Alternate source for controlling an animation

A computer-readable medium storing computer-executable instructions for causing a computing device programmed thereby to perform a method comprising:

• providing a programming interface that facilitates binding of an input of an animation to a given source other than time, wherein the animation specifies variations in value of a property of the target object;
• and
• receiving a call to the programming interface;
• and
• returning from the call.

In a computing device that implements a rendering engine, a method comprising:

• with the computing device that implements the rendering engine, determining a first animation for a first target object that has a first target object property, wherein the first animation specifies variations in value of the first target object property, and wherein an animation input of the first animation is set to a given source other than time;
• with the computing device that implements the rendering engine, determining a second animation for a second target object that has a second target object property, wherein the second animation specifies variations in value of the second target object property, and wherein an animation input of the second animation is also set to the given source other than time;
• and
• with the computing device that implements the rendering engine, iteratively rendering the first target object and the second target object at runtime, including:
• evaluating the first animation based on value of the given source, including computing the value of the first target object property;
• and
• evaluating the second animation based on the value of the given source, including computing the value of the second target object property.