1. A computer-implemented method of facilitating animation of a scene comprising a plurality of objects, the plurality of objects represented by a plurality of models, the method comprising: receiving information identifying a first model to be animated from the plurality of models; using a first representation to determine a set of models from the plurality of models that are needed for evaluation of the first model, the first representation comprising information identifying one or more inputs and outputs of the models in the plurality of models and identifying dependencies between the one or more inputs and outputs; and loading the first model and the set of models in computer memory, wherein the plurality of models comprises at least one model that is not loaded into the computer memory.