Grain, sand, powder (vellum) in Houdini

Grain, sand, powder (vellum)

add some testgeo, which will become the grain body then add vellum configure grain node check click points from volume Grain size: 0.05 check jitter scale (to arrange more randomly) add vellum constraints node feed only first input add 2 null nodes name them geo, constraint feed in first 2 of vellum constraint node go up into /obj context add dopnet node cache tab -> cache memory: 25000 then dive inside dopnet node add vellum object node Initial Geometry: select geo null here Initial Constraint: select constraint null here add vellum solver node substep: 15 (to keep them together) Static Threshold: 1 advanced tab -> Attraction Weight: 1 (this defines how much it will clump) add gravity force node and connect to output (for testing) (now it should be falling) add ground plane node -> physical tab Bounce: 0 Bounce Forward: 0 Friction: 10 underneath add a merge node feed gravity node into merge node and connect to output (for testing) go back to test geo node and add attribute VOP (add under vellum constraints grain node) (set display flag on 2nd vellum constraints node and grain size to 0.02) inside add Anti-aliased Noise 3D Frequence: 10 10 10 Amplitude: 10 (this also defines clumbiness!) connect P with pos and noise with Cd add fit range node connect with noise Destination Min: 0.8 add bind export node connect with shift Name: attractionweight

adding colliders

add geo node with box inside then go into dopnet add static object node next to groundplane SOP path: select box object here fricion: 0 add merge node (feed static and groundplane) connect out to other merge node (keep input order or no simulation!) (uncheck testgeo to hide it)

caching

add geo node and dive inside add dop import node DOP Network: /obj/dopnet1 Object Mask: *Vellum* import style: Fetch Unpacked Geometry from DOP Network add color node color type: ramp from attribute attribute: attractionweight add file cache node (set frame range) file mode: Write files click save to disk add another file cache node but dont connect File Mode: Read files set display flag here

rendering grain particles in redshift

on geo node -> Redshift tab -> Particles -> check Render Object as Particles material needs to be assigned on top of geo node (not inside!)

src

https://www.youtube.com/watch?v=oqFPeicqPKE https://www.youtube.com/watch?v=AGPug-p_M2s https://www.youtube.com/watch?v=Iq2OktZtl14 https://www.sidefx.com/docs/houdini/grains/about.html