I'm trying to get a density ramp on a volume and I'm having trouble understanding how volume sample works. I assume that it returns -1 to 0 when it's inside the volume and 0 to 1 outside. Somehow I'm not able to drive the density with the output. It just seems to affect a tiny portion of the edge and a giant chunk of the inside. What am I doing wrong? (I also tried a switch to only send a value to density when volume sample is between -1 and 0, plus a fit to switch it to 0 to 1 so that it's a usable density value, but still no luck.) See attached HIP file. Thank you!

Hi,

I assume you are using the @density directly in the chramp function, which would cycle the density value over 1 back to the beginning, i.e. keep only the fractional part over 1.0.

If you fit your density first, it will make sure to clamp them properly to 0-1 range:

animatrix_
If you fit your density first, it will make sure to clamp them properly to 0-1 range:

Thanks for the reply. I added the VEX you suggested and I'm still getting control only over the very edge of the sphere. I tried a few different inputs and ramp settings, as well as tweaking the VOP, but still no luck. I'm just having trouble visualizing what exactly volume sample is outputting. Is there a way to check on it? Geometry spreadsheet doesn't show the density values for each voxel.

Update! I switched out the cloud for a VDB from polygons. Same result, but then I checked "fill interior" and suddenly it's working. I have no idea what's going on.