import java.awt.Color;

class DLA {
	public static void main(String[] args) {
		//create the collision-check area
		int[][] field = new int[700][700];

		//calculate limits for coordinates from field
		int maxX = field[0].length-1;
		int maxY = field.length-1;
		
		//create and prepare drawing window
		Pad drawPad = new Pad();
		drawPad.setBackground(Pad.black);
		drawPad.setPadSize(maxX, maxY);
		drawPad.setVisible(true);
		drawPad.setColor(Pad.white);
				
		
		//set the first spot in the center
		setPixel(drawPad, field, maxX/2, maxY/2, Pad.white);
		
		int maxR=0;
		int count=0;
		while(maxR*2<maxX && maxR*2<maxY) {
			
			//spawn a pixel on a circle around the center
			double x = Math.toRadians(Math.random()*360);
			int movingPixelX = limit((int)(Math.cos(x)*(maxR+50))+maxX/2, 0, maxX);
			int movingPixelY = limit((int)(Math.sin(x)*(maxR+50))+maxY/2, 0, maxY);
			//Terminal.println("x: " + movingPixelX + " y: " + movingPixelY);
			
			//move the pixel until it moves to far out or touches the tree
			while(!isTouching(field, movingPixelX, movingPixelY)
				&& inRange(movingPixelX, movingPixelY, maxR+70, maxX, maxY))
			{				
				movingPixelX = moveRandom(movingPixelX);
				movingPixelY = moveRandom(movingPixelY);
			}
			
			
			if(isTouching(field, movingPixelX, movingPixelY)) {
				//some cool color calculation stuff
				int k = limit(255-(int)(255*((double)maxR*2)/(double)maxX), 0, 255);
				Color c = new Color(k, k, 255);
				
				//draw the new particle
				setPixel(drawPad, field, movingPixelX, movingPixelY, c);
				count++;
				Terminal.println("count: " + count);
				//update maxR if the new pixel has a bigger radius
				maxR = Math.max(maxR, (int)Math.hypot(movingPixelX-maxX/2, movingPixelY-maxY/2));
				
				//Terminal.println("maxR: " + maxR);
			}
		}
		
		
		return;
	}
	
	public static boolean inRange(int x, int y, int maxR, int maxX, int maxY) {
		//rpow2 is the radius r of the pixel to the power of 2
		int rpow2 = (maxX/2-x)*(maxX/2-x) + (maxY/2-y)*(maxY/2-y);
		
		//compare rpow2 with maxR^2, so we can compare radius without having to calculate a square root (performance)
		if(rpow2 < maxR*maxR)return true;
		else return false;
	}
	
	public static boolean isTouching(int[][] field, int x, int y) {
		
		//center
		if(testPixel(field, x  , y  ))return true;
		//up
		if(testPixel(field, x  , y-1))return true;
		//up-right
		if(testPixel(field, x+1, y-1))return true;
		//right
		if(testPixel(field, x+1, y  ))return true;
		//down-right
		if(testPixel(field, x+1, y+1))return true;
		//down
		if(testPixel(field, x  , y+1))return true;
		//down-left
		if(testPixel(field, x-1, y+1))return true;
		//left
		if(testPixel(field, x-1, y  ))return true;
		//up-left
		if(testPixel(field, x-1, y-1))return true;
		
		return false;
	}
	
	public static boolean testPixel(int[][]field, int x, int y) {
		int testX = 0;
		int testY = 0;
		int maxX = field[0].length-1;
		int maxY = field.length-1;
		
		testX = limit(x, 0, maxX);
		testY = limit(y, 0, maxY);
		if(field[testY][testX]>0)return true;
		else return false;
	}
	
	public static int limit(int value, int lower, int upper) {
		if(value<lower){value=lower;}
		if(value>upper){value=upper;}
		return value;
	}
	
	public static int moveRandom(int movePixel) {
		double r = Math.random();
		
		if(r<0.333) {return movePixel+1;}
		else if(r<0.666) {return movePixel-1;}
		else {return movePixel;}
	}
	
	public static void setPixel(Pad drawPad, int[][]field, int x, int y, Color c) {
		int maxX = field[0].length-1;
		int maxY = field.length-1;
		
		x = limit(x, 0, maxX);
		y = limit(y, 0, maxY);		
		
		field[y][x] = 1;
				
		drawPad.setColor(c);		
		drawPad.drawDot(x, y);
	}
	
}