help with creep

[rohandalvi]

hi,

I want to get particles to slide over a surface but in a turbulent fashion. My reference point is the god face from Matrix Revolutions. where all those tiny insect like robots move to create that baby's face, and then they keep on slide over it in streams.

I got most of it working but the creep sop is causing problems. I want the particles to move over the entire surface but currently they are limited to a certain part of my sphere.

Any help would be really appreciated. Also what do u do if you have a Polygonal object, since creep seems to work best with NURBS?

with regards

Rohan Dalvi

turbulence_creep.hipnc

[johner]

hi,

I want to get particles to slide over a surface but in a turbulent fashion. My reference point is the god face from Matrix Revolutions. where all those tiny insect like robots move to create that baby's face, and then they keep on slide over it in streams.

I got most of it working but the creep sop is causing problems. I want the particles to move over the entire surface but currently they are limited to a certain part of my sphere.

Any help would be really appreciated. Also what do u do if you have a Polygonal object, since creep seems to work best with NURBS?

with regards

Rohan Dalvi

Well, a really quick look shows that your VOP POP is not generating values for the Creep POP that span the 0-1 UV Range. To see this quickly, switch the second input to your POP net to a NURBs grid (you shouldn't need a UVProject or UVTexture with NURBs in this case) . Looking at it from above, you'll see the UV's you're passing into the Creep POP cluster around the middle. When that's mapped to a sphere, it's clumping in the regions you see.

The problem with switching your example to Polygons is you're not dealing with the "Primitive Number" parameter in the Creep POP. With a NURBs sphere as input, there's only one primitive, so your setting (prim number of 0) is fine. With a Polygon input, each triangle (or quad or whatever) is a primitive, so you have to deal with that parameter.

The bigger issue is it looks like you're trying to generate velocity in your VOP POP, but then just punt and plug those values directly into the UV of the Creep POP, which just means the particles are being snapped directly to those values, ignoring the velocity or any other forces. With a NURBs sphere that almost works since you can avoid the prim number problem. And if you can get those values to map the entire 0-1 range in a way you like you might be done. But if you're trying to have particles that stick to a polygonal sphere and obey forces you're going to have to set up the Creep POP with proper values at particle birth, then let it do its work as you apply forces to the particles themselves.

I put an example file in this topic that shows a way to set this up with a polygonal sphere.

Good luck