Color gradient on object?

[Andrew Morrison]

Is it possible to change the color of an object from one color to another on opposite sides of the object?  I'm trying to get a gradient of color going around a ring object as a function of the angle around the ring, but I am not sure if that is possible.  Thoughts?

Thanks!

Andrew

[Bruce Sherwood]

No, there isn't an easy way to do this. There is a missing feature in the extrusion object, a feature that was available in VPython 6, which is to specify an array of colors to be used for the segments of the extrusion.

However, you can use vertex and triangle or quad objects to make any arbitrary object, with any colors, though it's somewhat effortful.

Bruce

[Andrew Morrison]

Ah, bummer.  I whipped up a Doppler effect demo and one of the suggestions I got was to shade one side of the wavefronts blue and the other side red.  I thought it was an interesting suggestion, but then realized it wouldn't be easy to implement.  Just thought I would ask.

(here's the sim: https://trinket.io/library/trinkets/5e20b804da )

[Bruce Sherwood]

Now that I've seen your program I realize that being able to color the segments of an extrusion wouldn't help. A ring object is quite unusual. It requires its own special GPU processing because when you change its radius the thickness doesn't change. When you change a dimension of an extrusion object this affects all of the elements of the object.

Bruce

[Bruce Sherwood]

On second thought, use curve objects. You can specify colors along a curve. 

Bruce