[Sidefx-houdini-list] Motion blur on Volume Primitives?

Francois-Xavier Boussard b.fx at free.fr
Tue Feb 17 05:30:51 EST 2009


Hello,

You can use the name sop to create primitive name attributes that will contain the vel values. Each voxel will contain one named value as i understand it.

An example on a sphere to add a velocity in y axis:

You will need 4 name sops, one to create the density name, the three others to create vel.x vel.y vel.z, use the VolumeMix sop to modulate the values.
Create an isoOffsetVolume parented to a sphere, give it a good sampling value, create a name sop, give density as value for the Name parameter.
Create three more name sop parented to the isoOffsetVolume, give vel.x, vel.y, vel.z respectivly as value for the Name parameter.
Append volumeMix sop to the name sops output, set them to mix method 'user', multiply the $V value by the amount off velocity or density you need for testing.
Merge the density and the vel.

                        sphere(rad1)
                          |
             IsoOffsetVolume(Fog volume, uniformSmapling 50)
   |               |                |                    |
Name(density)   Name(vel.x)      Name(vel.y)          Name(vel.z)
   |               |                |                    |
   |           VolumeMix(User)  VolumeMix(User)      VolumeMix(User)
   |               |($V*0)          |($V*25)             |($V*0)
                                 Merge

this should give you a volume with density 1 and a velocity value of (0,25,0)
Apply the vex volume cloud shader for testing. Do not forget to enable the Object Velocity Blur from the render/sampling tab, obvious :)

This is reproducing the attributes you have out of the dops when using gas fluid. 
Cheers
francois



--- Mail Original -----
De: craigleehoffman at aol.com
À: sidefx-houdini-list at sidefx.com
Envoyé: Mardi 17 Février 2009 10:11:12 GMT +01:00 Amsterdam / Berlin / Berne / Rome / Stockholm / Vienne
Objet: [Sidefx-houdini-list] Motion blur on Volume Primitives?

Is this supported yet?? I have been reading docs and searching the forums and it seems like "no", but perhaps I am missing something.

I can make a Volume Primitive with the IsoOffset method, and I can get it to Motion Blur if I have animation at the OBJ level (or Transformation Blur), but I can't get it to Motion Blur using a Velocity Attribute, which is critical for what I am trying to do.? I understand this works for Metaballs and i3d files, but does it work for Volume Primitives?

Thanks,
Craig



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