hi.. Grain sim again.. i have a complex animated static collision object, and with the uniform divisions turned up sufficiently high, it takes a good percentage of my sim time “calculating SDF”

so i thought it would be a good idea to cache out the collision volume.

following info i found around here, i set the file mode in the static object DOP to “write” and set it to output “collision.$f4.simdata”

i then played throught the timeline, with a very low resolution (big particle separation|) grain sim,.

this gave me a folder full of 22 meg simdata files.

i then set the file mode in the static object DOP to “read” and pointed it to those files.

id assume that would be all i have to do?

however when i sim, it -still- spends ages “calculating SDF” and doesnt seem any faster than previously.

what did i miss?

thanks, Robin.

on a related note, i get many, many times faster performance when i turn off “volumetric collisions” (even with a cached sdf, as mentioned that doesnt seem to help)

however without volumetric collisions enabled, the particles explode all over the place, when they are hit by the collision object.

so i thought it would be a good idea to cache out the collision volume.

It is but you should do this at the SOP level not in dops. Just turn the geo into a low res volume and write out as .bgeo.sc

Rob

could you elaborate on why this is the case, and possibly some pointers on how to do it? it all seemed so logical and straightforward.

Why> Dops is for simulation, anything you do there will require running out the simulation. In sops this is not the case. So write out the geometry acting as a collision proxy volume. Doing this your optimizing your DOP sim.

How > Turn your geometry into a vdb volume > feed into DOps select the path to the proxy volume.

Rob