__kernel void laplace(__global float * a, __global float * b, int size, int swap)
{
	size_t x, y;

	x = get_global_id(0);
	y = get_global_id(1);

	if (y > 0 && y < size - 1 && y > 0 && y < size - 1)
	{
		if (swap)
			a[x + size * y] = 0.25 * (b[(x-1) + size * (y)] + b[(x-1) + size * (y)] + b[(x) + size * (y-1)] + b[(x) + size * (y+1)]);
		else
			b[x + size * y] = 0.25 * (a[(x-1) + size * (y)] + a[(x-1) + size * (y)] + a[(x) + size * (y-1)] + a[(x) + size * (y+1)]);
	}
}