Aspects include API interfaces for interfacing shaders with other components and/or code modules that provide ray tracing functionality. For example, API calls may allow direct contribution of light energy to a buffer for an identified pixel, and allow emission of new rays for intersection testing alone or in bundles. The API also can provide a mechanism for associating arbitrary data with ray definition data defining a ray to be tested through a shader using the emit ray call. The arbitrary data is provided to a shader associated with an object that is identified subsequently as having been intersected by the ray. The data can include code, or a pointer to code, that can be used by or run after the shader. The data also can be propagated through a series of shaders, and associated with rays instantiated in each shader.