RT_GPU/shaders/scatter.glsl

Ray lambertRay(hitInfo hit, Ray ray, GPUMaterial mat, uint rng_state)
{
	vec3 diffuse_dir = normalize(hit.normal + randomDirection(rng_state));
	vec3 specular_dir = reflect(ray.direction, hit.normal);

	bool is_specular = (mat.metallic >= randomValue(rng_state));

	ray.origin = hit.position + hit.normal * 0.001;
	ray.direction = mix(diffuse_dir, specular_dir, mat.roughness * float(is_specular));

	return (ray);
}

// Ray dieletricRay(hitInfo hit, Ray ray, GPUMaterial mat)
// {
//     float	refraction_ratio;
// 	vec3	unit_direction;

//     refraction_ratio = 1.0f / mat.roughness;  //mat.roughness = refraction (saving memory)

// 	if (dot(ray.direction, hit.normal) > 0.0f)
// 	{
// 		hit.normal = -hit.normal;
// 		refraction_ratio = mat.roughness;
// 	}

// 	unit_direction = normalize(ray.direction);
// 	ray.origin = hit.position + hit.normal * -0.0001f;
// 	ray.direction = refract(unit_direction, hit.normal, refraction_ratio);
	
//     return (ray);
// }

Ray dieletricRay(hitInfo hit, Ray ray, GPUMaterial mat)
{
    float	refraction_ratio;
	vec3	unit_direction;

    refraction_ratio = 1.0f / mat.roughness;  //mat.roughness = refraction (saving memory)

    float d = dot(ray.direction, hit.normal);
    hit.normal *= sign(d);

	if (d > 0.0f)
		refraction_ratio = mat.roughness;

	unit_direction = normalize(ray.direction);
	ray.origin = hit.position + hit.normal * 0.0001f;
	ray.direction = refract(unit_direction, -hit.normal, refraction_ratio);
	
    return (ray);
}

Ray newRay(hitInfo hit, Ray ray, uint rng_state)
{
    GPUObject	obj;
	GPUMaterial	mat;

	obj = objects[hit.obj_index];
	mat = materials[obj.mat_index];

    if (mat.type == 0)
        return (lambertRay(hit, ray, mat, rng_state));
    else if (mat.type == 1)
        return (dieletricRay(hit, ray, mat));
    return (ray);
}