1. A method for pre-computing ambient shadowing parameters for a computer-generated scene, the method comprising: retrieving a reference object associated with the computer-generated scene and comprising a plurality of vertices; for each vertex in the plurality of vertices: computing a local ambient shadowing parameter, and storing the local ambient shadowing parameter in a memory; and for each instance of the reference object included in the computer-generated scene: computing a first global ambient shadowing parameter for the instance based on the position of the instance within the computer-generated scene, and storing the first global ambient shadowing parameter in the memory.