Method imagePrimitive

src/IECoreGL/LuminanceTexture.cpp:159–214

}

IECoreImage::ImagePrimitivePtr LuminanceTexture::imagePrimitive() const
{
	ScopedBinding binding( *this );

	GLint width = 0;
	GLint height = 0;
	glGetTexLevelParameteriv( GL_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, &width );
	glGetTexLevelParameteriv( GL_TEXTURE_2D, 0, GL_TEXTURE_HEIGHT, &height );

	GLint aSize = 0;
	glGetTexLevelParameteriv( GL_TEXTURE_2D, 0, GL_TEXTURE_ALPHA_SIZE, &aSize );

	unsigned int numChannels = aSize ? 2 : 1;

	vector<float> data( width * height * numChannels );

	glGetTexImage( GL_TEXTURE_2D, 0, numChannels==2 ? GL_LUMINANCE_ALPHA : GL_LUMINANCE, GL_FLOAT, &data[0] );

	FloatVectorDataPtr yd = new FloatVectorData();
	vector<float> &y = yd->writable(); y.resize( width * height );

	FloatVectorDataPtr ad = nullptr;
	vector<float> *a = nullptr;
	if( aSize )
	{
		ad = new FloatVectorData();
		a = &ad->writable(); a->resize( width * height );
	}

	unsigned int i = 0;
	for( int yy=height-1; yy>=0; yy-- )
	{
		float *ry = &y[yy*width];
		float *ra = a ? &(*a)[yy*width] : nullptr;
		for( int x=0; x<width; x++ )
		{
			ry[x] = data[i++];
			if( ra )
			{
				ra[x] = data[i++];
			}
		}
	}

	Box2i imageExtents( V2i( 0, 0 ), V2i( width-1, height-1 ) );
	IECoreImage::ImagePrimitivePtr image = new IECoreImage::ImagePrimitive( imageExtents, imageExtents );
	image->channels["Y"] = yd;
	if( a )
	{
		image->channels["A"] = ad;
	}

	IECoreGL::Exception::throwIfError();

	return image;
}