get center of Box in VOPs

[jon3de]

Hello,

Im working on some cloud pieces. In the attached picture you can see my current cloud "tile". I try to fade out the density on x and z axis to get a more radial shape. My plan is to calulate the distance from the center of the volume and multiply the density with it. The problem is the cloud tile is currently not centered at the origin. So I think I need the center of the volume instead of just the origin to calulate the distance properly. Of course I could manualy try to calulate the desired position and use that but i thought maybe there is a way to do that procedural in the vops network so it also does not break If I transform the volume after. Would be nice to get some help here. Thanks.

 

kind regards

Jon

 

 

cloudTile.hipnc

[goldleaf]

You can use relbbox() or the equivalent VOP, which gives you 0-1 position of each voxel in the local bounding box. Then wire that up to a Spline Ramp parm, multiply against density (or whatever your volume is), and adjust your ramp as desired.

 

 

 

[jon3de]

Thank you Chris I did not know the "relbbox" It´s much more practical than my "smooth" setup I created. Nevertheless it does not quite solves the problem with the desired round shape. If I look at the cloud from top view I try to get a more round shape than a box shape. (I should have explained that a little better) I think the distance of each voxel to the center wired up into  a spline ramp would give me what I want. hm...

[goldleaf]

Oops, I missed the rounded part! Just create a spline against the X and Z components of the Relative BBox Position, multiply those together with density, set both spline parms to look like this:

 

 

If linear interpolation isn't smooth enough, try one of the others (Catmull, Bezier...)