Brownian tree
This page uses content from Wikipedia. The original article was at Brownian_tree. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance) |
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.
- 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.
- Particles are injected into the field, and are individually given a (typically random) motion pattern.
- 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
<lang c>#include <string.h>
- include <stdlib.h>
- include <time.h>
- include <math.h>
- include <FreeImage.h>
- define NUM_PARTICLES 1000
- 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>
PureBasic
<lang PureBasic>#Window1 = 0
- Image1 = 0
- ImgGadget = 0
- NUM_PARTICLES = 3000
- width = 200
- height = 200
- xmax = #width -3
- 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
Ruby
<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>