This is a tree rig I created in 2006 to add to a graphics demo at Whatif Productions.

The tree's palm fronds wave as if they were affected by a soft tropical breeze. The animation needed to use bones to be performance-friendly, and it needed to loop endlessly. I wanted to use a Wave spacewarp in 3ds Max to move the bones, but bones can't be affected directly by spacewarps.

Instead I deformed a helper mesh (the blue triangles) with a wave spacewarp (the pink grid), then assigned the tree bones to a simple IK system bound to the helper mesh. The bones align themselves with the end effectors but don't change their own length, so the fronds don't stretch or compress as the triangles move away from them... they simply wave around in the breeze.

I wanted more bounce on the fronds so I added two Noise spacewarps (the pink boxes); these gave the fronds some more organic motion. The noises cross-fade with each other to perform a proper loop... one is animated from 0 to 100% strength, the other from 100% to 0. Both also move their phases in the same positive direction. The phase for the first goes from -1 to 0, the other from 0 to 1. This way they fade to and from the same phase value at the loop point.



The fronds use a simpler more performance-friendly variation of the trick I used for the light-scattering effect. For the bottoms of the fronds I duplicated the upper faces, flipped their normals, and mapped them to the darker leaf texture.