Hi,

I'm trying to adapt the billowysmoke shader so that the ramp is based on an axis instead of density. Yet the results are strange as you can see on the picture. The ramp should go from red to blue like on the shader ramp but it doesn't happen, it looks like green and blue are compressed.

I tried changing the transform for current to world and other values, but it doesn't get better. I also tried adding normalize and fit nodes but couldn' t get the desired result.

I must be missing some magic node somewhere.
Help !

I guess you are applying the shader to a unit cube. The default unit cube is centered on the origin, so its Y-coordinates range from -0.5 to +0.5

Your ramp, on the other hand, goes from 0 to 1, so the bottom half of the cube gets the value at zero, while the top of the cube reaches half way into your ramp.

You could insert a Fit Range VOP to refit the extents of your volume into the 0…1 range expected by Range VOP.

Hi Eetu,

As I added a transform node to remap it to object space, Moving the cube around in Y axis didn't change the look of the ramp which is what I wanted.

Then I made more test, and found out that if I offseted the cube using an Xform in SOP so that it sits on the floor and has the correct offset in the other axes as well, the researched look was reached.

Now I can move the object using it's transform settings and keep the same look. Goal reached, thanks !

My confusion came from the fact that I thought that object space would be deeper in the SOP level, not at the transform level.

Thank you !