Paint Change Transition

[Pearl]

I was inspired by the Scion car commercial that was shown in the Embassy Siggraph event a week ago. In it, the car changes color by flipping off its paint. It was really amazing and I wanted to try to re-create it in Houdini.

Sadly... it was harder than I thought.

So far, I can get the flipping to work on surfaces with semi-uniform normals and up vectors. i.e. Tubes, grids, and toruses. I'm having a lot of trouble with spheres. And, if I can't get it to work on a sphere, getting it to work on a car would be getting ahead of myself.

I posted my problem with spheres here:

http://odforce.net/forum/index.php?showtopic=4111

I started with calculating normals and rotating using Primitive on them. This turned out to be mathematically heavy, so I went onto idea #2.

Here's the result of idea #2:

http://www.pearlhsu.net/videos/pearlhsu-tubeChange1.mov

I used POPs to do this. Because the Rotate POP only likes to rotate correctly on the Z-axis, I had to first rotate each primitive to its side, and then post-rotate it back. This is why spheres don't work. The polygons on the sphere all rotate on different axis, so they don't line up in order for the Rotate POP to work.

Onto idea #3:

http://www.pearlhsu.net/videos/pearlhsu-torusChange1.mov

This was done using the roll option in the Sweep SOP, and stamping it. It's very convenient, but I'd have to figure out how to model a car using the Sweep SOP.

....

I'm going to keep trying different options. The POP method seems the most promising, but I'm still at a dead end.

I hope you guys like what I have so far.

Any suggestions are totally welcome!