Author: admin

Archived post by JeffLMnT

“` How to deal with Iterations: Substeps – More expensive, but gives a better solve – especially for higher stiffness values Constraint Iterations – Increase for higher stiffness value to control excessive deformations – great for cheaper solver at high resolutions Smoothing Iterations –  smoothing ops, to smooth out errors of excessive deformations, or constraint errors Collision Iterations – Uses the Detangle sop – lower frequency iterations – complicated and time consuming – increase when collisions are fighting against constraints or other collisions However, its probably better to increase substeps and decrease constraint iterations for a more accurate solve – and to reduce load on the constraints – but is more expensive “`

Archived post by Bender

From @trzanko ray sop or prim uv’s don’t yield super great accuracy, as it only interpolates among a primitive’s points, to get a smooth position you can leverage the osd vex functions
here’s my subdiv ray snippet which illustrates this, you can see the diff between the osd pos and the primuv pos if you comment out the line which declares the variable sDP
“`int primNum; vector UV;
float dist = xyzdist( 1, @P, primNum, UV);
vector restN = primuv(1,”N”,primNum,UV); vector posOnRest = primuv(1,”P”,primNum,UV);
//subdiv float pU, pV; int pId; int patch = osd_lookuppatch( 1, primNum, UV.x, UV.y, pId, pU, pV);
//these two functions return the last argument //so posOnRest is being overwritten in the function, much like xyzdist() int sDN = osd_limitsurface( 1, ‘N’, pId, pU, pV, restN); int sDP = osd_limitsurface( 1, ‘P’, pId, pU, pV, posOnRest);
@P = posOnRest;“`

posting Tighe’s post for re-gemming

Archived post by Sasa Budimir

Little trick for those nasty gaps and weird sim behavior in vellum when using attach to geometry constraints. Say you have some vellum sim and want to attach few lines/hairs to it in the second sim (using the first one as collision). There is always a small gap between attached points, and after some time I figured it was due to collisions between those points that is forcing them apart, and causing some weird motion. Easy fix is to just disable collisions on those points that are going to be attached with: `i@disableexternal = 1;` Little GIF that hopefully illustrates things better (or not).

Attachments in this post:
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20192910/24/19/disable_collision_vellum.gif

Archived post by SniperJake945

if you’re too lazy to search 😛

this is that shit but on surfaces. I cant release the code for this unfortunately but it works on most if not all non degenerate triangle meshes 😮 the tracing methods are based off that keenan paper i posted in cgi-math about intrinsic triangulations 😮

will pump out some longer versions laterrr

gotta actually do work at some point today 😦

but if u dont want to do crazy surface tracing, you can just fake it with xyz dist and primuv, though itll be pretty slow for big meshes like this (100k points)

Attachments in this post:
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20190510/22/19/jr_physarum_revisited_reupload.hipnc
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20190510/22/19/jr_surface_physarum_v001.mp4