A method, apparatus, and article of manufacture provide the ability to process image data. A data structure includes a plurality of nodes that represent processing to be performed upon image data. At least one node is generated as a three-dimensional object within a compositing space having a; least one light source. A viewport is defined in a space configured with a frustum enclosing the 3D object. A matte of the object is generated in relation to the light source within the space. The matte is accumulated in an accumulating shadow texture and the object is rendered including the accumulating shadow texture in an image frame defined by the frustum.