Animate colorful, random paint drip art with SFML 1.6

paintDrip.cpp

#include <SFML/Graphics.hpp>
#include <vector>
#include <queue>
#include <cmath>
#include <iostream>
#include <ctime>
using namespace std;

const int width = 1366,
		  height = 768,
		  base = 250,
		  update = 1,
		  skip =8000;

// 4-direction update
const int dx[4] = {-1,0,0,1},
		  dy[4] = {0,-1,1,0};	

sf::Color color(100,128,255,255);

struct coor{
	coor(){
		x=0,y=0,v=0;
	}
	coor(int X,int Y,int V){
		x=X;
		y=Y;
		v=V;
	}
	int x,y,v;
};

int main(){
	srand(time(NULL));

	// Initialization
	sf::RenderWindow window(sf::VideoMode(width,height,32), "Test");

	sf::Image img;
	img.create(width,height,sf::Color::White);

	vector< vector<bool> > pix;
	pix.assign(width,vector<bool>(height,false));

	queue<coor> q;

	sf::Texture texture;
	texture.loadFromImage(img);
	sf::Sprite sprite;
	sprite.setTexture(texture);

	img.setPixel(width/2,height/2,color);
	pix[width/2][height/2] = true;
	q.push(coor(width/2,height/2,base));
	coor now;
	int nx,ny,nv;
	sf::Color newColor;

	sf::Clock clock;
	sf::Time elapsed = clock.getElapsedTime();

	// Main loop
	while(window.isOpen()){
		
		// Window close routine
		sf::Event event;
		while(window.pollEvent(event)){
			if ((event.type == sf::Event::Closed) ||
            	(event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Escape) )
                window.close();
		}

		elapsed = clock.getElapsedTime();
		if(elapsed.asMilliseconds() >= update){
			clock.restart();

			for(int u=0;u<skip;++u){

				if(q.empty()){
					color.r=rand()%255;
					color.g=rand()%255;
					color.b=rand()%255;
					nx=rand()%width,ny=rand()%height;
					//cerr<<nx<<' '<<ny<<'\n';
					pix.assign(width,vector<bool>(height,false));
					pix[nx][ny]=true;
					//cerr<<"here\n";
					newColor=img.getPixel(nx,ny);
					newColor.r=(newColor.r+color.r)/2;
					newColor.g=(newColor.g+color.g)/2;
					newColor.b=(newColor.b+color.b)/2;
					img.setPixel(nx,ny,newColor);
					q.push(coor(nx,ny,base));
				}

				now = q.front();
				q.pop();

				for(int i=0;i<4;++i){
					nx=now.x+dx[i];
					ny=now.y+dy[i];
					
					if(nx<0 || nx>=width || ny<0 || ny>=height || pix[nx][ny]) continue;
					if(rand()%base > now.v) continue;

					pix[nx][ny]=true;
					newColor=img.getPixel(nx,ny);
					newColor.r=(newColor.r+color.r)/2;
					newColor.g=(newColor.g+color.g)/2;
					newColor.b=(newColor.b+color.b)/2;
					img.setPixel(nx,ny,newColor);
					nv=now.v;
					nv+=rand()%7-4;
					nv=min(base,nv);
					q.push(coor(nx,ny,max(1,nv)));
					//cout<<now.v-1<<' '<<q.size()<<'\n';
				}

			}
		}

		texture.update(img);
		texture.setSmooth(true);
		window.clear(sf::Color::White);
		window.draw(sprite);
		window.display();
	}

}