The Sphere
The majority of the following text has been cut directly from my post on the trueSpace Forum. This covers the basic concept of the proposed Sun Catcher animation.
Modeling the Sphere:
When I first started making the sphere I actually thought I had it done fairly
simply and painlessly. My early ideas were to create a simple sphere primitive
and apply a corrosive texture to it. These are the settings I used:
Displacement: None
Reflectance: Glass
Shine: 0.95
Rough: 0.1
Mirror: 0
Trans: 0.91
Refract: 1.6
Transparency: Eroded
Scale: 0.1
Coverage: 0.5
Fuzz: 0
At this point I came across a slight problem: The actual rendered image looked fantastic and I had achieved exactly what I originally intended to do with only a few minutes of actual work. The problem was that light didn't actually seem to behave exactly as I had expected. The idea was that the sphere was to have a light source at its centre and the glassy bits of the sphere would create small shadows on the surfaces around it due to their slight opaqueness. No matter what transparency I used, the texture would not let any light through.
The model in both images is exactly the same only the shader attributes have changed, however the shadow definition remains the same for both images. This told me that with the corrosive transparency shader selected, shadow casting is adversly affected. No matter what changes I made to rendering options (Raytracing, Scanline, etc.), shader options (transparency, transfusion, diffusion, etc.), or shadow options (shadowmaps, etc.) I could not get past this problem.
At this point I posted a message to the trueSpace forum regarding my little dilemma and had a couple of suggestions though none actually seemed to fix it. Not all was lost, however, Binky put me onto the Dielectric Reflectance, which is the glass setting I eventually used. I love this shader!
After numerous days on this problem, I decided on another course of action. I would have to model the sphere cutting out irregular holes and applying the glass shader later. I did this by creating odd-shaped curvy 'things' and subtracting these from a hollowed spherical primitive. I eventually made about five 'master' odd-shaped curvy things of various sizes and shapes. All I did was pick one, copy it, rotate it, size it then subtract it from the sphere. Then I'd start all over again. Within about half an hour, I'd subtracted about seventy or eighty percent of the original sphere and was left with this:
I then copied the sphere twice and shrank both copies to a little smaller than the original so that I had three spheres - one inside another:
The idea was to animate these spheres rotating in different directions and at different speeds. The inner-most sphere would move the quickest in one direction, the middle sphere would move a little slower in another direction while the outer sphere would move in a third direction quite slowly. I hoped that this would create a rather spectacular effect. Time would tell.
Here is an animation of the original ‘corrosive textured’ sphere:
(200k, 1sec.)
Here is an animation of the final product using the method described above:
(270k, 2sec.)
The slightly yellow tinge to the animation is from the light source at the centre of the sphere and not the glass (which is based white).
The Sun Catcher animation tutorial:
The Work In Progress introduction post