Agents walking on a moving terrain?

[catchyid]

Hi,

In a crowd simulation, I have agents "walking" on a moving terrain, the terrain is translating and rotating. In the crowdsolver I check "Enable Terrain Projection" and point to the terrain, but this does not work - to be more specific, this only projects agents on the terrain so they don't fly, but any terrain horizontal motion won't affect the agents and they would slide/penetrate the terrain if it moves or rotates. 

Is there any built-in feature in Houdini that handles this situation? If not, then I guess I could project the agents on the terrain the first time they are spawned, and then on each iteration I adjust the agents motion to accommodate for the terrain motion (e.g. compute terrain delta v or delta p and apply them on agents...)

Thanks,

[cwhite]

There isn't currently anything built into the crowd solver for this, but you're thinking along the right lines. I would use a pair of SOP solvers - at the end of the timestep, use a Ray SOP in minimum distance mode and record the primitive number and uv coordinates, and then at the start of the next timestep use the Attribute Interpolate SOP to move the agents to their new position.

[catchyid]

Thanks cwhite   As per using Ray/Interpolate SOPs, where in the dop network I have access to per-solve or post-solve events? I could not find any similar stubs for these events in the "crowd solver" and "multi-solver" nodes? 

Thanks alot...

[cwhite]

If you have the crowd solver wired into a multisolver, you can wire in SOP solvers before and after the crowd solver to perform pre-solve or post-solve work