The animation and notes on this page explain how custom shaders written in the RenderMan Shading Language can be animated using SLIM parameter expressions.

Final image is a composite of Maya playblast wireframes and rendered images. All the animation shown here is dynamics except for the stretch and squash.

After setting up a regular 3d bouncing ball simulation I copied the baked animation to the sliders that control the shader animation. One adjustment to the baked keys was to reverse the y axis since renderman t axis is inverse.

[mattr “pCube1._parameter_” f$] tcl expression was used to feed the Maya animation data to RenderMan shader variables.

It is possible to control the color of the surface, the ball, and the line, the position of the ball and the line, the size of the ball in terms of its radius, squash and stretch, and the line in terms of its thickness.

Even though the shader isn’t complex, it is still having trouble with image maps and causing maya and RAT not to respond, occasionally. Couldn’t figure out why...

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