im doing a grain sim, and ive imported my animated collision object (a “plant” uncurling upwards from beneath (through) the floor collision object) as an alembic exported from 3dsmax.

ive set it as a static collision object with “use deforming geometry” enabled.


the sim runs until the first frame that the collsion object moves, then houdini crashes.

without that object in the simulation, it runs fast and fine.

ive tried with the default volumetric collisions (ray intersect) with various division levels. ive also tried with volumetric collisions disabled, and i get the same crash.

this crash is before the collision object has contacted any particles.


i also tried using the “deforming object” shelf tool instead of the static collision object.. same crash.

i dont know how tolerant houdini is of mesh quality? the mesh has some holes in (which i can try to close) , and when its in its fully curled up position there may well be some intersections in small details. .. however this is the mesh i have to work with.




the collision guide looks ok on the first frame. filling the object nicely apart from the smaller details. but im a complete noob so i dont know what to look for really.

so, is a “poor” mesh going to crash houdini? is there a way to do collisions with grains that is tolerant of such meshes? am i going to have to spend ages creating a new a mesh specifically for this collision?

id like to avoid this like the plague if possible.

id upload a file but the alembic is 1.6GB.

Hi,

Do some quick debugging , take a box sop and use it as a replacement for your 1.6 gig ! file > animate it . Then your determining if its a cause.

Plant model > to do correct collisions you do need a closed object > you could attempt to fix this in houdini with a group sop > group unshared edges > then fuse them , then write out the fixed geometry.

Rob

ok so i found an easy fix for the crashing. i just applied a “cap holes” modifier in max before exporting. seems the small gaps ( vents, its not exactly a plant) were causing the crash.

im surprised that houdinis reaction in this case is so graceless. ive found it generally pretty stable so far.