One embodiment of the present invention sets forth a technique rendering an image pixel within a graphics image with multiple shaders in a single rendering phase using a modular shader architecture. A user specifies how geometric objects, light sources, and various types of rendering operations in a graphics scene are associated. A rendering application provides computational infrastructure for rendering operations that includes finding an intersected object for each pixel of a target graphics image. The modular shader architecture includes a means for efficiently developing and incorporating custom shader modules for use by the rendering application.