Casting shadows of volumes, not in them.

[pinkwerks]

I've been playing with parti_volume and I can get shadows in my volumes but no correct shadows of them.

For example I have a sphere with transmat assigned to the material shader, and parti_volume (with some non-uniformity) to the the volume shader... I've got a spot light pointed at the ball (though it's not positioned in the volume) and I'm trying to cast a shadow on the wall that isn't a solid shape (I'd like to see the non-uniformity).

If someone has any insight I'd appreciate it. I'm writing my own volume shader and I'm wondering if it needs to double as a shadow shader - or should a shadow shader be calling the volume? I'm a bit confused.

[bart]

A volume shader will be used as a shadow shader when you have shadow segments on in the mental ray globals. Usually, then in the shader you detect for when you are being called as a shadow shader, and do something slightly different, like just occlusion calculation.

Shadow segments might be the default in Maya, but I'd check it.

[mattMR]

Hello,

The parti_volume works good with segmented shadows as Bart said, but work better with raytraced shadows... I tried with detailled shadows map or simple shadows map and the shadows in volume is good but not drop to the floor or wall. So use raytraced shadows for parti_volume. To optimise your render make 2 scenes, the color scene (all without fog) and the fog only (use "usebackgound" to get shadows from volume) or do all in one passes if you have time

Matt