#version 120

void main(void)
{
	gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
	
	float x = gl_Position.x;
	float y = gl_Position.y;
	float z = gl_Position.z;

	int depth = int(sqrt(x * x + y * y + z * z));

	if (depth < 800) {
		depth = 0;
	}

        if (depth > 10000) {
          depth = 10000;
        }

	float d = float(depth) / 10000.0;

	gl_FrontColor = vec4(d, d, d, 1.0);
}