import postprocess;
import ambientocclusion;

#pragma MSP stage(fragment)
void main()
{
	vec3 center = unproject(vec3(vertex.xy, texture(depth, texcoord).r));
	vec2 tex_scale = 1.0/vec2(textureSize(occlusion, 0));
	float sum = 0.0;
	float count = 0.0;
	for(int i=0; i<4; ++i)
		for(int j=0; j<4; ++j)
		{
			vec2 offset = vec2(float(i), float(j))-1.5;
			vec2 sample_coord = texcoord+offset*tex_scale;
			float occ = texture(occlusion, sample_coord).r;
			float sample = texture(depth, sample_coord).r;
			float z_range = occlusion_radius*length(offset)*edge_depth_threshold;
			float min_depth = project(vec3(center.xy, center.z+z_range)).z;
			float max_depth = project(vec3(center.xy, center.z-z_range)).z;
			if(sample>=min_depth && sample<=max_depth)
			{
				sum += occ;
				count += 1.0;
			}
		}
	vec4 src_color = texture(source, texcoord);
	frag_color = vec4(src_color.rgb*mix(1.0, min(sum*2.0/count, 1.0), darkness), src_color.a);
}