Abstract: User-defined interpolation modules can be associated with animation variables in an animation system. Interpolation modules determine the values of animation variables at a given time. Interpolation modules can perform any arbitrary type of calculation, evaluation, simulation, or other data manipulation using the knots of one or more animation variables and/or other data to determine the value of one or more animation variables at the desired evaluation time. Interpolation modules can preserve their current state and retrieve previous states, enabling the use data from previous executions of the interpolation module to determine the current values of animation variables. Interpolation modules can be written in any programming or scripting language and can be dynamically loaded by the animation system as needed. The interpolation module can define any arbitrary relationship between animation variables. Interpolation modules can add knots to an animation variable at any arbitrary time.

Abstract: In a computer aided animation system where an animation spline is produced from a sequence of knots, the display of the animation spline is modified so that the vertical axis of the curve is flipped at selected ‘pose’ knots in order to allow ready evaluation, typically by visual inspection, of the perception effect of the spline.