Method doOperation

src/IECoreImage/EnvMapSampler.cpp:109–189

}

ObjectPtr EnvMapSampler::doOperation( const CompoundObject * operands )
{
	ImagePrimitivePtr image = static_cast<ImagePrimitive *>( imageParameter()->getValue() )->copy();
	Box2i dataWindow = image->getDataWindow();

	// find the rgb channels
	ConstFloatVectorDataPtr redData = image->getChannel<float>( "R" );
	ConstFloatVectorDataPtr greenData = image->getChannel<float>( "G" );
	ConstFloatVectorDataPtr blueData = image->getChannel<float>( "B" );
	if( !(redData && greenData && blueData) )
	{
		throw Exception( "Image does not contain valid RGB float channels." );
	}
	const vector<float> &red = redData->readable();
	const vector<float> &green = greenData->readable();
	const vector<float> &blue = blueData->readable();

	// get a luminance channel
	LuminanceOpPtr luminanceOp = new LuminanceOp();
	luminanceOp->inputParameter()->setValue( image );
	luminanceOp->copyParameter()->getTypedValue() = false;
	luminanceOp->removeColorChannelsParameter()->getTypedValue() = false;
	luminanceOp->operate();

	// do the median cut thing to get some samples
	MedianCutSamplerPtr sampler = new MedianCutSampler;
	sampler->imageParameter()->setValue( image );
	sampler->subdivisionDepthParameter()->setNumericValue( subdivisionDepthParameter()->getNumericValue() );
	ConstCompoundObjectPtr samples = boost::static_pointer_cast<CompoundObject>( sampler->operate() );
	const vector<V2f> &centroids = boost::static_pointer_cast<V2fVectorData>( samples->members().find( "centroids" )->second )->readable();
	const vector<Box2i> &areas = boost::static_pointer_cast<Box2iVectorData>( samples->members().find( "areas" )->second )->readable();

	// get light directions and colors from the samples
	V3fVectorDataPtr directionsData = new V3fVectorData;
	Color3fVectorDataPtr colorsData = new Color3fVectorData;
	vector<V3f> &directions = directionsData->writable();
	vector<Color3f> &colors = colorsData->writable();

	float radiansPerPixel = M_PI / (dataWindow.size().y + 1);
	float angleAtTop = ( M_PI - radiansPerPixel ) / 2.0f;

	for( unsigned i=0; i<centroids.size(); i++ )
	{
		const Box2i &area = areas[i];
		Color3f color( 0 );
		for( int y=area.min.y; y<=area.max.y; y++ )
		{
			int yRel = y - dataWindow.min.y;

			float angle = angleAtTop - yRel * radiansPerPixel;
			float weight = cosf( angle );
			int index = (area.min.x - dataWindow.min.x) + (dataWindow.size().x + 1 ) * yRel;
			for( int x=area.min.x; x<=area.max.x; x++ )
			{
				color[0] += weight * red[index];
				color[1] += weight * green[index];
				color[2] += weight * blue[index];
				index++;