stochastic ray tracing - adapt part

gistfile1.txt

var win = [ [],[],[],[],[] ];
var flags = [ [],[],[],[],[] ];
var winLength = 4;

function arand() {
	return Math.random()/4 - 1/8;
}

function adapt(x,y, i,j, step) {
	
	// i is for col
	// j is for row
	// win = [ 1row, 2row, 3row, 4row, 5row ]
	// 1row = [ 1col, 2col, 3col, 4col, 5col ]
	
	var xi,yj;
	var coord;
	
	console.log( 'step:',step );
	// left up corner
	if( !flags[j][i] ) {
		xi = x + i/winLength + arand();
		yj = y + j/winLength + arand();
		coord = '(x,y)'.replace( 'x', xi ).replace( 'y', yj );
		console.log( 'left up corner', coord );
		win[j][i] = coord
		flags[j][i] = true;
	}
	// right up corner
	if( !flags[j][i+step] ) {
		xi = x + (i+step)/winLength + arand();
		yj = y + j/winLength + arand();
		coord = '(x,y)'.replace( 'x', xi ).replace( 'y', yj );
		console.log( 'right up corner', coord );
		win[j][i+step] = coord
		flags[j][i+step] = true;
	}
	// left bottom corner
	if( !flags[j+step][i] ) {
		xi = x + i/winLength + arand();
		yj = y + (j+step)/winLength + arand();
		coord = '(x,y)'.replace( 'x', xi ).replace( 'y', yj );
		console.log( 'left bottom corner', coord );
		win[j+step][i] = coord
		flags[j+step][i] = true;
	}
	// right bottom corner
	if( !flags[j+step][i+step] ) {
		xi = x + (i+step)/winLength + arand();
		yj = y + (j+step)/winLength + arand();
		coord = '(x,y)'.replace( 'x', xi ).replace( 'y', yj );
		console.log( 'right bottom corner', coord );
		win[j+step][i+step] = coord
		flags[j+step][i+step] = true;
	}
	
	if( step === 1 )  {
		return;
	}
	
	step /= 2;
	step = ~~step;
	
	adapt( x,y, i,j, step );
	
	adapt( x,y, i+step,j, step );
	
	adapt( x,y, i,j+step, step );
	
	adapt( x,y, i+step,j+step, step );
	
}

adapt(0,0, 0,0, winLength );