#version 130

void main(void)
{
	gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
	int depth = int(gl_Position.z);
	if (depth > 10000 || depth < 800) {
		depth = 0;
	}

	int y = depth % 256;
	int u = depth / 256;

	int C = y - 16;
	int D = u - 128;
	int E = -128;

	int r = (298 * C + 409 * E + 128) / 256;
	int g = (298 * C - 100 * D - 208 * E + 128) / 256;
	int b = (298 * C + 515 * D + 128) / 256;

	if (r < 0) { r = 0; }
	if (g < 0) { g = 0; }
	if (b < 0) { b = 0; }	

	if (r > 255) { r = 255; }
	if (g > 255) { g = 255; }
	if (b > 255) { b = 255; }	

	float fRed = float(r) / 256;
	float fGreen = float(g) / 256;
	float fBlue = float(b) / 256;
	gl_FrontColor = vec4(fRed, fGreen, fBlue, 1.0);
}