Maya Blobbies

The movies below show my attempt to simulate snow using Maya's particle systems. The particle type was set to blobby surfaces so that they would blend together when a certain threshold was reached.

Unfortunately my attempt to simulate the same effect seen above onto a character in motion was less successful. The blobs collide and stop with the character's mesh fine, but since the character is in motion, the force is translated back to the particle, and the character shrugs the blobs off. A solution would be to turn the character mesh into a goal object and animate its influence. Doing this causes the blobs to be attracted to the character like a magnet so the effect is unrealistic as seen to the left. Another problem was that I couldn't control where the particles would be attracted to on the mesh. I tried to write an expression so that the goal object is taken into account only when a blob collides with the surface, but after several tries, I couldn't get a realistic effect. I discovered that it is possible to assign a specific particle to a designated vertex, but the solution is tedious and lacks flexibility. An expression is still probably the best bet.

So what would be the next step if I got the particles to flutter down and stick correctly? After baking out the positions of the particles using a MEL script, I could substitute each particle with a renderman blobby. The advantage to this method is that I would be able to cause the blobbies to slowly slide down the character, blob together, and then fall to the ground as if the snow were melting and sloshing together.

Renderman Blobbies

This page follows the development of MEL and TCL scripts that use vertex detection and file manipulation techniques to create a character consisting of renderman blobby objects.

After modeling and animating a polygonal object, I wrote a MEL script that analyzes the mesh for each frame and then creates a text file consisting of three columns of XYZ coordinates representing each of the verticies. An example of the vertex text file can be found here.

After the text files have been created. A TCL script was used to read in the information and write out archived rib files with the correct blob syntax. Now the character animation can be rendered out with blobbies.

The final step was to create a simple proxy object in Maya that would represent the figure. When rendered, the proxy object was replaced by the appropriate .rib file with a glass shader. The example to the left was an attempt to grow the man out of a puddle. The effect is pretty weak and still needs some work, but the potential is there. Since there were many layers of blobbies at times, render times were much longer than I had anticipated. A raytracing reflection and refraction depth of 7 was used, but the dark areas imply the value still wasn't high enough.