NULL );
CloseHandle( file );

delete [] dwpBits;
}

void* getBits( void ) const { return pBits; }
HDC getDC() const     { return hdc; }
int getWidth() const  { return width; }
int getHeight() const { return height; }

private:
void createPen()
{
if( pen ) DeleteObject( pen );
pen = CreatePen( PS_SOLID, wid, clr );
SelectObject( hdc, pen );
}

HBITMAP bmp;
HDC     hdc;
HPEN    pen;
HBRUSH  brush;
void*   pBits;
int     width, height, wid;
DWORD   clr;
};
//--------------------------------------------------------------------------------------------------
class bmpNoise
{
public:
bmpNoise()
{
QueryPerformanceFrequency( &_frequency );
_bmp.create( BMP_WID, BMP_HEI );
_frameTime = _fps = 0; _start = getTime(); _frames = 0;
}

void mainLoop()
{
float now = getTime();
if( now - _start > 1.0f ) { _fps = static_cast<float>( _frames ) / ( now - _start ); _start = now; _frames = 0; }
HDC wdc, dc = _bmp.getDC();
unsigned int* bits = reinterpret_cast<unsigned int*>( _bmp.getBits() );

for( int y = 0; y < BMP_HEI; y++ )
{
for( int x = 0; x < BMP_WID; x++ )
{
if( rand() % 10 < 5 ) memset( bits, 255, 3 );
else memset( bits, 0, 3 );
bits++;
}
}
ostringstream o; o << _fps; TextOut( dc, 0, 0, o.str().c_str(), o.str().size() );

wdc = GetDC( _hwnd );
BitBlt( wdc, 0, 0, BMP_WID, BMP_HEI, dc, 0, 0, SRCCOPY );
ReleaseDC( _hwnd, wdc );
_frames++; _frameTime = getTime() - now;
if( _frameTime > 1.0f ) _frameTime = 1.0f;
}

void setHWND( HWND hwnd ) { _hwnd = hwnd; }

private:
float getTime()
{
LARGE_INTEGER liTime; QueryPerformanceCounter( &liTime );
}
myBitmap      _bmp;
HWND          _hwnd;
float         _start, _fps, _frameTime;
unsigned int  _frames;
LARGE_INTEGER _frequency;
};
//--------------------------------------------------------------------------------------------------
class wnd
{
public:
wnd() { _inst = this; }
int wnd::Run( HINSTANCE hInst )
{
_hInst = hInst; _hwnd = InitAll();
_noise.setHWND( _hwnd );
ShowWindow( _hwnd, SW_SHOW );
UpdateWindow( _hwnd );

MSG msg;
ZeroMemory( &msg, sizeof( msg ) );
while( msg.message != WM_QUIT )
{
if( PeekMessage( &msg, NULL, 0, 0, PM_REMOVE ) != 0 )
{
TranslateMessage( &msg );
DispatchMessage( &msg );
}
else
{
_noise.mainLoop();
}
}
return UnregisterClass( "_MY_NOISE_", _hInst );
}
private:
static int WINAPI wnd::WndProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam )
{
switch( msg )
{
case WM_DESTROY: PostQuitMessage( 0 ); break;
default:
return DefWindowProc( hWnd, msg, wParam, lParam );
}
return 0;
}

HWND InitAll()
{
WNDCLASSEX wcex;
ZeroMemory( &wcex, sizeof( wcex ) );
wcex.cbSize           = sizeof( WNDCLASSEX );
wcex.style           = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc   = ( WNDPROC )WndProc;
wcex.hInstance     = _hInst;
wcex.hCursor       = LoadCursor( NULL, IDC_ARROW );
wcex.hbrBackground = ( HBRUSH )( COLOR_WINDOW + 1 );
wcex.lpszClassName = "_MY_NOISE_";

RegisterClassEx( &wcex );

RECT rc = { 0, 0, BMP_WID, BMP_HEI };
int w = rc.right - rc.left, h = rc.bottom - rc.top;
return CreateWindow( "_MY_NOISE_", ".: Noise image -- PJorente :.", WS_SYSMENU, CW_USEDEFAULT, 0, w, h, NULL, NULL, _hInst, NULL );
}

static wnd* _inst;
HINSTANCE   _hInst;
HWND        _hwnd;
bmpNoise    _noise;
};
wnd* wnd::_inst = 0;
//--------------------------------------------------------------------------------------------------
int APIENTRY _tWinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow )
{
srand( GetTickCount() ); wnd myWnd;
return myWnd.Run( hInstance );
}
//--------------------------------------------------------------------------------------------------
```

### Version 2 (SDL2)

Library: SDL2
```// Standard C++ stuff
#include <iostream>
#include <string>
#include <random>

// SDL2 stuff
#include "SDL2/SDL.h"

// Other crazy stuffs
#define SCREEN_WIDTH  320
#define SCREEN_HEIGHT 240
#define COLOUR_BLACK  0,    0,    0,    0xff
#define COLOUR_WHITE  0xff, 0xff, 0xff, 0xff

// Compile: g++ -std=c++20 -Wall -Wextra -pedantic ImageNoise.cpp -o ImageNoise -lSDL2

template <class RandomGenerator>
void BlitNoise(SDL_Renderer *r, int width, int height, auto &dist, RandomGenerator &generator) {
for (int y = 0; y < height; ++y) {
for (int x = 0; x < width; ++x) {
// Use the random number generator in C++ Standard Library to determine draw colour
if (dist(generator) == 0)
// Set colour to black
SDL_SetRenderDrawColor(r, COLOUR_BLACK);
else if (dist(generator) == 1)
// Set colour to white
SDL_SetRenderDrawColor(r, COLOUR_WHITE);
// Go through every scanline, and put pixels
SDL_RenderDrawPoint(r, x, y);
}
}
}

void UpdateFPS(unsigned &frame_count, unsigned &timer, SDL_Window *window) {
static Uint64 LastTime = 0;
std::string NewWindowTitle;
Uint64 Time = SDL_GetTicks(),
Delta = Time - LastTime;
timer += Delta;
if (timer > 1000) {
unsigned ElapsedTime = timer / 1000;
NewWindowTitle = "Image noise - " + std::to_string((int)((float)frame_count/(float)ElapsedTime)) + " FPS"; // Dirty string trick
SDL_SetWindowTitle(window, const_cast<char*>(NewWindowTitle.c_str()));
timer = 0;
frame_count = 0;
NewWindowTitle.clear();
}
LastTime = Time;
}

int main() {
std::random_device Device; // Random number device
std::mt19937_64 Generator(Device()); // Random number generator
std::uniform_int_distribution ColourState(0, 1); // Colour state
unsigned Frames = 0,
Timer = 0;

SDL_Window *Window = NULL; // Define window
SDL_Renderer *Renderer = NULL; // Define renderer

// Init everything just for sure
SDL_Init(SDL_INIT_EVERYTHING);

// Set window size to 320x240, always shown
Window = SDL_CreateWindow("Image noise - ?? FPS", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
Renderer = SDL_CreateRenderer(Window, -1, SDL_RENDERER_ACCELERATED);

// Set background colour to white
SDL_SetRenderDrawColor(Renderer, COLOUR_WHITE);
SDL_RenderClear(Renderer);

// Create an event handler and a "quit" flag
SDL_Event e;
bool KillWindow = false;

// The window runs until the "quit" flag is set to true
while (!KillWindow) {
while (SDL_PollEvent(&e) != 0) {
// Go through the events in the queue
switch (e.type) {
// Event: user hits a key
case SDL_QUIT: case SDL_KEYDOWN:
// Destroy window
KillWindow = true;
break;
}
}
// Render the noise
BlitNoise(Renderer, SCREEN_WIDTH, SCREEN_HEIGHT, ColourState, Generator);
SDL_RenderPresent(Renderer);
// Increment the "Frames" variable.
// Then show the FPS count in the window title.
++Frames;
UpdateFPS(Frames, Timer, Window);
}

// Destroy renderer and window
SDL_DestroyRenderer(Renderer);
SDL_DestroyWindow(Window);
SDL_Quit();

return 0;
}
```
Output:

## Common Lisp

noise_sdl.lisp:

```;; (require :lispbuilder-sdl)

(defun draw-noise (surface)
"draws noise on the surface. Returns the surface"
(let ((width (sdl:width surface))
(height (sdl:height surface))
(i-white (sdl:map-color sdl:*white* surface))
(i-black (sdl:map-color sdl:*black* surface)))
(sdl-base::with-pixel (s (sdl:fp surface))
(dotimes (h height)
(dotimes (w width)
(sdl-base::write-pixel s w h (if (zerop (random 2))
i-white i-black ))))))
surface)

(defun draw-fps (surface)
"draws fps text-info on surface. Returns surface"
(sdl:with-surface (s surface)
(sdl:draw-string-solid-* (format nil "FPS: ~,3f" (sdl:average-fps))
20 20 :surface s :color sdl:*magenta*)))

(defun main ()
"main function, initializes the library and creates de display window"
(setf *random-state* (make-random-state))
(sdl:with-init (SDL:SDL-INIT-VIDEO SDL:SDL-INIT-TIMER)
(let ((main-window (sdl:window 320 240
:title-caption "noise_sdl.lisp"
:bpp 8
:flags (logior SDL:SDL-DOUBLEBUF SDL:SDL-HW-SURFACE)
:fps (make-instance 'sdl:fps-unlocked))))
(sdl:initialise-default-font)
(sdl:with-events ()
(:idle ()
(sdl:update-display (draw-fps (draw-noise main-window))))
(:video-expose-event ()
(sdl:update-display))
(:quit-event () T)))))

(main)
```

## D

Translation of: C
```import std.stdio, std.random, sdl.SDL;

void main() {
SDL_Init(SDL_INIT_TIMER | SDL_INIT_VIDEO);
auto surface = SDL_SetVideoMode(320,240,8, SDL_DOUBLEBUF|SDL_HWSURFACE);

while (true) {
SDL_LockSurface(surface);
foreach (i; 0 .. surface.w * surface.h)
(cast(ubyte*)surface.pixels)[i] = (uniform(0, 2) ? 255 : 0);
SDL_UnlockSurface(surface);
SDL_Flip(surface);

uint time = SDL_GetTicks();
totalTime += time - lastTime;
if (totalTime > 1000) {
writeln("FPS: ", frameNumber / (totalTime / 1000.0));
}
lastTime = time;
}
}
```

This D version shows about 155 FPS, while on the same PC the C version shows about 180 FPS.

Generating random bits with the C core.stdc.stdlib.rand the performance becomes about the same of the C version.

## Delphi

Library: Vcl.Forms
```unit Main;

interface

uses
Winapi.Windows, System.SysUtils, Vcl.Forms, Vcl.Graphics, Vcl.Controls,
System.Classes, Vcl.ExtCtrls;

type
TfmNoise = class(TForm)
tmr1sec: TTimer;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure FormPaint(Sender: TObject);
procedure tmr1secTimer(Sender: TObject);
end;

var
fmNoise: TfmNoise;
Surface: TBitmap;
FrameCount: Cardinal = 0;

implementation

{\$R *.dfm}

procedure TfmNoise.FormCreate(Sender: TObject);
begin
Surface := TBitmap.Create;
Surface.SetSize(320, 240);
Surface.PixelFormat := pf1bit;
Randomize;
end;

procedure TfmNoise.FormDestroy(Sender: TObject);
begin
Surface.Free;
end;

type
PDWordArray = ^TDWordArray;

TDWordArray = array[0..16383] of DWord;

procedure TfmNoise.FormPaint(Sender: TObject);
var
x, y: Integer;
line: PWordArray;
begin
with Surface do
for y := 0 to Height - 1 do
begin
line := Surface.ScanLine[y];
for x := 0 to (Width div 16) - 1 do
line[x] := Random(\$FFFF);
// Fill 16 pixels at same time
end;

Canvas.Draw(0, 0, Surface);
Inc(FrameCount);
Application.ProcessMessages;
Invalidate;
end;

procedure TfmNoise.tmr1secTimer(Sender: TObject);
begin
Caption := 'FPS: ' + FrameCount.ToString;
FrameCount := 0;
end;

end.
```

Resources form:

```object fmNoise: TfmNoise
Left = 0
Top = 0
BorderStyle = bsSingle
Caption = 'fmNoise'
ClientHeight = 240
ClientWidth = 320
OnCreate = FormCreate
OnDestroy = FormDestroy
OnPaint = FormPaint
object tmr1sec: TTimer
Interval = 2000
OnTimer = tmr1secTimer
end
end
```
Output:
```   1400 to 1600 FPS
```

## EasyLang

```proc pset x y c . .
color c
move x / 3.2 y / 3.2
rect 0.3 0.3
.
on animate
fr += 1
if systime - t0 >= 1
move 10 78
color -2
rect 80 20
color -1
move 10 80
text fr / (systime - t0) & " fps"
t0 = systime
fr = 0
.
col[] = [ 000 999 ]
for x = 0 to 319
for y = 0 to 199
pset x y col[randint 2]
.
.
.```

## Euler Math Toolbox

Currently, Euler Math Toolbox does not have optimized routines to plot matrices with color information. The frames per second are consequently not really good.

```>function noiseimg () ...
\$aspect(320,240); clg;
\$count=0; now=time;
\$repeat
\$  plotrgb(intrandom(240,420,2)-1,[0,0,1024,1024]);
\$  wait(0);
\$  count=count+1;
\$  until testkey();
\$end;
\$return count/(time-now);
\$endfunction
>noiseimg
2.73544353263```

## F#

This implementation includes two methods to update the pixels values. One uses unsafe methods and can do 350 fps on my machine, the second uses safe code to marshal the new values onto the bitmap data and can do 240 fps on the same machine.

```open System.Windows.Forms
open System.Drawing
open System.Drawing.Imaging
open System.Runtime.InteropServices
open System.Diagnostics
open Microsoft.FSharp.NativeInterop
#nowarn "9"

let rnd = System.Random()

// Draw pixels using unsafe native pointer accessor.
// This updates the bitmap as fast as possible.
let drawbits_fast (size:int) (bits:BitmapData) =
let mutable (p:nativeptr<byte>) = NativePtr.ofNativeInt(bits.Scan0)
for n = 0 to size-1 do
let c = rnd.Next(2) * 255
NativePtr.set p 2 (byte c)
NativePtr.set p 1 (byte c)
NativePtr.set p 0 (byte c)
NativePtr.set p 3 (byte 255)

// A reasonably efficient updater using marshalling to copy an array of generated
// integers onto the managed bitmap pixel data (see the C# example as well).
let drawbits_safe (size:int) (bits:BitmapData) =
let data = Array.init size (fun n ->
let c = rnd.Next(2) * 255
0xff000000 ||| (c <<< 16) ||| (c <<< 8) ||| c)
Marshal.Copy(data, 0, bits.Scan0, size) |> ignore

// Create a new bitmap and update using the specified function
let make_image (width:int) (height:int) f =
let size = width * height
let bmp = new Bitmap(width, height)
let bits = bmp.LockBits(Rectangle(0,0,width,height), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb)
f size bits
bmp.UnlockBits(bits)
bmp

// Draw 30 frames and record the time and display the frames per second
// This function is run asynchronously to avoid blocking the main GUI thread.
let drawImage (box:PictureBox) (label:Label) f = async {
while true do
let timer = new Stopwatch()
timer.Start()
for frames = 0 to 29 do
let bmp = make_image 320 240 f
box.Image <- bmp
timer.Stop()
let fps = 30000. / timer.Elapsed.TotalMilliseconds
label.Text <- sprintf "%.1f fps" fps }

[<EntryPoint>]
let main args =
let form = new Form(AutoSize=true,
Size=new Size(0,0),
Text="image noise demo")
let panel = new FlowLayoutPanel(AutoSize=true,FlowDirection=FlowDirection.TopDown)
let box = new PictureBox(AutoSize=true)
let label = new Label(AutoSize=true, Text="Ready")
Application.Exit())
if args.Length > 0 && args.[0] = "-safe" then
drawImage box label drawbits_safe |> Async.Start
else
drawImage box label drawbits_fast |> Async.Start
form.Show()
Application.Run()
0
```

## Factor

~150 FPS

```USING: accessors calendar images images.viewer kernel math
math.parser models models.arrow random sequences threads timers
IN: rosetta-code.image-noise

: bits>pixels ( bits -- bits' pixels )
[ -1 shift ] [ 1 bitand ] bi 255 * ; inline

: ?generate-more-bits ( a bits -- a bits' )
over 32 mod zero? [ drop random-32 ] when ; inline

: <random-images-bytes> ( dim -- bytes )
[ 0 0 ] dip product  [
?generate-more-bits
[ 1 + ] [ bits>pixels ] bi*
] B{ } replicate-as 2nip ;

: <random-bw-image> ( -- image )
<image>
{ 320 240 } [ >>dim ] [ <random-images-bytes> >>bitmap ] bi
L >>component-order
ubyte-components >>component-type ;

TUPLE: bw-noise-gadget < image-control timers cnt old-cnt fps-model ;

: animate-image ( control -- )
[ 1 + ] change-cnt
model>> <random-bw-image> swap set-model ;

: update-cnt ( gadget -- )
[ cnt>> ] [ old-cnt<< ] bi ;

: fps ( gadget -- fps )
[ cnt>> ] [ old-cnt>> ] bi - ;

: fps-monitor ( gadget -- )
[ fps ] [ update-cnt ] [ fps-model>> set-model ] tri ;

: start-animation ( gadget -- )
[ [ animate-image ] curry 1 nanoseconds every ] [ timers>> push ] bi ;

: start-fps ( gadget -- )
[ [ fps-monitor ] curry 1 seconds every ] [ timers>> push ] bi ;

: setup-timers ( gadget -- )
[ start-animation ] [ start-fps ] bi ;

: stop-animation ( gadget -- )
timers>> [ [ stop-timer ] each ] [ delete-all ] bi ;

M: bw-noise-gadget graft* [ call-next-method ] [ setup-timers ] bi ;

M: bw-noise-gadget ungraft* [ stop-animation ] [ call-next-method ] bi ;

0 >>cnt 0 >>old-cnt 0 <model> >>fps-model V{ } clone >>timers ;

[ number>string ] <arrow> <label-control>
"FPS: " <label>

MAIN-WINDOW: open-noise-window
{ { title "Black and White noise" } }
```

## Forth

Works with: gforth version 0.7.3
Library: SDL2
```\ Bindings to SDL2 functions
\c #include <SDL2/SDL.h>
c-function sdl-init	            SDL_Init                n -- n
c-function sdl-quit	            SDL_Quit                -- void
c-function sdl-createwindow     SDL_CreateWindow        a n n n n n -- a
c-function sdl-createrenderer   SDL_CreateRenderer      a n n -- a
c-function sdl-setdrawcolor     SDL_SetRenderDrawColor  a n n n n -- n
c-function sdl-drawpoint        SDL_RenderDrawPoint     a n n -- n
c-function sdl-renderpresent    SDL_RenderPresent       a -- void
c-function sdl-delay            SDL_Delay               n -- void
c-function sdl-ticks            SDL_GetTicks            -- n

require random.fs

0 value window
0 value renderer
240 constant height
320 constant width

: black   0   0   0 255 ;
: white 255 255 255 255 ;
: black-or-white 2 random if black else white then ;

: init-image ( -- )
\$20 sdl-init drop
s\" Rosetta Task : Image Noise\x0" drop 0 0 width height \$0 sdl-createwindow to window
window -1 \$2 sdl-createrenderer to renderer
page
;

: image-noise-generate
height 0 do
width 0 do
renderer black-or-white sdl-setdrawcolor drop
renderer i j sdl-drawpoint drop
loop
loop
;

: .FPS swap - 1000 swap / 0 0 at-xy . ." FPS" ;

: image-noise
init-image
100 0 do
sdl-ticks
image-noise-generate     renderer sdl-renderpresent
sdl-ticks .FPS
loop
sdl-quit
;

image-noise
```

## FreeBASIC

```' version 13-07-2018
' compile with: fbc -s console
'           or: fbc -s gui

' hit any to key to stop program

Randomize Timer
Screen 13

If ScreenPtr = 0 Then
Print "Error setting video mode!"
End
End If

Palette 0, 0                  ' black
Palette 1, RGB(255, 255, 255) ' white

Dim As UInteger c, x, y, Col
Dim As Double fps, t = Timer

' empty keyboard buffer
While InKey <> "" : Wend

While InKey = ""

For x = 0 To 319
For y = 0 To 199
' color is as integer, a float gets rounded off by FreeBASIC
PSet(x, y), Rnd
Next
Next
c += 1
fps = c / (Timer - t)
WindowTitle "fps = " + Str(fps)

Wend```

## FutureBasic

FB has native image noise filters.

```_window = 1
begin enum output 1
_noiseView
_fpsLabel
end enum

void local fn BuildWindow

CGRect  r = fn CGRectMake( 0, 0, 340, 300 )

r = fn CGRectMake( 10, 50, 320, 240 )
imageview _noiseView, YES, , r, NSImageScaleAxesIndependently, NSImageAlignCenter, NSImageFrameNone, _window

r = fn CGRectMake( 20, 10, 280, 24 )
textlabel _fpsLabel, @"Estimated FPS: 60", r, _window
ControlSetAlignment( _fpsLabel, NSTextAlignmentCenter )
end fn

local fn CIImageToImageRef( ciImage as CIImageRef ) as ImageRef
CIImageRepRef rep = fn CIImageRepWithCIImage( ciImage )
CGSize       size = fn ImageRepSize( rep )
ImageRef    image = fn ImageWithSize( size )
end fn = image

local fn NoiseCIImage as CIImageRef
CIFilterRef filter = fn CIFilterWithName( @"CIPhotoEffectNoir" )
ObjectSetValueForKey( filter, fn ObjectValueForKey( fn CIFilterWithName(@"CIRandomGenerator"), @"outputImage" ), @"inputImage" )
CIFilterSetDefaults( filter )
CIImageRef outputCIImage = fn CIImageByCroppingToRect( fn CIFilterOutputImage( filter ), fn CGRectMake( rnd(1000), rnd(1000), 500, 500 ) )
end fn = outputCIImage

local fn BuildNoiseView
block NSInteger renderedFrames

renderedFrames = 0
timerbegin, 1.0/60, YES
CIImageRef noiseCIImage = fn NoiseCIImage
ImageRef   noiseImage   = fn CIImageToImageRef( noiseCIImage )
ImageViewSetImage( _noiseView, noiseImage )
renderedFrames++
if( renderedFrames == 60 )
ControlSetStringValue( _fpsLabel, fn StringWithFormat( @"Estimated FPS: %ld", renderedFrames ) )
renderedFrames = 0
end if
timerend
end fn

void local fn DoDialog( ev as long, tag as long, wnd as long )
select ( ev )
case _windowWillClose : end
end select
end fn

randomize

on dialog fn DoDialog

fn BuildWindow
fn BuildNoiseView

HandleEvents```
Output:

## Go

```package main

import (
"fmt"
"image"
"image/color"
"image/draw"
"log"
"os"
"time"
)

var randcol = genrandcol()

func genrandcol() <-chan color.Color {
c := make(chan color.Color)

go func() {
for {
select {
case c <- image.Black:
case c <- image.White:
}
}
}()

return c
}

func gennoise(screen draw.Image) {
for y := 0; y < 240; y++ {
for x := 0; x < 320; x++ {
screen.Set(x, y, <-randcol)
}
}
}

func fps() chan<- bool {
up := make(chan bool)

go func() {
var frames int64
var lasttime time.Time
var totaltime time.Duration

for {
<-up
frames++
now := time.Now()
totaltime += now.Sub(lasttime)
if totaltime > time.Second {
fmt.Printf("FPS: %v\n", float64(frames)/totaltime.Seconds())
frames = 0
totaltime = 0
}
lasttime = now
}
}()

return up
}

func main() {
win, err := x11.NewWindow()
if err != nil {
fmt.Println(err)
os.Exit(1)
}
defer win.Close()

go func() {
upfps := fps()
screen := win.Screen()

for {
gennoise(screen)

win.FlushImage()

upfps <- true
}
}()

for _ = range win.EventChan() {
}
}
```

### Optimized example

A second example that is somewhat more optimized but maybe more complicated. (~3000fps on a Thinkpad x220 laptop)

```package main

/* Note, the x-go-binding/ui/x11 lib is under development and has as a temp solution
set the x window to a static height and with, you have to manualy set these
to 240 x 320 in code.google.com/p/x-go-binding/ui/x11/conn.go */

import "fmt"
import "image"
import "image/draw"
import "log"
import "math/rand"
import "runtime"
import "time"

var bw[65536][64]byte
var frameCount = make(chan uint)

func main() {
tc := runtime.NumCPU()
runtime.GOMAXPROCS(tc)

// Initiate a new x11 screen to print images onto
win, err := x11.NewWindow()
if err != nil {
log.Fatalln(err)
}
defer win.Close()
screen := win.Screen()
_, ok := screen.(*image.RGBA)
if !ok {
log.Fatalln("screen isn't an RGBA image.")
}

//Create lookup table for every combination of 16 black/white pixels
var i, j uint
for i = 0; i< 65536; i++ {
for j = 0; j < 16; j++ {
if i & (1 << j) > 0 {
bw[i][j*4 + 0] = 0xFF
bw[i][j*4 + 1] = 0xFF
bw[i][j*4 + 2] = 0xFF
}
}
}
// Start fps counter in a new goroutin
go fps()
// Start goroutines
for i := 0; i < tc; i++ {
go createNoise(win, screen)
}
createNoise(win, screen)
}

func createNoise(win ui.Window, screen draw.Image) {
var rnd, rnd2 uint64
var rnd16a, rnd16b, rnd16c, rnd16d uint16
var img [240 * 320 * 4]byte
// Populate the image with pixel data
for {
for i := 0; i < len(img); i += 256 {
rnd = uint64(rand.Int63())
if (i % 63) == 0 {
rnd2 = uint64(rand.Int63())
}
rnd |= rnd2 & 1 << 63 // we have to set the 64'th bit from the rand.Int63() manualy
rnd16a = uint16( rnd        & 0x000000000000FFFF)
rnd16b = uint16((rnd >> 16) & 0x000000000000FFFF)
rnd16c = uint16((rnd >> 32) & 0x000000000000FFFF)
rnd16d = uint16((rnd >> 48) & 0x000000000000FFFF)
copy(img[i    :i+ 64], bw[rnd16a][:])
copy(img[i+ 64:i+128], bw[rnd16b][:])
copy(img[i+128:i+192], bw[rnd16c][:])
copy(img[i+192:i+256], bw[rnd16d][:])
rnd2 = rnd2 >> 1 // rotate to next random bit
}
// Copy pixel data to the screen
copy(screen.(*image.RGBA).Pix, img[:])
frameCount <- 1
win.FlushImage()
}
}

func fps() {
last := time.Now()
var fps uint
for {
// wait for a frameCount update
<-frameCount
fps++
if time.Since(last) >= time.Second {
fmt.Println("fps:", fps)
fps = 0
last = time.Now()
}
}
}
```

This uses the GLFW-b bindings for GLFW 3 support:

`cabal install glfw-b`
```import qualified Graphics.Rendering.OpenGL as GL
import qualified Graphics.UI.GLFW as GLFW
import qualified Foreign as F
import qualified System.Random as R

height = 240
width = 320
numbytes = height * width
imagesize = GL.Size (fromIntegral width) (fromIntegral height)

main :: IO ()
main = do
isInit <- GLFW.init
if isInit
then do
m <- GLFW.createWindow width height "" Nothing Nothing
case m of
Just win -> do
GLFW.makeContextCurrent m
GLFW.swapInterval 1
GLFW.setKeyCallback win \$ Just keyCallback
glLoop win
GLFW.destroyWindow win
Nothing  -> return ()
GLFW.terminate
else return ()

glLoop :: GLFW.Window -> IO ()
glLoop win = do
foreignPixels <- F.mallocForeignPtrArray numbytes
F.withForeignPtr foreignPixels
(\pixels -> do
let pixelData = GL.PixelData GL.Luminance GL.UnsignedByte pixels
loop pixelData pixels 0)
where
loop pixelData pixels frames = do
close <- GLFW.windowShouldClose win
if close
then return ()
else do
randomizePixels pixels
GL.drawPixels imagesize pixelData
GLFW.swapBuffers win
GLFW.pollEvents
time <- GLFW.getTime
let fps =
case time of
Just t  -> show \$ (fromIntegral frames) / t
Nothing -> "???"
GLFW.setWindowTitle win \$ "FPS: " ++ fps
loop pixelData pixels \$ frames + 1

randomizePixels :: F.Ptr GL.GLubyte -> IO ()
randomizePixels ptr = iter 0 numbytes
where
iter index range
| index == range = return ()
| otherwise = do
v <- R.randomRIO (0, 1)
F.pokeElemOff ptr index \$ v * 255
iter (index + 1) range

keyCallback :: GLFW.Window -> GLFW.Key -> Int -> GLFW.KeyState ->
GLFW.ModifierKeys -> IO ()
keyCallback win key _ action _ =
case key of
GLFW.Key'Q -> GLFW.setWindowShouldClose win True
_          -> return ()
```

## Icon and Unicon

Icon/Unicon provide a portable graphics interface that runs on multiple platforms. The frame rates will be lower than many of the other languages. There are several possible approaches to painting this random noise.

• Using DrawPoint(c,r) for each pixel base on essentially a coin flip (speed ~= 1x)
• Using DrawPoint!L on a list L := [c1,r1,c2,r2,...] of foreground pixels to be painted based on a coin flip (speed ~= 2x)
• Using DrawImage to draw a randomly constructed bi-level images(see pg 157 of the graphics book, speed ~= 10x)
```link printf

procedure main()
&window := open("B&W noise 320x240","g","size=320,240","bg=white","fg=black") |
stop("Open window failed ")
runtime := 10 # seconds to run
sec := &now
frames := 0
until (&now - sec) >= runtime do {
s := "320,#"
every 1 to 240 & 1 to 320/4 do s ||:= ?"0123456789ABCDEF"
DrawImage(0,0,s)
frames +:= 1
}
sec := &now - sec
printf("frames=%d, elapsed time=%r, fps=%r\n",frames,sec, frames/real(sec))
Event()   # wait for any window event
close(&window)
end
```

## J

```coclass'example'
(coinsert[require)'jzopengl'

P=: 0 : 0
pc p nosize;
xywh 0 0 160 120;cc c isigraph opengl;
pas 0 0;pcenter;
rem form end;
pshow;
timer 1;
)

timestamp=: (6!:8'') %~ 6!:9

create=:3 :0
ogl=:''conew'jzopengl'
frames=:0
start=: timestamp''
sys_timer_base_=: ''1 :('p_c_paint_',(;coname''),'_')
wd P
)

p_run=: 3 : 0
''conew'example'
)

destroy=:3 :0
end=:timestamp''
smoutput 'frames per second: ',":frames%end-start
wd 'timer 0'
destroy__ogl''
wd'pclose'
codestroy''
)

p_close=: destroy

p_c_paint=: 3 : 0
rc__ogl''
glClear GL_COLOR_BUFFER_BIT
glBegin GL_POINTS
glVertex _1+2*53050 2?@\$ 0
glEnd''
show__ogl''
frames=:frames+1
)

p_run''
```

The script auto-starts when run (that last line `p_run''` is responsible for the auto-start.

Average FPS are displayed when the window is closed.

With this revision, on my laptop, I typically get in the range of 58..59 FPS, with a cpu load from J of about 3% (sometimes as much as 5%, sometimes as low as 0.1%). I am probably limited by v-sync, and (hypothetically speaking) if I tuned my opengl drivers I perhaps could get significantly faster fps. However, since my screen only refreshes approximately 60 times per second, anything over that would be meaningless.

About some of the constants: 160 120 corresponds to a 320 by 240 rendering area (this J version 6 mechanism will be obsolete soon, but I think we should wait for the new code bases stabilize before replacing this code), and the rendering area is not resizable. 53050 was picked because on average half of the pixels will be dark and half of them will be light: We have a black background and 53050 random pixel coordinates (out of 75800 total pixels) being set to being light -- because so many of them will randomly overlap we have on average approximately 50% of each. It would be more efficient to use a pixel shader, pushing the randomizing process into the graphics hardware. But, with this small of a display, efficiency is not really an issue with this approach.

## Java

This could be done more concisely, but the version below features the following enhancements:

- Resizable window

- Real-time blurring of noise behind the FPS display

- Cycling through FPS display modes using mouse clicks

- Very fast: 1000+ FPS on a 2.8 GHz Core Duo (with 64-bit JRE). This is capped because the maximum resolution of the timers available is 1 ms

```import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.util.Arrays;
import java.util.Random;
import javax.swing.*;

public class ImageNoise {
int framecount = 0;
int fps = 0;
BufferedImage image;
Kernel kernel;
ConvolveOp cop;
JFrame frame = new JFrame("Java Image Noise");

JPanel panel = new JPanel() {
private int show_fps = 0; // 0 = blur + FPS; 1 = FPS only; 2 = neither
@Override
public void mouseClicked(MouseEvent e) {
show_fps = (show_fps + 1) % 3;
}
};

@Override
public Dimension getPreferredSize() {
return new Dimension(320, 240);
}

@Override
@SuppressWarnings("fallthrough")
public void paintComponent(Graphics g1) {
Graphics2D g = (Graphics2D) g1;
drawNoise();
g.drawImage(image, 0, 0, null);

switch (show_fps) {
case 0:
int xblur = getWidth() - 130, yblur = getHeight() - 32;
BufferedImage bc = image.getSubimage(xblur, yblur, 115, 32);
BufferedImage bs = new BufferedImage(bc.getWidth(), bc.getHeight(),
BufferedImage.TYPE_BYTE_GRAY);
cop.filter(bc, bs);
g.drawImage(bs, xblur, yblur , null);
case 1:
// add FPS text; case fallthough is deliberate
g.setColor(Color.RED);
g.setFont(new Font("Monospaced", Font.BOLD, 20));
g.drawString("FPS: " + fps, getWidth() - 120, getHeight() - 10);
}
framecount++;
}
};

// Timer to trigger update display, with 1 ms delay
Timer repainter = new Timer(1, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
panel.repaint();
}
});

// Timer to check FPS, once per second
Timer framerateChecker = new Timer(1000, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
fps = framecount;
framecount = 0;
}
});

public ImageNoise() {
// Intitalize kernel describing blur, and convolve operation based on this
float[] vals = new float[121];
Arrays.fill(vals, 1/121f);
kernel = new Kernel(11, 11, vals);
cop = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);

// Initialize frame and timers
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
repainter.start();
framerateChecker.start();
}

void drawNoise() {
int w = panel.getWidth(), h = panel.getHeight();

// Check if our image is null or window has been resized, requiring new image
if (null == image || image.getWidth() != w || image.getHeight() != h) {
image = new BufferedImage(w, h, BufferedImage.TYPE_BYTE_GRAY);
}
Random rand = new Random();
int[] data = new int[w * h];
// Each int has 32 bits so we can use each bit for a different pixel - much faster
for (int x = 0; x < w * h / 32; x++) {
int r = rand.nextInt();
for (int i = 0; i < 32; i++) {
data[x * 32 + i] = (r & 1) * Integer.MAX_VALUE;
r >>>= 1;
}
}
// Copy raw data to the image's raster
image.getRaster().setPixels(0, 0, w, h, data);
}

public static void main(String[] args) {
// Invoke GUI on the Event Dispatching Thread
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
ImageNoise i = new ImageNoise();
}
});
}
}
```

## JavaScript

```<body>
<canvas id='c'></canvas>

<script>
var canvas = document.getElementById('c');
var ctx = canvas.getContext('2d');

var w = canvas.width = 320;
var h = canvas.height = 240;
var t1 = new Date().getTime();
var frame_count = 0;
ctx.font = 'normal 400 24px/2 Unknown Font, sans-serif';
var img = ctx.createImageData(w, h);

var index_init = 0;
for (var x = 0; x < w; x++) {
for (var y = 0; y < h; y++) {
img.data[index_init + 3] = 255; // alpha
index_init += 4;
}
}

function animate() {
var index = 0;
for (var x = 0; x < w; x++) {
for (var y = 0; y < h; y++) {
var value = (Math.random() > 0.5) ? 255 : 0;
img.data[index    ] = value;
img.data[index + 1] = value;
img.data[index + 2] = value;
// alpha channel is constant
index += 4;
}
}

ctx.putImageData(img, 0, 0);

frame_count++;
if (frame_count % 50 == 0) {
var fps = frame_count / (new Date().getTime() - t1) * 1000;
window.status = fps.toFixed(2) + " fps";
}

setTimeout(animate, 0);
}

animate();
</script>
</body>
```

About 59 frames/second on Firefox 4.

## Julia

With Gtk, gets about 80 frames per second on a older, dual core 3 Ghz processor.

```using Gtk, GtkUtilities

function randbw(ctx, w, h)
pic = zeros(Int64, w, h)
for i in 1:length(pic)
pic[i] = rand([1, 0])
end
copy!(ctx, pic)
end

const can = @GtkCanvas()
const win = GtkWindow(can, "Image Noise", 320, 240)

@guarded draw(can) do widget
ctx = getgc(can)
h = height(can)
w = width(can)
randbw(ctx, w, h)
end

show(can)
const cond = Condition()
endit(w) = notify(cond)
signal_connect(endit, win, :destroy)

while true
frames = 0
t = time()
for _ in 1:100
draw(can)
show(can)
sleep(0.0001)
frames += 1
end
fps = round(frames / (time() - t), digits=1)
set_gtk_property!(win, :title, "Image Noise: \$fps fps")
end

wait(cond)
```

## Kotlin

Translation of: Java
```// version 1.2.10

import java.awt.*
import java.awt.event.*
import java.awt.image.*
import java.util.Random
import javax.swing.*

class ImageNoise {
var framecount = 0
var fps = 0
lateinit var image: BufferedImage
val kernel: Kernel
lateinit var cop: ConvolveOp
val frame = JFrame("Java Image Noise")

val panel = object : JPanel() {
private var showFps = 0  // 0 = blur + FPS; 1 = FPS only; 2 = neither
private val ma = object : MouseAdapter() {
override fun mouseClicked(e: MouseEvent) {
showFps = (showFps + 1) % 3
}
}

init {
preferredSize = Dimension(320, 240)
}

override fun paintComponent(g1: Graphics) {
val g = g1 as Graphics2D
drawNoise()
g.drawImage(image, 0, 0, null)
if (showFps == 0) {
val xblur = width - 130
val yblur = height - 32
val bc = image.getSubimage(xblur, yblur, 115, 32)
val bs = BufferedImage(
bc.width, bc.height, BufferedImage.TYPE_BYTE_GRAY
)
cop.filter(bc, bs)
g.drawImage(bs, xblur, yblur, null)
}
if (showFps <= 1) {
g.color = Color.RED
g.font = Font("Monospaced", Font.BOLD, 20)
g.drawString("FPS: \$fps", width - 120, height - 10)
}
framecount++
}
}

// Timer to trigger update display, with 1 ms delay
val repainter = Timer(1, object: ActionListener {
override fun actionPerformed(e: ActionEvent) = panel.repaint()
})

// Timer to check FPS, once per second
val framerateChecker = Timer(1000, object : ActionListener {
override fun actionPerformed(e: ActionEvent) {
fps = framecount
framecount = 0
}
})

init {
// Intitalize kernel describing blur, and convolve operation based on this
val vals = FloatArray(121) { 1.0f / 121.0f }
kernel = Kernel(11, 11, vals)
cop = ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null)

// Initialize frame and timers
with (frame) {
defaultCloseOperation = JFrame.EXIT_ON_CLOSE
pack()
isVisible = true
}
repainter.start()
framerateChecker.start()
}

fun drawNoise() {
val w = panel.width
val h = panel.height

// Check if our image is initialized or window has been resized,
// requiring new image
if (!this::image.isInitialized || image.width != w || image.height != h) {
image = BufferedImage(w, h, BufferedImage.TYPE_BYTE_GRAY)
}
val rand = Random()
val data = IntArray(w * h)
// Each int has 32 bits so we can use each bit for a different pixel
// - much faster
for (x in 0 until w * h / 32) {
var r = rand.nextInt()
for (i in 0..31) {
data[x * 32 + i] = (r and 1) * Int.MAX_VALUE
r = r ushr 1
}
}
// Copy raw data to the image's raster
image.raster.setPixels(0, 0, w, h, data)
}
}

fun main(args: Array<String>) {
// Invoke GUI on the Event Dispatching Thread
SwingUtilities.invokeLater(object: Runnable {
override fun run() {
ImageNoise()
}
})
}
```
Output:
```Similar to Java entry
```

## Liberty BASIC

Generates the random bitmap programmatically, then chops it each time in a different way.

```WindowWidth  =411
w            =320
WindowHeight =356
h            =240

open "Noise" for graphics_nsb as #w

#w "trapclose [quit]"
#w "down"

'bitmap header, 320x240 pixels 256 colors
data 66,77,54,48,1,0,0,0,0,0,54,4,0,0,40,0,0,0,64,1
data 0,0,240,0,0,0,1,0,8,0,0,0,0,0,0,44,1,0,0,0
data 0,0,0,0,0,0,0,1,0,0,0,1,0,0

for i = 1 to 54
next

print "Creating BMP grayscale palette"
pal\$=""
for i = 0 to 255
pal\$ = pal\$ _
+ chr\$(i) _
+ chr\$(i) _
+ chr\$(i) _
+ chr\$(0)
next

print "Creating BMP random body"
'create bitmap body
body\$=""
for x =1 To w
l\$=""
for y =1 To h
l\$=l\$+chr\$((rnd(1)>0.5)*255)
next
body\$=body\$+l\$
next

[main]
scan
ts =time\$( "ms")
'randomly "splice" the body: 1111222222-> 2222221111
splice=int(len(body\$)*rnd(1))+1
body\$= mid\$(body\$,splice+1)+left\$(body\$,splice)
'write BMP
open "noise.bmp" for output as #1
#1 body\$;
close #1
#w "cls"
'drawbmp
#w "drawbmp noise 0 0"

tf =time\$( "ms")
dt =tf -ts
if dt = 0 then dt = 1
print "Framerate per second ="; using( "#.###", 1/(dt/1000)), "Ms per frame =";dt
goto [main]

[quit]
close #w
end```

## Maple

• Note, you will need to insert a plot component to get this to work.
```a:=0;
t:=time[real]();
while a< 50 do
a:=a+1;
data := Matrix(`<|>`(`<,>`(Statistics:-Sample(Uniform(0, 1), [1000, 2])), LinearAlgebra:-RandomVector(1000, generator = rand(0 .. 2))));

f := plots:-pointplot(data[NULL .. NULL, 1], data[NULL .. NULL, 2], symbolsize = 20, symbol = solidbox, colorscheme = ["valuesplit", data[NULL .. NULL, 3], [0 = "Black", 1 = "White", 2 = "Grey"]], axes = none);
DocumentTools:-SetProperty('Plot0', 'value', plots:-display(f,plots:-textplot([0.5,0.5,sprintf("FPS: %a", (a/(time[real]()-t)))],color=red)), refresh=true);

end do:```

## Mathematica / Wolfram Language

```time = AbsoluteTime[]; Animate[
Column[{Row[{"FPS: ", Round[n/(AbsoluteTime[] - time)]}],
RandomImage[1, {320, 240}]}], {n, 1, Infinity, 1}]
```

## MAXScript

```try destroydialog testRollout catch ()

fn randomBitmap width height =
(
local newBmp = bitmap width height

for row = 0 to (height-1) do
(
local pixels =  for i in 1 to width collect (white*random 0 1)
setpixels newBmp [0,row] pixels
)

return newBmp
)

rollout testRollout "Test" width:320 height:240
(
bitmap image width:320 height:240 pos:[0,0]
timer updateTimer interval:1 active:true

on updateTimer tick do
(
local startTime = timestamp()
image.bitmap = randomBitmap 320 240
local endTime = timestamp()
local fps = ((endTime-startTime)/1000.0)*60.0

if mod updatetimer.ticks 10 == 0 do (testRollout.title = ("Test (FPS: "+fps as string+")"))

)
)

createdialog testrollout```

## MiniScript

This implementation is for use with Mini Micro.

```clear
tileSetLength = 32
width = 320
height = 240
cellSize = [960/width, 600/height]
colors = [color.black, color.white]

newImg = function
img = Image.create(tileSetLength, 1)
for i in range(0, tileSetLength - 1)
img.setPixel i, 0, colors[rnd * 2]
end for
return img
end function

display(5).mode = displayMode.tile
td = display(5)
td.cellSize = cellSize
td.extent = [width, height]
td.tileSetTileSize = 1
for x in range(0, width - 1)
for y in range(0, height - 1)
td.setCell x, y, rnd * tileSetLength
end for
end for
frames = 0
startTime = time
while true
td.tileSet = newImg
frames += 1
dt = time - startTime
if dt >= 1 then
text.row = 25; print "FPS: " + round(frames / dt, 2)
frames = 0
startTime = time
end if
end while
```

## Nim

### Using OpenGL

Translation of: C
Library: OpenGL

On a small laptop running Manjaro and without a dedicated graphic card, we get 550-600 FPS.

```import times

import opengl
import opengl/glut

const
W = 320
H = 240
SLen = W * H div sizeof(int)

var
frame = 0
bits: array[SLen, uint]
last, start: Time

#---------------------------------------------------------------------------------------------------

proc render() {.cdecl.} =
## Render the window.

var r = bits[0] + 1
for i in countdown(bits.high, 0):
r *= 1103515245
bits[i] = r xor bits[i] shr 16

glClear(GL_COLOR_BUFFER_BIT)
glBitmap(W, H, 0, 0, 0, 0, cast[ptr GLubyte](bits.addr))
glFlush()

inc frame
if (frame and 15) == 0:
let t = getTime()
if t > last:
last = t
echo "fps: ", frame.float / (t - start).inSeconds.float

#---------------------------------------------------------------------------------------------------

proc initGfx(argc: ptr cint; argv: pointer) =
## Initialize OpenGL rendering.

glutInit(argc, argv)
glutInitDisplayMode(GLUT_RGB)
glutInitWindowSize(W, H)
glutIdleFunc(render)
glutDisplayFunc(render)

#———————————————————————————————————————————————————————————————————————————————————————————————————

var argc: cint = 0
start = getTime()
last = start
glutMainLoop()
```

### Using library "Rapid"

Library: rapid

Unfortunately, these examples no longer work for some reason.

Naive implementation:

```import random

import rapid/gfx

var
window = initRWindow()
.size(320, 240)
.title("Rosetta Code - image noise")
.open()
surface = window.openGfx()

surface.loop:
draw ctx, step:
ctx.clear(gray(0))
ctx.begin()
for y in 0..window.height:
for x in 0..window.width:
if rand(0..1) == 0:
ctx.point((x.float, y.float))
ctx.draw(prPoints)
echo 1 / (step / 60)
update step:
```

```import random

import rapid/gfx

var
window = initRWindow()
.size(320, 240)
.title("Rosetta Code - image noise")
.open()
surface = window.openGfx()

let
uniform float time;

float rand(vec2 pos) {
return fract(sin(dot(pos.xy + time, vec2(12.9898,78.233))) * 43758.5453123);
}

vec4 rFragment(vec4 col, sampler2D tex, vec2 pos, vec2 uv) {
return vec4(vec3(step(0.5, rand(uv))), 1.0);
}
""")

surface.vsync = false
surface.loop:
draw ctx, step:
ctx.begin()
ctx.rect(0, 0, surface.width, surface.height)
ctx.draw()
echo 1 / (step / 60)
update step:
```

On a Ryzen 5 1600 and a Vega 56 the naive implementation struggles to maintain 10 FPS. The GPU-powered version, however, reaches up to 12000-13000 FPS.

## OCaml

Library: OCamlSDL

with the ocaml-sdl bindings:

```let frames =
{ contents = 0 }

let t_acc =
{ contents = 0 }

let last_t =
{ contents = Sdltimer.get_ticks () }

let print_fps () =
let t = Sdltimer.get_ticks () in
let dt = t - !last_t in
t_acc := !t_acc + dt;
if !t_acc > 1000 then begin
let el_time = !t_acc / 1000 in
Printf.printf
"- fps: %g\n%!"
(float !frames /. float el_time);
t_acc := 0;
frames := 0;
end;
last_t := t

let blit_noise surf =
let ba = Sdlvideo.pixel_data_8 surf in
let dim = Bigarray.Array1.dim ba in
while true do
for i = 0 to pred dim do
ba.{i} <- if Random.bool () then max_int else 0
done;
Sdlvideo.flip surf;
incr frames;
print_fps ()
done

let blit_noise surf =
try blit_noise surf
with _ -> Sdl.quit ()

let () =
Sdl.init [`VIDEO; `TIMER];
Random.self_init();
let surf =
Sdlvideo.set_video_mode
~w:320 ~h:240 ~bpp:8
[(*`HWSURFACE;*) `DOUBLEBUF]
in
Sys.catch_break true;
blit_noise surf
```

compile to native-code with:

```ocamlopt bigarray.cmxa -I +sdl sdl.cmxa noise_fps_sdl.ml -o noise_fps_sdl.opt
```

or using findlib:

```ocamlfind opt -linkpkg -package sdl noise_fps_sdl.ml
./a.out
```

compile to bytecode with:

```ocamlc bigarray.cma -I +sdl sdl.cma noise_fps_sdl.ml -o noise_fps_sdl.byte
```

In script mode, run with:

```ocaml bigarray.cma -I +sdl sdl.cma noise_fps_sdl.ml
```

In a more idiomatic way, using the modules Graphics and Unix from the standard OCaml library:

```open Graphics

let white = (rgb 255 255 255)
let black = (rgb 0 0 0)

let t_last = ref (Unix.gettimeofday())

let () =
open_graph "";
let width = 320
and height = 240 in
resize_window width height;
try
while true do
for y = 0 to pred height do
for x = 0 to pred width do
set_color (if Random.bool() then white else black);
plot x y
done;
done;
let t = Unix.gettimeofday() in
Printf.printf "- fps: %f\n" (1.0 /. (t -. !t_last));
t_last := t
done
with _ ->
flush stdout;
close_graph ()
```

run this script with:

```ocaml unix.cma graphics.cma g.ml
```

And using an OCaml-Xlib bindings, or an OCaml-Allegro binding.

Equivalent of the C-OpenGL method.

## Pascal

Works with: Free_Pascal
Library: SDL

It is SDL-internally limited to 200 fps.

```Program ImageNoise;

uses
SDL;

var
surface: PSDL_Surface;
pixel: ^byte;
frameNumber, totalTime, lastTime, time, i: longint;

begin
totalTime   := 0;
lastTime    := 0;
randomize;
SDL_Init(SDL_INIT_TIMER or SDL_INIT_VIDEO);
surface := SDL_SetVideoMode(320, 240, 8, SDL_DOUBLEBUF or SDL_HWSURFACE);

while (true) do
begin
pixel := surface^.pixels;
SDL_LockSurface(surface);
for i := 1 to (surface^.w * surface^.h) do
begin
pixel^ := random(2)*255;
inc(pixel);
end;
SDL_UnlockSurface(surface);
SDL_Flip(surface);

time := SDL_GetTicks();
totalTime := totalTime + time - lastTime;
if (totalTime > 1000) then
begin
writeln('FPS: ', frameNumber / (totalTime / 1000.0):5:1);
totalTime := 0;
end;
lastTime := time;
end;
end.
```

## Perl

```use Gtk3 '-init';
use Glib qw/TRUE FALSE/;
use Time::HiRes qw/ tv_interval gettimeofday/;

my \$time0 = [gettimeofday];
my \$frames = -8; # account for set-up steps before drawing

my \$window = Gtk3::Window->new();
\$window->set_default_size(320, 240);
\$window->set_border_width(0);
\$window->set_title("Image_noise");
\$window->set_app_paintable(TRUE);

my \$da = Gtk3::DrawingArea->new();
\$da->signal_connect('draw' => \&draw_in_drawingarea);
\$window->show_all();

Gtk3->main;

sub draw_in_drawingarea {
my (\$widget, \$cr, \$data) = @_;
\$cr->set_line_width(1);
for \$x (1..320) {
for \$y (1..240) {
int rand 2 ? \$cr->set_source_rgb(0, 0, 0) : \$cr->set_source_rgb(1, 1, 1);
\$cr->rectangle( \$x, \$y, 1, 1);
\$cr->stroke;
}
}
}

sub update {
\$da->queue_draw;
my \$elapsed = tv_interval( \$time0, [gettimeofday] );
\$frames++;
printf "fps: %.1f\n", \$frames/\$elapsed if \$frames > 5;
return TRUE;
}
```

## Phix

Library: Phix/pGUI

Not optimised, gets about 130 fps.

```-- demo\rosetta\ImageNoise.exw
include pGUI.e

Ihandle dlg, canvas, timer
cdCanvas cddbuffer, cdcanvas

constant TITLE = "Image noise"

integer fps = 129   -- (typical value)

function redraw_cb(Ihandle /*ih*/, integer /*posx*/, integer /*posy*/)
integer {w, h} = IupGetIntInt(canvas, "DRAWSIZE")
cdCanvasActivate(cddbuffer)
sequence bw = repeat(0,w*h)
for x=0 to w-1 do
for y=0 to h-1 do
if rand(2)=2 then bw[x*h+y+1] = 255 end if
end for
end for
cdCanvasPutImageRectRGB(cddbuffer, w, h, {bw,bw,bw})
cdCanvasFlush(cddbuffer)
fps += 1
return IUP_DEFAULT
end function

atom t1 = time()

function timer_cb(Ihandle /*ih*/)
if time()>t1 then
IupSetStrAttribute(dlg, "TITLE", "%s [%g FPS])",{TITLE,fps})
fps = 0
t1 = time()+1
end if
IupUpdate(canvas)
return IUP_IGNORE
end function

function map_cb(Ihandle ih)
cdcanvas = cdCreateCanvas(CD_IUP, ih)
cddbuffer = cdCreateCanvas(CD_DBUFFER, cdcanvas)
return IUP_DEFAULT
end function

procedure main()
IupOpen()

canvas = IupCanvas(NULL)
IupSetAttribute(canvas, "RASTERSIZE", "320x240")
IupSetCallback(canvas, "MAP_CB", Icallback("map_cb"))
IupSetCallback(canvas, "ACTION", Icallback("redraw_cb"))

timer = IupTimer(Icallback("timer_cb"), 10)

dlg = IupDialog(canvas)
IupSetAttribute(dlg, "TITLE", TITLE)

IupShow(dlg)
IupSetAttribute(canvas, "RASTERSIZE", NULL)
IupMainLoop()
IupClose()
end procedure

main()
```

## PicoLisp

This solution works on ErsatzLisp, the Java version of PicoLisp. It creates a 'JFrame' window, and calls inlined Java code to handle the image.

```(javac "ImageNoise" "JPanel" NIL
"java.util.*"
"java.awt.*" "java.awt.image.*" "javax.swing.*" )

int DX, DY;
int[] Pixels;
MemoryImageSource Source;
Image Img;
Random Rnd;

public ImageNoise(int dx, int dy) {
DX = dx;
DY = dy;
Pixels = new int[DX * DY];
Source = new MemoryImageSource(DX, DY, Pixels, 0, DX);
Source.setAnimated(true);
Img = createImage(Source);
Rnd = new Random();
}

public void paint(Graphics g) {update(g);}
public void update(Graphics g) {g.drawImage(Img, 0, 0, this);}

public void draw() {
for (int i = 0; i < Pixels.length; ++i) {
int c = Rnd.nextInt(255);
Pixels[i] = 0xFF000000 | c<<16 | c<<8 | c;
}
Source.newPixels();
paint(getGraphics());
}
/**/

(de imageNoise (DX DY Fps)
(let
(Frame (java "javax.swing.JFrame" T "Image Noise")
Noise (java "ImageNoise" T DX DY)
Button (java "javax.swing.JButton" T "OK") )
(interface "java.awt.event.ActionListener"
'actionPerformed '((Ev) (bye)) ) )
(java Frame "setSize" DX DY)
(java Frame "setVisible" T)
Image Noise
(java Image "draw") ) ) )

(imageNoise 320 240 25)```

## PL/I

```Image_Noise: procedure options (main); /* 3 November 2013 */
declare (start_time, end_time) float (18);
declare (frame, m, n) fixed binary;

start_time = secs();
get (m, n);
do frame = 1 to 100; /* Generate 100 frames. */
call display (m, n);
put skip data (frame);
end;
end_time = secs();

put skip list ('Average FPS =' || fixed(100/(end_time-start_time), 6) );

display: procedure (m, n);
declare (m, n) fixed binary;
declare screen(0:m, 0:n) bit (1);
declare i fixed binary;
declare random builtin;

screen = '0'b; /* clear screen for this frame */
do i = 0 to m*n*random;
screen(random*m, random*n) = random > 0.5;
end;
end display;

end Image_Noise;
```

## Processing

```color black = color(0);
color white = color(255);

void setup(){
size(320,240);
// frameRate(300); // 60 by default
}

void draw(){
for(int i=0; i<pixels.length; i++){
if(random(1)<0.5){
pixels[i] = black;
}else{
pixels[i] = white;
}
}
updatePixels();
fill(0,128);
rect(0,0,60,20);
fill(255);
text(frameRate, 5,15);
}```

### Processing Python mode

```black = color(0)
white = color(255)

def setup():
size(320, 240)
# frameRate(30) # 60 by default

def draw():
for i in range(len(pixels)):
if random(1) < 0.5:
pixels[i] = black
else:
pixels[i] = white

updatePixels()
fill(0, 128)
rect(0, 0, 60, 20)
fill(255)
text(frameRate, 5, 15)
```

## PureBasic

```#filter=0.2       ; Filter parameter for the FPS-calculation
#UpdateFreq=100   ; How often to update the FPS-display

OpenWindow(0,400,300,320,240,"PureBasic")
Define w=WindowWidth(0), h=WindowHeight(0)
Define x, y, T, TOld, FloatingMedium.f, cnt
InitSprite()
OpenWindowedScreen(WindowID(0),0,0,w,h,1,0,0,#PB_Screen_NoSynchronization)
Repeat
StartDrawing(ScreenOutput())
For y=0 To h-1
For x=0 To w-1
If Random(1)
Plot(x,y,#Black)
Else
Plot(x,y,#White)
EndIf
Next
Next
StopDrawing()
FlipBuffers()
cnt+1
If cnt>=#UpdateFreq
cnt =0
TOld=T
T   =ElapsedMilliseconds()
FloatingMedium*(1-#filter)+1000*#filter/(T-TOld)
SetWindowTitle(0,"PureBasic: "+StrF(#UpdateFreq*FloatingMedium,2)+" FPS")
Repeat ; Handle all events
Event=WindowEvent()
If Event=#PB_Event_CloseWindow
End
EndIf
Until Not Event
EndIf
ForEver```

## Python

Library: Tkinter
Library: PIL
```import time
import random
import tkinter
from PIL import Image
from PIL import ImageTk

class App:
def __init__(self, size, root):
self.root = root
self.root.title("Image Noise Test")

self.img = Image.new("1", size)
self.label = tkinter.Label(root)
self.label.pack()

self.time = 0.0
self.frames = 0
self.size = size
self.n_pixels = self.size[0] * self.size[1]

self.loop()

def loop(self):
start_time = time.time()

self.img.putdata(
[255 if b > 127 else 0 for b in random.randbytes(self.n_pixels)]
)

self.bitmap_image = ImageTk.BitmapImage(self.img)
self.label["image"] = self.bitmap_image

end_time = time.time()
self.time += end_time - start_time
self.frames += 1

if self.frames == 30:
try:
fps = self.frames / self.time
except ZeroDivisionError:
fps = "INSTANT"

print(f"{self.frames} frames in {self.time:3.2f} seconds ({fps} FPS)")
self.time = 0
self.frames = 0

self.root.after(1, self.loop)

def main():
root = tkinter.Tk()
app = App((320, 240), root)
root.mainloop()

if __name__ == "__main__":
main()
```

## Racket

```#lang racket
(require 2htdp/image 2htdp/universe)

(define black (color   0   0   0 255))
(define white (color 255 255 255 255))

(define-struct world (last fps))

(define (noise w h)
(color-list->bitmap
(for*/list ([x (in-range w)] [y (in-range h)])
(if (zero? (random 2)) black white))
w h))

(define (draw w)
(underlay/xy
(noise 320 240) 0 0
(text (number->string (world-fps w)) 64 "Red")))

(define (handle-tick w)
(define cm (current-inexact-milliseconds))
(make-world cm (exact-floor (/ 1000.0 (- cm (world-last w))))))

(big-bang (make-world 1 0)
[on-draw draw]
[on-tick handle-tick (/ 1. 120)])
```

## Raku

(formerly Perl 6) Variant of a script packaged with the SDL2::Raw module.

```use NativeCall;
use SDL2::Raw;

my int (\$w, \$h) = 320, 240;

SDL_Init(VIDEO);

my SDL_Window \$window = SDL_CreateWindow(
"White Noise - Raku",
\$w, \$h,
RESIZABLE
);

my SDL_Renderer \$renderer = SDL_CreateRenderer( \$window, -1, ACCELERATED +| TARGETTEXTURE );

my \$noise_texture = SDL_CreateTexture(\$renderer, %PIXELFORMAT<RGB332>, STREAMING, \$w, \$h);

my \$pixdatabuf = CArray[int64].new(0, \$w, \$h, \$w);

sub render {
my int \$pitch;
my int \$cursor;

# work-around to pass the pointer-pointer.
my \$pixdata = nativecast(Pointer[int64], \$pixdatabuf);
SDL_LockTexture(\$noise_texture, SDL_Rect, \$pixdata, \$pitch);

\$pixdata = nativecast(CArray[int8], Pointer.new(\$pixdatabuf[0]));

loop (my int \$row; \$row < \$h; \$row = \$row + 1) {
loop (my int \$col; \$col < \$w; \$col = \$col + 1) {
\$pixdata[\$cursor + \$col] = Bool.roll ?? 0xff !! 0x0;
}
\$cursor = \$cursor + \$pitch;
}

SDL_UnlockTexture(\$noise_texture);

SDL_RenderCopy(\$renderer, \$noise_texture, SDL_Rect, SDL_Rect);
SDL_RenderPresent(\$renderer);
}

my \$event = SDL_Event.new;

main: loop {

while SDL_PollEvent(\$event) {
my \$casted_event = SDL_CastEvent(\$event);

given \$casted_event {
when *.type == QUIT {
last main;
}
}
}

render();
print fps;
}

say '';

sub fps {
state \$fps-frames = 0;
state \$fps-now    = now;
state \$fps        = '';
\$fps-frames++;
if now - \$fps-now >= 1 {
\$fps = [~] "\b" x 40, ' ' x 20, "\b" x 20 ,
sprintf "FPS: %5.2f  ", (\$fps-frames / (now - \$fps-now)).round(.01);
\$fps-frames = 0;
\$fps-now = now;
}
\$fps
}
```

## REXX

```/*REXX program times (elapsed) the generation of 100 frames of random black&white image.*/
parse arg sw sd im .                             /*obtain optional args from the C.L.   */
if sw=='' | sw==","  then sw=320                 /*SW  specified?  No, then use default.*/
if sd=='' | sd==","  then sd=240                 /*SD      "        "    "   "      "   */
if im=='' | im==","  then im=100                 /*IM      "        "    "   "      "   */
call time 'R'                                    /*reset the REXX elapsed (clock) timer.*/
do   im                            /*generate    IM     number of images. */
call genFrame  sw, sd              /*generate single image of size SW x SD*/
/*■■■ display frame here ■■■*/     /*do (or don't) display the frame num. */
end   /*im*/                       /*generate, but don't display the image*/
/*measures  ↓  elapsed time in seconds.*/
say 'The average frames/second: '    format(im/time("E"), , 2)     /*show frames/second.*/
exit                                             /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
genFrame:  parse arg x,y;   @.0= 'ff000000'x                   /*hex: the color  black. */
@.1= 'ffFFffFF'x                   /* "    "    "    white. */
\$=                                                  /*nullify image string.  */
do y;  _=                                    /*nullify an output row. */
do x;  ?=random(0,1);  _=_ || @.?  /*color is black │ white.*/
end   /*x*/                        /* [↑]  build a whole row*/
\$=\$ || _                                     /*append row to \$ string.*/
end             /*y*/                        /* [↑]  build the image. */
return
```

## RPL

RPL can only handle 131x64 screens. Despite such a small size, displaying graphics is very slow: FPH (frames Per Hour) would be a more appropriate unit.

#### HP 28/48 version

```≪ TICKS (0,0) PMIN (130,64) PMAX
DO
CLLCD
IF TICKS OVER - 8192 / B→R THEN
LAST INV 3 DISP END
0 130 FOR x
0 63 FOR y
IF RAND 0.5 > THEN x y R→C PIXEL END
NEXT NEXT
UNTIL 0 END
≫ 'NOISE' STO
```

HP-28 users shall replace `TICKS` by a `SYSEVAL` call, which address value depends on their ROM version.

#### HP-48G version

From the HP-48G model, the graphics system has been completely reviewed, and so the commands:

```≪ TICKS
DO
ERASE
IF TICKS OVER - 8192 / B→R THEN
LASTARG INV 1 →GROB PICT RCL {#0h #42h} ROT GOR PICT STO {#0 #0} PVIEW END
0 130 FOR x
0 63 FOR y
IF RAND 0.5 > THEN x R→B y R→B 2 →LIST PIXON END
NEXT NEXT
{#0 #0} PVIEW
UNTIL 0 END
≫ 'NOISE' STO
```

FPS = 0.0095

## Ruby

Library: rubygems
Library: ruby-opengl
```require 'rubygems'
require 'gl'
require 'glut'

W, H = 320, 240
SIZE = W * H

Glut.glutInit ARGV
Glut.glutInitWindowSize W, H

Glut.glutIdleFunc lambda {
i = Time.now
noise = (1..SIZE).map { rand > 0.5 ? 0xFFFFFFFF : 0xFF000000 }.pack("I*")

Gl.glClear Gl::GL_COLOR_BUFFER_BIT
Gl.glDrawPixels W, H, Gl::GL_RGBA, Gl::GL_UNSIGNED_BYTE, noise
Gl.glFlush

puts 1.0 / (Time.now - i)
}

Glut.glutCreateWindow "noise"
Glut.glutMainLoop
```
Library: rubygems
Library: JRubyArt

JRubyArt is a port of processing to ruby.

```PALLETE = %w[#000000 #FFFFFF]
def settings
size(320, 240)
end

def setup
sketch_title 'Image Noise'
@black = color(PALLETE[0])
@white = color(PALLETE[1])
@dim = width * height
end

def draw
dim.times { |idx| pixels[idx] = (rand < 0.5) ? black : white }
update_pixels
fill(0, 128)
rect(0, 0, 60, 20)
fill(255)
text(frame_rate, 5, 15)
end
```

## Run BASIC

```begSec = time\$("seconds")
graphic #g, 320,240
tics  = 320 * 240
for i = 1 to tics
x = int((rnd(1) * 320) + 1)
y = int((rnd(1) * 240) + 1)
if int(x mod 2) then  #g "color black ; set "; x; " "; y else #g "color white ; set "; x; " "; y
next i
endSec = time\$("seconds")
totSec = endSec - begSec
print "Seconds;";totSec;" Count:";tics;" Tics / sec:";tics/totSec;" fps:";1/totSec
render #g
#g "flush"```

## Scala

This is basically the same as the Java version, except without using BufferedImage.

```import java.awt.event.{ActionEvent, ActionListener}
import swing.{Panel, MainFrame, SimpleSwingApplication}
import javax.swing.Timer
import java.awt.{Font, Color, Graphics2D, Dimension}

object ImageNoise extends SimpleSwingApplication {
var delay_ms = 2
var framecount = 0
var fps = 0

def top = new MainFrame {
contents = panel
}

val panel = new Panel {
preferredSize = new Dimension(320, 240)

override def paintComponent(g: Graphics2D) {
for (x <- 0 to size.width; y <- 0 to size.height) {
val c = if (math.random > 0.5) Color.BLACK else Color.WHITE
g.setColor(c)
g.fillRect(x, y, 1, 1)
}
g.setColor(Color.RED)
g.setFont(new Font("Monospaced", Font.BOLD, 20))
g.drawString("FPS: " + fps, size.width - 100, size.height - 10)
framecount += 1
}
}

val repainter = new Timer(delay_ms, new ActionListener {
def actionPerformed(e: ActionEvent) {
panel.repaint
}
})

val framerateChecker = new Timer(1000, new ActionListener {
def actionPerformed(e: ActionEvent) {
fps = framecount
framecount = 0
}
})

repainter.start()
framerateChecker.start()
}
```

## Tcl

Library: Tk
```package require Tk

proc generate {img width height} {
set data {}
for {set i 0} {\$i<\$height} {incr i} {
set line {}
for {set j 0} {\$j<\$width} {incr j} {
lappend line [lindex "#000000 #FFFFFF" [expr {rand() < 0.5}]]
}
lappend data \$line
}
\$img put \$data
}

set time 0.0
set count 0

proc looper {} {
global time count
set t [lindex [time {generate noise 320 240}] 0]
set time [expr {\$time + \$t}]
if {[incr count] >= 30} {
set time [expr {\$time / 1000000.0}]
set fps [expr {\$count / \$time}]
puts [format "%d frames in %3.2f seconds (%f FPS)" \$count \$time \$fps]
set time 0.0
set count 0
}
after 1 looper
}

image create photo noise -width 320 -height 240
pack [label .l -image noise]
update
looper
```

## Visual Basic .NET

Windows Forms Application.

```Imports System.Drawing.Imaging

Public Class frmSnowExercise
Dim bRunning As Boolean = True

Private Sub Form1_Load(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles MyBase.Load

' Tell windows we want to handle all the painting and that we want it
'  to double buffer the form's rectangle (Double Buffering
'  removes/ reduces flickering).
SetStyle(ControlStyles.AllPaintingInWmPaint Or ControlStyles.UserPaint _
Or ControlStyles.OptimizedDoubleBuffer, True)

' Prevent the user from resizing the window. Our draw code is not
' setup to recalculate on the fly.
FormBorderStyle = Windows.Forms.FormBorderStyle.FixedSingle
MaximizeBox = False

' The window size and the client rectangle aren't the same.
' To get the proper dimensions for our exercise we need to
' figure out the difference and add it to our 320x240
' requirement.
Width = 320 + Size.Width - ClientSize.Width
Height = 240 + Size.Height - ClientSize.Height

' Pop the window, bring it to the front and give windows time to
' reflect the changes.
Show()
Activate()
Application.DoEvents()

' Hit the loop and keep going until we receive a close request.
RenderLoop()

' We're done. Exit the application.
Close()

End Sub

Private Sub Form1_KeyPress(ByVal sender As Object, ByVal e As _
System.Windows.Forms.KeyPressEventArgs) Handles Me.KeyPress
' Close the application when the user hits escape.
If e.KeyChar = ChrW(Keys.Escape) Then bRunning = False
End Sub

Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As _
System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
' We'll cancel the form close request if we're still running so we
' don't get an error during runtime and set the close request flag.
e.Cancel = bRunning
bRunning = False
End Sub

Private Sub RenderLoop()

Const cfPadding As Single = 5.0F

Dim b As New Bitmap(ClientSize.Width, ClientSize.Width,
PixelFormat.Format32bppArgb)
Dim g As Graphics = Graphics.FromImage(b)
Dim r As New Random(Now.Millisecond)
Dim oBMPData As BitmapData = Nothing
Dim oPixels() As Integer = Nothing
Dim oBlackWhite() As Integer = {Color.White.ToArgb, Color.Black.ToArgb}
Dim oStopwatch As New Stopwatch
Dim fElapsed As Single = 0.0F
Dim iLoops As Integer = 0
Dim sFPS As String = "0.0 FPS"
Dim oFPSSize As SizeF = g.MeasureString(sFPS, Font)
Dim oFPSBG As RectangleF = New RectangleF(ClientSize.Width - cfPadding -

' Get ourselves a nice, clean, black canvas to work with.
g.Clear(Color.Black)

' Prep our bitmap for a read.
oBMPData = b.LockBits(New Rectangle(0, 0, b.Width, b.Height),

' Allocate sufficient space for the pixel data and
' flash copy it to our array.
' We want an integer to hold the color for each pixel in the canvas.
Array.Resize(oPixels, b.Width * b.Height)
Runtime.InteropServices.Marshal.Copy(oBMPData.Scan0,
oPixels, 0, oPixels.Length)
b.UnlockBits(oBMPData)
' Start looping.
Do
' Find our frame time and add it to the total amount of time
' elapsed since our last FPS update (once per second).
fElapsed += oStopwatch.ElapsedMilliseconds / 1000.0F
oStopwatch.Reset() : oStopwatch.Start()
' Adjust the number of loops since the last whole second has elapsed
iLoops += 1
If fElapsed >= 1.0F Then
' Since we've now had a whole second elapse
' figure the Frames Per Second,
' measure our string,
' setup our backing rectangle for the FPS string
'        (so it's clearly visible over the snow)
' reset our loop counter
' and our elapsed counter.
sFPS = (iLoops / fElapsed).ToString("0.0") & " FPS"
oFPSSize = g.MeasureString(sFPS, Font)
oFPSBG = New RectangleF(ClientSize.Width - cfPadding -
' We don't set this to 0 in case our frame time has gone
'  a bit over 1 second since last update.
fElapsed -= 1.0F
iLoops = 0
End If

' Generate our snow.
For i As Integer = 0 To oPixels.GetUpperBound(0)
oPixels(i) = oBlackWhite(r.Next(oBlackWhite.Length))
Next

' Prep the bitmap for an update.
oBMPData = b.LockBits(New Rectangle(0, 0, b.Width, b.Height),
ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb)
' Flash copy the new data into our bitmap.
Runtime.InteropServices.Marshal.Copy(oPixels, 0, oBMPData.Scan0,
oPixels.Length)
b.UnlockBits(oBMPData)

' Draw the backing for our FPS display.
g.FillRectangle(Brushes.Black, oFPSBG)
' Draw our FPS.
g.DrawString(sFPS, Font, Brushes.Yellow, oFPSBG.Left, oFPSBG.Top)

' Update the form's background and draw.
BackgroundImage = b
Invalidate(ClientRectangle)

' Let windows handle some queued events.
Application.DoEvents()
Loop While bRunning

End Sub
End Class
```

Sample:

## Wren

Library: DOME
```import "dome" for Window
import "graphics" for Canvas, Color
import "random" for Random

class Game {
static init() {
Window.title = "Image Noise"
__w = 320
__h = 240
Window.resize(__w, __h)
Canvas.resize(__w, __h)
__r = Random.new()
__t = System.clock
}

static update() {}

static draw(dt) {
Canvas.cls() // default background is black
for (x in 0...__w) {
for (y in 0...__h) {
if (__r.int(2) == 0) {
Canvas.pset(x, y, Color.white)
}
}
}
var t = System.clock
var fps = (1/(t - __t)).round
Canvas.print("FPS: %(fps)", 10, 10, Color.red)
__t = t
}
}
```

## XPL0

Measured 102 FPS on a Presario 2100 Notebook Athlon 2500. (The Paint intrinsic could display this image at 327 FPS if Ran(2) was faster.)

```include c:\cxpl\codes;          \intrinsic 'code' declarations
int CpuReg,                     \address of CPU register array (from GetReg)
FPS,                        \frames per second, the display's update rate
Sec,                        \current second of time (from real-time clock)
SecOld,                     \previous second of time
X, Y;
[SetVid(\$101);                  \set 640x480 graphics
CpuReg:= GetReg;                \get address of array to access CPU registers
FPS:= 0;
repeat  CpuReg(0):= \$0200;      \get current time in seconds from BIOS
SoftInt(\$1A);           \software interrupt
Sec:= CpuReg(3)>>8 & \$FF; \register DH contains seconds
if Sec = SecOld then    \if same as before then
FPS:= FPS+1     \ bump FPS counter
else    [SecOld:= Sec;  \otherwise save old seconds and
CrLf(6);
IntOut(6, FPS); \ display FPS counter (once per second)
Text(6, " FPS");
FPS:= 0;        \ reset FPS counter
];
for Y:= 0, 240-1 do     \fill image with random black and white pixels
for X:= 0, 320-1 do
Point(X, Y, if Ran(2) then \$F\white\ else 0\black\);
until KeyHit;
SetVid(3);                      \restore normal text mode
]```

## Z80 Assembly

Works with: Game Boy Color

Omitting the initialization code and the other logic keeping the machine working, this will focus solely on the code responsible for creating the effect. The "random" noise was generated by loading this program's ROM image in YY-CHR (a binary file editor) and copying it to its own file, then loading that file into the Game Boy Color's video memory. The framerate is usually 60 FPS but occasionally dips to 59. At first, every tile on screen is the same, but the "noise" effect is caused by:

• A "frame timer" variable that increments every vertical blank is used as a pseudo-RNG.
• A variable called "cosine_index" is incremented and its cosine is taken, then the screen is scrolled by that amount.
• Each iteration of the main game loop alters the interrupt handler (which is executed in RAM, having been copied from ROM before the main game loop begins) so that the sine is taken rather than the cosine.
• During the main game loop, the frame timer is also used to select a random graphics tile from among 16 possibilities, and draws it to a randomly selected tile on screen using a simple "xor-shift" routine.
```forever:
ld hl,frametimer
ld a,(hl)
rrca
rrca
rrca
xor (hl)	  ;crude xorshift rng used to select a "random" location to draw to.

ld h,0
ld L,a            ;this random value becomes the low byte of HL

rlc L
rl h              ;reduce the RNG's bias towards the top of the screen by shifting one bit into H.
ld a,&98	  ;high byte of gb vram
add h             ;h will equal either 0 or 1.
ld H,a            ;now H will either equal &98 or &99

ld a,(frametimer) ;it's possible that this value is different from before since every vblank it increments.
;the vblank code was omitted because it's mostly irrelevant to the task.
and &0f           ;select one of sixteen tiles to draw to the screen at the randomly chosen VRAM location.
call LCDWait      ;disable interrupts, and wait until the Game Boy is ready to update the tilemap
ei                ;enable interrupts again.
ld (hl),a         ;now we can store the frame timer AND &0F into video ram.

ld hl,vblankflag  ;set to 1 by the vblank routine.
xor a
wait:
halt              ;waits for an interrupt.
cp (hl)           compare 0 to vblankflag
jr z,wait         ;vblank flag is still 1 so keep waiting.
ld (hl),a         ;clear vblank flag.

ld hl,&FFFF       ;master interrupt register
res 1,(hl)        ;disable hblank interrupt.

ld bc,2
ld a,(frametimer)
bit 4,a   ;check bit 4 of frametimer, if zero, we'll do sine instead of cosine. Bit 4 was chosen arbitrarily.
jr nz,doSine
ld hl,cos
jr nowStore
doSine:
ld hl,sin
nowStore:	;store desired routine as the CALL address
ld a,L
LD (&A000+(callpoint-TV_Static_FX+1)),a
;using label arithmetic we can work out the place to modify the code.
;hblank interrupt immediately jumps to cartridge RAM at &A000
ld a,H
LD (&A000+(callpoint-TV_Static_FX+2)),a   ;store the high byte.

ld hl,&FFFF
set 1,(hl)      ;re-enable hblank interrupt

jp forever```

And the interrupt handler located at memory address `&A000`:

```TV_Static_FX:
;this code runs every time the game boy finishes drawing one row of pixels, unless the interrupt is disabled as described above.
push hl
push af
ld hl,(COSINE_INDEX)
inc (hl)
ld a,(hl)

callpoint:
call cos	;<--- SMC, gets changed to "CALL SIN" by main game loop when bit 4 of frametimer equals 0, and back to
;"CALL COS" when bit 4 of frametimer equals 1.
; returns cos(A) into A

LD (&FF43),A    ;output cos(frametimer) to horizontal scroll register
done_TV_Static_FX:
pop af
pop hl