This weeks homework refers to soft bodies and springs. Soft bodies allow particles to manipulate and deform geometry. The particles drive the surface deformation through the vertices, but where ever the particles are, the geometry follows.
This week’s homework required an animated character to walk across three different types of simulated textures. One was rock (which I interpreted as solid rock and therefore would not perform any action), sand and mud.
This was done by applying soft bodies to a poly plane with a subdivision high enough for the plane to deform properly. I made sure that the soft bodies options were set to “Duplicate, make original soft” and that the goal weight was set to 0.5. I added a turbulence field to the plane to test if it deformed properly. Once I was satisfied with how the plane deformed, I deleted the field, selected the particles and created a string which I called grounds. I brought its stiffness up to 20 .
Next was the tricky part. I set the particles within the rock section of the surface to a goal weight of 1 so they would be unaffected by the deformation. I set the sand goal weights to 0.3, and the mud goal weight to the same value as the sand. However, I pulled the plane slightly up in the mud section so that it would have a larger effect on the collision of the animated character’s feet against the plane. This seem to respond well as the mud section appeared more blobby and mud like, while the sand would deform but slowly form back to its original state when the character walked by.
There was one last problem to be solved. The character especially in the mud section, would drag the plane along with it at certain points. This was due to the character’s feet moving bellow the plane at points. I solved this concern by moving the vertices of the feet up where ever they would pass under the plane. The surface still slightly moved with the character, but this is to simulate mud, which at points would stick to the feet. The final result was something I was overly happy with, but would still need at bit of work to get it completely right.