C++ Objects::PDF方法代码示例

// only light sampling..
// left only for reference
inline void EstimateDirectIllumination (
	const Scene * thisScene,
	const Intersection * intersectionInfo,
	const Ray & ray,
	double & light_pdf,
	Spectrum & lightSourceSamplingContribution
)
{
	Objects * obj = intersectionInfo->object;
	BRDFModels * brdf = obj->brdf_model;

	Vector newRayDirection;
	Vector normalDirection;

	normalDirection = intersectionInfo->normal;

	Attenuation attenuationFactor;
	bool delta_brdf_hitEmissive = false;
	bool occludedByObjects = true;

	Spectrum lightIntensity;

	light_pdf = 0; // to be added

	if ( brdf->surfaceFlag == surface_delta )
	{
		return;
	}

	//		Spectrum lightSourceSamplingContribution;
	//		Spectrum brdfSamplingContribution;

	// light source sampling evaluation
	Objects * light;
	light = thisScene->AquireOneOfEmissiveObjects();

	Pnt3D pointOnLight;
	int i = 0;
	while ( i < 2 && occludedByObjects == true )
	{
		pointOnLight = light->samplePointOnObject();
		occludedByObjects = thisScene->Occluded(
			intersectionInfo->intersectionPoint,
			pointOnLight,
			light
		);

		i++;
	}


	if ( occludedByObjects == false )
	{
		newRayDirection = Normalize( pointOnLight - intersectionInfo->intersectionPoint );

		brdf->BRDF(
			ray.direction,
			newRayDirection,
			attenuationFactor
		);

		attenuationFactor.Scaled_by_Spectrum_Value( obj->material_type->color );

		// light pdf in angular form
		// should be returned for MIS
		light_pdf = light->PDF_in_solid_angle ( pointOnLight, intersectionInfo->intersectionPoint, newRayDirection );

		// not sure !!!
		double pointSamplePdf = light->PDF();

		Ray nextRay( intersectionInfo->intersectionPoint, newRayDirection );

		Vector normal_on_light;
		light->getNormalDirection( pointOnLight, normal_on_light );
		double geometryTerm = GeometricTerm( nextRay, normalDirection, pointOnLight, normal_on_light );

		lightIntensity = light->emission;
		lightSourceSamplingContribution = Attenuate_Light_Spectrum(
			attenuationFactor,
			lightIntensity
		) * geometryTerm / pointSamplePdf;
	}
	else
	{
		if ( DebugMode )
		{
			printf( "Direct illimination can not sample a point on light source" );
		}
	}
}