Category: cgi-math

Archived post by mysterypancake

added some info about a method i posted earlier to make a coordinate system along curves: github.com/MysteryPancake/Houdini-Fun/tree/main#coordinate-system-along-curves

Attachments in this post:
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20265405/31/26/curve_frame_planes.png
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20265405/31/26/noise_along_curve_volume.webp
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20265405/31/26/pig_along_curve.webp
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20265405/31/26/curve_unroll.webp

Archived post by mattiasmalmer

I made a visualizer that might be a little bit helpful when doing Half-Edge antics.
You just drop it and set it as template. (make sure your template geo settings are not ghosted/faded or you will miss out on my lovely selection of colors)

Attachments in this post:
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20265904/19/26/image.png
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20265904/19/26/Hedge_VIS.hip

Archived post by sniperjake945

i know we’ve all moved on from the hex sphere conversation but i will say the planarization method sidefx is using in the facet sop is actually so un flattering. Im assuming its generating some kind of per face normal and then using the average position and then projecting wrt to that. but like there are so many better methods… For instance, using the local/local solve from: roipo.github.io/publication/poranne-2013-interactive/planarization.pdf
We get the result on the right after 50 iterations (which is planar for all faceted polygons) vs what’s coming out of the facet sop with make planar turned on (left)…
The file also includes an example of the local global solve (or at least to the best of my ability it does)

if we planarize before faceting we can get even better results in some cases. Like this sphere example. The left is facet and the right is the local/local solve (faceted after).

Attachments in this post:
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20250810/18/25/image.png
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20250810/18/25/jr_planarize_polygons.hip

Archived post by niconghiem

Was toying with the Linear Solver at work this week and ended up writing a Spectral Clustering algorithm that can somehow guess the number of clusters. Finally found a good scenario where it actually made sense to use the Spare_parminputindex trick (and not me obfuscating stuff for no reason <:hyperlaugh:443322845406298112> )

Unfortunately with those data-analysis type of things, the algorithm is not really scale dependent and results vary a lot if the parameters (standard deviation/distance between clusters) are in the good ballpark tho for my use case at work (clustering crowds) those do not really vary much so it’s pretty solid in most cases

Attachments in this post:
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20250806/12/25/dev_spectral_clustering.mp4
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20250806/12/25/spectral_clustering_dev.hiplc