Brownian tree

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Brownian tree
You are encouraged to solve this task according to the task description, using any language you may know.

Generate and draw a Brownian Tree.

A Brownian Tree is generated as a result of an initial seed, followed by the interaction of two processes.

1. The initial "seed" is placed somewhere within the field. Where is not particularly important; it could be randomized, or it could be a fixed point.
2. Particles are injected into the field, and are individually given a (typically random) motion pattern.
3. When a particle collides with the seed or tree, its position is fixed, and it's considered to be part of the tree.

Because of the lax rules governing the random nature of the particle's placement and motion, no two resulting trees are really expected to be the same, or even necessarily have the same general shape.

C

Library: FreeImage

<lang c>#include <string.h>

1. include <stdlib.h>
2. include <time.h>
3. include <math.h>
4. include <FreeImage.h>

1. define NUM_PARTICLES 1000
2. define SIZE 800

void draw_brownian_tree(int world[SIZE][SIZE]){

 int px, py; // particle values
 int dx, dy; // offsets
 int hit;
 int i;

 // set the seed
 world[rand() % SIZE][rand() % SIZE] = 1;

 for (i = 0; i < NUM_PARTICLES; i++){
   // set particle's initial position
   px = rand() % SIZE;
   py = rand() % SIZE;

   while (1){
     // randomly choose a direction
     dx = rand() % 3 - 1;
     dy = rand() % 3 - 1;

     if (dx + px < 0 || dx + px >= SIZE || dy + py < 0 || dy + py >= SIZE){
       // plop the particle into some other random location
       px = rand() % SIZE;
       py = rand() % SIZE;
     }else if (world[py + dy][px + dx] != 0){
       // bumped into something
       world[py][px] = 1;
       break;
     }else{
       py += dy;
       px += dx;
     }
   }
 }

}

int main(){

 int world[SIZE][SIZE];
 FIBITMAP * img;
 RGBQUAD rgb;
 int x, y;

 memset(world, 0, sizeof world);
 srand((unsigned)time(NULL));

 draw_brownian_tree(world);

 img = FreeImage_Allocate(SIZE, SIZE, 32, 0, 0, 0);

 for (y = 0; y < SIZE; y++){
   for (x = 0; x < SIZE; x++){
     rgb.rgbRed = rgb.rgbGreen = rgb.rgbBlue = (world[y][x] ? 255 : 0);
     FreeImage_SetPixelColor(img, x, y, &rgb);
   }
 }
 FreeImage_Save(FIF_BMP, img, "brownian_tree.bmp", 0);
 FreeImage_Unload(img);

}</lang>

Delphi

<lang delphi>const

   SIZE = 256;
   NUM_PARTICLES = 1000;

procedure TForm1.Button1Click(Sender: TObject); type

   TByteArray = array[0..0] of Byte;
   PByteArray = ^TByteArray;

var

   B: TBitmap;
   I: Integer;
   P, D: TPoint;

begin

   Randomize;
   B := TBitmap.Create;
   try
       B.Width := SIZE;
       B.Height := SIZE;
       B.PixelFormat := pf8bit;

       B.Canvas.Brush.Color := clBlack;
       B.Canvas.FillRect(B.Canvas.ClipRect);
       B.Canvas.Pixels[Random(SIZE), Random(SIZE)] := clWhite;

       For I := 0 to NUM_PARTICLES - 1 do
       Begin
           P.X := Random(SIZE);
           P.Y := Random(SIZE);

           While true do
           Begin
               D.X := Random(3) - 1;
               D.Y := Random(3) - 1;
               Inc(P.X, D.X);
               Inc(P.Y, D.Y);

               If ((P.X or P.Y) < 0) or (P.X >= SIZE) or (P.Y >= SIZE) Then
               Begin
                   P.X := Random(SIZE);
                   P.Y := Random(SIZE);
               end
               else if PByteArray(B.ScanLine[P.Y])^[P.X] <> 0 then
               begin
                   PByteArray(B.ScanLine[P.Y-D.Y])^[P.X-D.X] := $FF;
                   Break;
               end;
           end;
       end;

       Canvas.Draw(0, 0, B);
   finally
       FreeAndNil(B);
   end;

end;</lang>

PureBasic

<lang PureBasic>#Window1 = 0

1. Image1 = 0
2. ImgGadget = 0

1. NUM_PARTICLES = 3000
2. width = 200
3. height = 200
4. xmax = #width -3
5. ymax = #height -3

Define.i Event ,i ,x,y

If OpenWindow(#Window1, 0, 0, #width, #height, "Brownian Tree PureBasic Example", #PB_Window_SystemMenu )

  If CreateImage(#Image1, #width, #height)
     ImageGadget(#ImgGadget, 0, 0, #width, #height, ImageID(#Image1))
     StartDrawing(ImageOutput(#Image1))
     FrontColor($FFFFFF)
     Plot( Random(#xmax) , Random(#ymax ))
     StopDrawing()
     SetGadgetState(#ImgGadget, ImageID(#Image1))
     For i = 1 To #NUM_PARTICLES
         x = Random(#xmax)+1 : y = Random (#ymax)+1
         StartDrawing(ImageOutput(#Image1))
         While Point(x+1, y+1) + Point(x, y+1)+Point(x+1, y)+Point(x-1, y-1)+Point(x-1, y)+Point(x, y-1) = 0
             x = x + (Random(2)-1) : y = y + (Random(2)-1) 
             If x < 1 Or x > #xmax Or y < 1 Or y > #ymax
                 x = Random(#xmax)+1 : y = Random (#ymax)+1
             EndIf   
         Wend
         Plot(x,y) 
         StopDrawing()
         SetGadgetState(#ImgGadget, ImageID(#Image1))          
     Next
     
  EndIf

   Repeat
     Event = WaitWindowEvent()
   Until Event = #PB_Event_CloseWindow

EndIf</lang>

Ruby

Library: RMagick

<lang ruby>require 'rubygems' require 'RMagick'

NUM_PARTICLES = 1000 SIZE = 800

def draw_brownian_tree world

 # set the seed
 world[rand SIZE][rand SIZE] = 1

 NUM_PARTICLES.times do
   # set particle's position
   px = rand SIZE
   py = rand SIZE

   hit = false
   until hit
     # randomly choose a direction
     dx = rand(3) - 1
     dy = rand(3) - 1

     if dx + px < 0 or dx + px >= SIZE or dy + py < 0 or dy + py >= SIZE
       # plop the particle into some other random location
       px = rand SIZE
       py = rand SIZE
     elsif world[py + dy][px + dx] != 0
       # bumped into something
       hit = true
       world[py][px] = 1
     else
       py += dy
       px += dx
     end
   end
 end

end

world = Array.new(SIZE) { Array.new(SIZE, 0) } srand Time.now.to_i

draw_brownian_tree world

img = Magick::Image.new(SIZE, SIZE) do

 self.background_color = "black"

end

draw = Magick::Draw.new draw.fill "white"

world.each_with_index do |row, y|

 row.each_with_index do |colour, x|
   draw.point x, y if colour != 0
 end

end

draw.draw img img.write "brownian_tree.bmp"</lang>