Raster bars
Display bars of color, moving up and down across the screen for horizontal raster bars, or left and right across the screen for vertical raster bars, making the raster bars move as stated by swaying side-to-side the respective way if possible.
- Task
Use multiple colors in succession and carefully make a gradient between the colors (if possible) to achieve an effect of metallic-looking horizontal bars.
Horizontal and/or vertical raster bars are acceptable.
Ada
<lang Ada>with Ada.Numerics.Elementary_Functions;
with SDL.Video.Windows.Makers; with SDL.Video.Renderers.Makers; with SDL.Video.Palettes; with SDL.Events.Events;
procedure Raster_Bars is
Width : constant := 1200; Height : constant := 600;
Window : SDL.Video.Windows.Window; Renderer : SDL.Video.Renderers.Renderer;
function Check_Quit return Boolean is
use type SDL.Events.Event_Types;
Event : SDL.Events.Events.Events;
begin
while SDL.Events.Events.Poll (Event) loop
if Event.Common.Event_Type = SDL.Events.Quit then
return True;
end if;
end loop;
return False;
end Check_Quit;
procedure Draw_Raster_Bar (Y : Integer) is
use SDL.Video.Palettes;
use SDL.C;
Cc : Colour_Component;
begin
for I in 0 .. 10 loop
Cc := Colour_Component (50 + 20 * I);
Renderer.Set_Draw_Colour ((Cc, Cc, Cc, 255));
Renderer.Draw (Line => ((0, C.int (Y + I)),
(Width, C.int (Y + I))));
end loop;
end Draw_Raster_Bar;
procedure Draw_Raster_Bar_V (X : Integer) is
use SDL.Video.Palettes;
use SDL.C;
Cc : Colour_Component;
begin
for I in 0 .. 10 loop
Cc := Colour_Component (250 - 20 * I);
Renderer.Set_Draw_Colour ((Cc, Cc, Cc, 255));
Renderer.Draw (Line => ((C.int (X + I), 0),
(C.int (X + I), Height)));
end loop;
end Draw_Raster_Bar_V;
procedure Raster_Bars is
use Ada.Numerics.Elementary_Functions;
Xc : constant Integer := 800;
Yc : constant Integer := 200;
XA : constant Float := 40.0;
YA : constant Float := 30.0;
N : Float := 0.0;
begin
loop
Renderer.Set_Draw_Colour ((0, 0, 0, 255));
Renderer.Fill (Rectangle => (0, 0, Width, Height));
Draw_Raster_Bar (Yc + Integer (YA * Sin (N + 00.0, 360.0)));
Draw_Raster_Bar (Yc + Integer (YA * Sin (N + 25.0, 360.0)));
Draw_Raster_Bar (Yc + Integer (YA * Sin (N + 50.0, 360.0)));
Draw_Raster_Bar (Yc + Integer (YA * Sin (N + 75.0, 360.0)));
Draw_Raster_Bar_V (Xc + Integer (XA * Sin (0.6 * N + 00.0, 360.0)));
Draw_Raster_Bar_V (Xc + Integer (XA * Sin (0.6 * N + 90.0, 360.0)));
Draw_Raster_Bar_V (Xc + Integer (XA * Sin (0.6 * N + 180.0, 360.0)));
Window.Update_Surface;
if Check_Quit then
exit;
end if;
delay 0.010;
N := N + 4.0;
end loop;
end Raster_Bars;
begin
if not SDL.Initialise (Flags => SDL.Enable_Screen) then
return;
end if;
SDL.Video.Windows.Makers.Create (Win => Window,
Title => "Raster bar",
Position => SDL.Natural_Coordinates'(X => 10, Y => 10),
Size => SDL.Positive_Sizes'(Width, Height),
Flags => 0);
SDL.Video.Renderers.Makers.Create (Renderer, Window.Get_Surface);
Raster_Bars;
Window.Finalize; SDL.Finalise;
end Raster_Bars;</lang>
Go
This uses Go's 'image' packages in its standard library to create an animated GIF.
After each 20 frames, it switches between horizontal and vertical bars and repeats the whole process 10 times.
WARNING: If you have problems with flashing images, either switch to a longer delay than 150ms between 'sways' or don't run it at all.
Although the .gif works fine in Firefox it might not do so in EOG due to optimizations made during its creation. If so, then the following ImageMagick command should fix it:
$ convert raster_bars.gif -coalesce raster_bars2.gif $ eog raster_bars2.gif
<lang go>package main
import (
"image" "image/color" "image/gif" "log" "os"
)
var (
c0 = color.RGBA{166, 124, 0, 255}
c1 = color.RGBA{191, 155, 48, 255}
c2 = color.RGBA{255, 191, 0, 255}
c3 = color.RGBA{255, 207, 64, 255}
c4 = color.RGBA{255, 220, 115, 255}
)
var palette = []color.Color{c0, c1, c2, c3, c4}
func hline(img *image.Paletted, x1, y, x2 int, ci uint8) {
for ; x1 <= x2; x1++ {
img.SetColorIndex(x1, y, ci)
}
}
func vline(img *image.Paletted, x, y1, y2 int, ci uint8) {
for ; y1 <= y2; y1++ {
img.SetColorIndex(x, y1, ci)
}
}
func drawHbar(img *image.Paletted, x1, y1, x2, y2 int, ci uint8) {
for ; y1 <= y2; y1++ {
hline(img, x1, y1, x2, ci)
}
}
func drawVbar(img *image.Paletted, x1, y1, x2, y2 int, ci uint8) {
for ; x1 <= x2; x1++ {
vline(img, x1, y1, y2, ci)
}
}
func main() {
const nframes = 40
const delay = 15 // 150ms
width, height := 500, 500
anim := gif.GIF{LoopCount: 9} // repeats 9 + 1 times
rect := image.Rect(0, 0, width, height)
for f := 0; f < nframes; f++ {
img := image.NewPaletted(rect, palette)
c := uint8(f % 2)
if f < nframes/2 {
for y := 0; y < height; y += 20 {
drawHbar(img, 0, y, width, y+19, c)
c++
if c == 5 {
c = 0
}
}
} else {
for x := 0; x < width; x += 20 {
drawVbar(img, x, 0, x+19, height, c)
c++
if c == 5 {
c = 0
}
}
}
anim.Delay = append(anim.Delay, delay)
anim.Image = append(anim.Image, img)
}
file, err := os.Create("raster_bars.gif")
if err != nil {
log.Fatal(err)
}
defer file.Close()
if err2 := gif.EncodeAll(file, &anim); err != nil {
log.Fatal(err2)
}
}</lang>
Julia
<lang julia>using Colors, Cairo, Gtk
const can = GtkCanvas() const win = GtkWindow(can, "Raster Bar Demo", 500, 500) const pallete_index = [1] const horizontal = [true] const palette = [ # colors from the Go example
colorant"rgba(166, 124, 0, 1.0)", colorant"rgba(191, 155, 48, 1.0)", colorant"rgba(255, 191, 0, 1.0)", colorant"rgba(255, 207, 64, 1.0)", colorant"rgba(255, 220, 115, 1.0)",
]
function line(ctx, x1, y1, x2, y2, colr, width=1)
set_source(ctx, colr) set_line_width(ctx, width) move_to(ctx, x1, y1) line_to(ctx, x2, y2) stroke(ctx)
end hline(ctx, x1, y, x2, c) = line(ctx, x1, y, x2, y, c) hbar(ctx, x1, y1, x2, y2, c) = foreach(y -> hline(ctx, x1, y, x2, c), y1:y2) vline(ctx, x, y1, y2, c) = line(ctx, x, y1, x, y2, c) vbar(ctx, x1, y1, x2, y2, c) = foreach(x -> vline(ctx, x, y1, y2, c), x1:x2)
draw(can) do widget
ctx = Gtk.getgc(can)
height, width = Gtk.height(can), Gtk.width(can)
if horizontal[1]
for i in 1:3:height
hbar(ctx, 0, i, width, i + 3, palette[pallete_index[1]])
pallete_index[1] = mod1(pallete_index[1] + 1, 5)
end
else
for i in 1:3:width
vbar(ctx, i, 0, i + 3, height, palette[pallete_index[1]])
pallete_index[1] = mod1(pallete_index[1] + 1, 5)
end
end
end
set_gtk_property!(can, :expand, true) for i in 1:typemax(Int)
sleep(0.1)
draw(can)
showall(win)
pallete_index[1] = mod1(pallete_index[1] + 2, 5)
if i % 30 == 29
horizontal[1] = !horizontal[1]
end
end </lang>
Nim
<lang Nim>import gintro/[gobject, glib, gdk, gtk, gio, cairo]
const Palette = [[166.0, 124.0, 0.0],
[191.0, 155.0, 48.0],
[255.0, 191.0, 0.0],
[255.0, 207.0, 64.0],
[255.0, 220.0, 115.0]]
type
# Description of the simulation. Simulation = ref object area: DrawingArea horizontal: bool paletteIndex: Natural count: int
Color = array[3, float]
- ---------------------------------------------------------------------------------------------------
proc newSimulation(area: DrawingArea): Simulation {.noInit.} =
## Allocate and initialize the simulation object. Simulation(area: area, horizontal: true, paletteIndex: 0, count: 0)
- ---------------------------------------------------------------------------------------------------
proc bar(ctx: cairo.Context; x1, y1, x2, y2: int; c: Color) =
## Draw a bar. ctx.setSource(c) ctx.rectangle(x1.toFloat, y1.toFloat, (x2 - x1 + 1).toFloat, (y2 - y1 + 1).toFloat) ctx.fill()
- ---------------------------------------------------------------------------------------------------
proc draw(sim: Simulation; ctx: cairo.Context) =
## Draw the bars.
let width = sim.area.window.width() let height = sim.area.window.height()
if sim.horizontal:
for i in countup(0, height - 4, 3):
ctx.bar(0, i, width - 1, i + 3, Palette[sim.paletteIndex])
sim.paletteIndex = (sim.paletteIndex + 1) mod 5
else:
for i in countup(0, width - 4, 3):
ctx.bar(i, 0, i + 3, height - 1, Palette[sim.paletteIndex])
sim.paletteIndex = (sim.paletteIndex + 1) mod 5
- ---------------------------------------------------------------------------------------------------
proc update(sim: Simulation): gboolean =
## Update the simulation state.
sim.draw(sim.area.window.cairoCreate()) sim.area.showAll() sim.paletteIndex = (sim.paletteIndex + 2) mod 5 inc sim.count if sim.count mod 30 == 29: sim.horizontal = not sim.horizontal result = gboolean(1)
- ---------------------------------------------------------------------------------------------------
proc activate(app: Application) =
## Activate the application.
let window = app.newApplicationWindow()
window.setSizeRequest(500, 500)
window.setTitle("Raster Bar Demo")
let area = newDrawingArea() window.add(area)
let sim = newSimulation(area) timeoutAdd(50, update, sim)
window.showAll()
- ———————————————————————————————————————————————————————————————————————————————————————————————————
let app = newApplication(Application, "Rosetta.rasterbars") discard app.connect("activate", activate) discard app.run()</lang>
Phix
Some grey bars that vaguely shimmer as they march up the screen... (did not turn out quite as well as hoped) <lang Phix>-- demo\rosetta\Raster_bars.exw constant N = 10,
nColours = floor(255/N)
integer offset = 0, clast = nColours
include pGUI.e
Ihandle dlg, canvas cdCanvas cddbuffer, cdcanvas
function colour(integer i)
integer g = i*N return cdEncodeColorAlpha(g, g, g, 255)
end function
function redraw_cb(Ihandle /*ih*/, integer /*posx*/, integer /*posy*/)
cdCanvasActivate(cddbuffer)
cdCanvasSetBackground(cddbuffer, colour(clast))
cdCanvasClear(cddbuffer)
integer {width, height} = IupGetIntInt(canvas, "DRAWSIZE"),
h = floor(height/(nColours-1)),
y = height+offset
cdCanvasSetInteriorStyle(cddbuffer, CD_SOLID)
for i=2 to nColours do
integer c = clast+i-1
if c>nColours then c -= nColours end if
cdCanvasSetForeground(cddbuffer, colour(c))
cdCanvasBox(cddbuffer, 0, width, y-h, y)
y -= h
end for
cdCanvasFlush(cddbuffer)
offset += 1
if offset>=h then
offset = 0
clast += 1
if clast>nColours then clast = 1 end if
end if
return IUP_DEFAULT
end function
function map_cb(Ihandle ih)
cdcanvas = cdCreateCanvas(CD_IUP, ih) cddbuffer = cdCreateCanvas(CD_DBUFFER, cdcanvas) return IUP_DEFAULT
end function
function unmap_cb(Ihandle /*ih*/)
cdKillCanvas(cddbuffer) cdKillCanvas(cdcanvas) return IUP_DEFAULT
end function
function timer_cb(Ihandle /*ih*/)
IupRedraw(dlg) return IUP_DEFAULT
end function
procedure main()
IupOpen()
canvas = IupCanvas(NULL)
IupSetAttribute(canvas, "RASTERSIZE", "600x400")
IupSetCallback(canvas, "MAP_CB", Icallback("map_cb"))
IupSetCallback(canvas, "UNMAP_CB", Icallback("unmap_cb"))
dlg = IupDialog(canvas)
IupSetAttribute(dlg, "TITLE", "Raster bars")
IupSetCallback(canvas, "ACTION", Icallback("redraw_cb"))
Ihandle hTimer = IupTimer(Icallback("timer_cb"), 10)
IupMap(dlg)
IupSetAttribute(canvas, "RASTERSIZE", NULL)
IupShowXY(dlg,IUP_CENTER,IUP_CENTER)
IupMainLoop()
IupClose()
end procedure
main()</lang>
Raku
(formerly Perl 6)
As there is no reference implementation, and rather sketchy task instructions, this may or may not fulfill the original task authors intent.
Not really sure what is meant by "swaying", perhaps this will suffice.
Generate random colored bars and display them. (They ended up looking more plastic than metallic; ah well.)
- Use Up / Down arrows to change the scroll speed.
- Use Left / Right arrows to adjust the gap between the raster bars.
- Use Pg Up / Pg Dn to adjust raster bar height.
- Use Z / X to change the angle of the raster bars.
- Use Space bar to pause / resume scrolling.
- Use Left Ctrl to toggle the scroll direction.
- Press R to toggle Randomize on / off.
- If Randomize is active, adjust the randomize delay with < / >
- Press S to toggle Swaying on / off.
- If Swaying is active, adjust the period with D / F
- Press Q to exit.
<lang perl6>unit sub MAIN (
Int :b(:$bar-height) is copy = 60; #= Height of the individual "Raster bars", minimum 32 (pixels) Int :d(:$dir) is copy = -1; #= Scroll direction: -1 is "up" 1 is "down" Int :s(:$step) is copy = 4; #= Scroll speed (pixels per step Int :g(:$gap) is copy = $bar-height + 50; #= Gap between bars (pixels) Int :a(:$angle) is copy = 0; #= Angle to orient bars off horizontal (-60 to 60 degrees) Int :sw(:$sway) is copy = 0; #= Swaying on / off Real :r(:$rnd) is copy = 0; #= Delay between randomize events
);
say q:to/END/;
Use Up / Down arrows to change the scroll speed. Use Left / Right arrows to adjust the gap between the raster bars. Use Pg Up / Pg Dn to adjust raster bar height. Use Z / X to change the angle of the raster bars. Use Space bar to pause / resume scrolling. Use Left Ctrl to toggle the scroll direction. Press R to toggle Randomize on / off. If Randomize is active, adjust the randomize delay with < / > Press S to toggle Swaying on / off. If Swaying is active, adjust the period with D / F Press Q to exit. END
use SDL2::Raw; use Cairo;
my $width = 800; my $height = 800;
SDL_Init(VIDEO);
my $window = SDL_CreateWindow(
'Raster Bars - Raku', SDL_WINDOWPOS_CENTERED_MASK, SDL_WINDOWPOS_CENTERED_MASK, $width, $height, RESIZABLE
);
my $render = SDL_CreateRenderer($window, -1, ACCELERATED +| PRESENTVSYNC);
my @bars = (^128).map: { gen-bar( rand xx 3 ) };
my $event = SDL_Event.new;
enum KEY_CODES (
K_UP => 82, K_DOWN => 81, K_LEFT => 80, K_RIGHT => 79, K_SPACE => 44, K_PGUP => 75, K_PGDN => 78, K_LCTRL => 224, K_Z => 29, K_X => 27, K_Q => 20, K_R => 21, K_S => 22, K_D => 7, K_F => 9, K_LT => 54, K_GT => 55,
);
my $port = +@bars * $gap; my $y = $dir > 0 ?? $height - $port !! $height ; my $now = now; my $period = 2;
main: loop {
handle-event($event) while SDL_PollEvent($event);
randomize if $rnd and now - $now > $rnd;
if $dir > 0 {
$y = $height - $port if $y > 0 - ceiling $height / cos(π * $angle / 180).abs
} else {
$y = 0 - ceiling $height / cos(π * $angle / 180).abs if $y < $height - $port
}
$y = $step * $dir + $y;
$angle = (((now * $period) % τ).sin * 35).Int if $sway;
for ^@bars {
my $offset = $sway ?? $gap !! ceiling $gap / cos(π * $angle / 180).abs;
SDL_RenderCopyEx( $render, @bars[$_], Nil,
SDL_Rect.new( -($width*4), $y + $offset * $_, $width * 10, $bar-height),
$angle.Num, SDL_Point.new(:x((4.5*$width).Int),:y($y + $offset * $_)), 0
) }
SDL_RenderPresent($render);
SDL_RenderClear($render);
print fps;
}
put ;
SDL_Quit();
sub gen-bar (@color) {
my $bar = Cairo::Image.create( Cairo::FORMAT_ARGB32, 1, 128 );
given Cairo::Context.new($bar) {
my Cairo::Pattern::Gradient::Linear $lpat .= create(0.0, 0.0, 0.0, 128.0);
$lpat.add_color_stop_rgba( 1, |(@color »*» .3), 1);
$lpat.add_color_stop_rgba( .2, |(@color), 1);
$lpat.add_color_stop_rgba(.75, |(@color), 1);
$lpat.add_color_stop_rgba( 0, |(@color »+» .5), 1);
.rectangle(0, 0, 1, 128);
.pattern($lpat);
.fill;
$lpat.destroy;
}
my $bar_texture = SDL_CreateTexture(
$render, %PIXELFORMAT<ARGB8888>,
STATIC, 1, 128
);
SDL_UpdateTexture(
$bar_texture,
SDL_Rect.new(:x(0), :y(0), :w(1), :h(128)),
$bar.data, $bar.stride // 1
);
$bar_texture
}
sub handle-event ($event) {
my $casted_event = SDL_CastEvent($event);
given $casted_event {
when *.type == QUIT { last main }
when *.type == KEYDOWN {
if KEY_CODES(.scancode) -> $comm {
given $comm {
when 'K_UP' { $step += 1 }
when 'K_DOWN' { $step -= 1 if $step > 1 }
when 'K_LEFT' { $gap = $gap < 32 ?? $gap !! $gap - 1; $port = +@bars * $gap; }
when 'K_RIGHT' { $gap++; $port += +@bars; }
when 'K_PGUP' { $bar-height += 2 }
when 'K_PGDN' { $bar-height = $bar-height >= 34 ?? $bar-height - 2 !! $bar-height }
when 'K_SPACE' { $step = $step ?? 0 !! 1 }
when 'K_LCTRL' { $dir *= -1 }
when 'K_Z' { $angle = $angle > -45 ?? $angle - 5 !! $angle }
when 'K_X' { $angle = $angle < 45 ?? $angle + 5 !! $angle }
when 'K_R' { $rnd = $rnd ?? 0 !! 1 }
when 'K_S' { $sway xor= 1 }
when 'K_F' { $period += .1 }
when 'K_D' { $period = $period - .1 max .1; }
when 'K_GT' { $rnd += .2 }
when 'K_LT' { $rnd = $rnd > .2 ?? $rnd -.2 !! .2 }
when 'K_Q' { last main }
}
} #else { say .scancode, "\n" }
}
when *.type == WINDOWEVENT {
if .event == RESIZED {
$width = .data1;
$height = .data2 + $bar-height;
}
}
}
}
sub randomize {
$dir = (-1,1).pick; $step = (4..8).pick; $bar-height = (32..200).pick; $gap = $bar-height + (1..100).pick; $angle = (-45, *+5 ... 45).pick;
$port = +@bars * $gap;
if $dir > 0 {
$y = $height - $port;
} else {
$y = 0 - ceiling ($height max $width) / cos(π * $angle / 180).abs;
}
$now = now;
}
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
}</lang>
Screenshot still of typical run: (offsite .png image)
(Small) Moving gif of swaying bars: (offsite .gif image)
Wren
Unlike the Go example, repeats indefinitely until the window is closed.
As DOME has no facility to create an animated .gif file, the moving image is displayed but not saved. <lang ecmascript>import "dome" for Window import "graphics" for Canvas, Color
var c0 = Color.rgb(166, 124, 0, 255) var c1 = Color.rgb(191, 155, 48, 255) var c2 = Color.rgb(255, 191, 0, 255) var c3 = Color.rgb(255, 207, 64, 255) var c4 = Color.rgb(255, 220, 115, 255)
var Palette = [c0, c1, c2, c3, c4]
class RasterBars {
construct new(width, height) {
Window.resize(width, height)
Canvas.resize(width, height)
Window.title = "Raster bars"
_width = width
_height = height
}
init() {
_f = 0
_nframes = 320
_draw = false
_c = false
}
hline(x1, y, x2, ci) {
while (x1 <= x2) {
Canvas.pset(x1, y, Palette[ci])
x1 = x1 + 1
}
}
vline(x, y1, y2, ci) {
while (y1 <= y2) {
Canvas.pset(x, y1, Palette[ci])
y1 = y1 + 1
}
}
drawHBar(x1, y1, x2, y2, ci) {
while (y1 <= y2) {
hline(x1, y1, x2, ci)
y1 = y1 + 1
}
}
drawVBar(x1, y1, x2, y2, ci) {
while (x1 <= x2) {
vline(x1, y1, y2, ci)
x1 = x1 + 1
}
}
update() {
_f = _f + 1
if (_f % 8 == 0) {
_draw = true
_c = !_c
} else {
_draw = false
}
if (_f == _nframes) _f = 0
}
draw(alpha) {
if (!_draw) return
var c = _c ? 0 : 1
if (_f < _nframes / 2) {
var y = 0
while (y < _height) {
drawHBar(0, y, _width, y+19, c)
c = (c < 4) ? c + 1 : 0
y = y + 20
}
} else {
var x = 0
while (x < _width) {
drawVBar(x, 0, x+19, _height, c)
c = (c < 4) ? c + 1 : 0
x = x + 20
}
}
}
}
var Game = RasterBars.new(500, 500)</lang>