import cubemap_effect;
import _pbr_prefilter;

#pragma MSP stage(fragment)
layout(location=0) out vec3 frag_color;
void main()
{
	vec3 normal = normalize(texcoord);
	vec3 tangent = normalize(abs(normal.x)>abs(normal.y) ? vec3(-normal.z, 0.0, normal.x) : vec3(0.0, -normal.z, normal.y));
	mat3 orientation = mat3(tangent, cross(normal, tangent), normal);

	vec3 sum = vec3(0.0);
	float weight = 0.0;
	for(int i=0; i<n_samples; ++i)
	{
		vec3 halfway = orientation*ndist_ggxtr_importance_sample(hammersley(i, n_samples), roughness);
		vec3 light_dir = reflect(-normal, halfway);

		float n_dot_light = dot(normal, light_dir);

		if(n_dot_light>0)
		{
			sum += textureLod(environment_map, light_dir, 0).rgb*n_dot_light;
			weight += n_dot_light;
		}
	}

	frag_color = sum/weight;
}