Method begin

src/IECoreImage/LensDistortOp.cpp:103–168

}

void LensDistortOp::begin( const CompoundObject * operands )
{
	// Get the lens model parameters.
	IECore::CompoundObjectPtr lensModelParams( runTimeCast<CompoundObject>( lensParameter()->getValue() ) );

	// Load the lens object.
	m_lensModel = LensModel::create( lensModelParams );
	m_lensModel->validate();

	// Get the distortion mode.
	m_mode = m_modeParameter->getNumericValue();

	// Get our image information.
	assert( runTimeCast< ImagePrimitive >(inputParameter()->getValue()) );
	ImagePrimitive *inputImage = static_cast<ImagePrimitive *>( inputParameter()->getValue() );

	Imath::Box2i dataWindow( inputImage->getDataWindow() );
	Imath::Box2i displayWindow( inputImage->getDisplayWindow() );
	double displayWH[2] = { static_cast<double>( displayWindow.size().x + 1 ), static_cast<double>( displayWindow.size().y + 1 ) };
	double displayOrigin[2] = { static_cast<double>( displayWindow.min[0] ), static_cast<double>( displayWindow.min[1] ) };

	// Get the distorted window.
	// As the LensModel::bounds() method requires that the display window has it's origin at (0,0) in the bottom left of the image and the ImagePrimitive has it's origin in the top left,
	// convert to the correct image space and offset if by the display window's origin if it is non-zero.
	Imath::Box2i distortionSpaceBox(
		Imath::V2i( dataWindow.min[0] - displayWindow.min[0], displayWindow.size().y - ( dataWindow.max[1] - displayWindow.min[1] ) ),
		Imath::V2i( dataWindow.max[0] - displayWindow.min[0], displayWindow.size().y - ( dataWindow.min[1] - displayWindow.min[1] ) )
	);

	// Calculate the distorted data window.
	Imath::Box2i distortedWindow = m_lensModel->bounds( m_mode, distortionSpaceBox, ( displayWindow.size().x + 1 ), ( displayWindow.size().y + 1 ) );

	// Convert the distorted data window back to the same image space as ImagePrimitive.
	m_distortedDataWindow =  Imath::Box2i(
		Imath::V2i( distortedWindow.min[0] + displayWindow.min[0], ( displayWindow.size().y - distortedWindow.max[1] ) + displayWindow.min[1] ),
		Imath::V2i( distortedWindow.max[0] + displayWindow.min[0], ( displayWindow.size().y - distortedWindow.min[1] ) + displayWindow.min[1] )
	);

	// Compute a 2D cache of the warped points for use in the warp() method.
	IECore::FloatVectorDataPtr cachePtr = new IECore::FloatVectorData;
	std::vector<float> &cache( cachePtr->writable() );
	cache.resize( ( m_distortedDataWindow.size().x + 1 ) * ( m_distortedDataWindow.size().y + 1 ) * 2 ); // We interleave the X and Y vector components within the cache.

	for( int y = distortedWindow.max.y, pixelIndex = 0; y >= distortedWindow.min.y; --y )
	{
		for( int x = distortedWindow.min.x; x <= distortedWindow.max.x; ++x )
		{
			// Convert to UV space with the origin in the bottom left.
			Imath::V2f p( Imath::V2f( x, y ) );
			Imath::V2d uv( p[0] / displayWH[0], p[1] / displayWH[1] );

			// Get the distorted uv coordinate.
			Imath::V2d duv( m_mode == kDistort ? m_lensModel->distort( uv ) : m_lensModel->undistort( uv ) );

			// Transform it to image space.
			p = Imath::V2f(
				duv[0] * displayWH[0] + displayOrigin[0], ( ( displayWH[1] - 1. ) - ( duv[1] * displayWH[1] ) ) + displayOrigin[1]
			);