Radial sort around intersections, the how and why

This is a houdini tutorial that will show you how to do a radial sort around any number of intersection points in a poly line geometry, as long as a couple of requirements have been met. We go through how to prepare your geo for the sorting to work, then how to do the sorting, and then finally I show a little example of what you can do when the sorting has been done. The tutorial has been made with houdini 20. Copyright and creation by Dag Kjetsa Please note that this video has chapters, so feel free to explore them. Links to further content: Indie Pixel tutorial on radial sorting: https://www.youtube.com/watch?v=LsqF5lFsvog&t=2s Dokai tutorial (relevant section around min 03:00): https://www.youtube.com/watch?v=bTlY9ahThdQ&t=183s SideFX documentation on the atan2 function: https://www.sidefx.com/docs/houdini/vex/functions/atan2.html Wikipedia link to the atan2 function: https://en.wikipedia.org/wiki/Atan2 00:00 - Chapter 1 - introduction 00:42 - Chapter 2 - test case vs real scenario 01:55 - Chapter 3 - defining intersections 03:15 - Chapter 4 - setting up the rules 04:01 - Chapter 5 - starting prep - ensuring correct primitive numbers 05:48 - Chapter 6 - splitting primitives 07:34 - Chapter 7 - resampling the polylines 10:14 - Chapter 8 - vex code - what are the requirements? 11:24 - Chapter 9 - vex code - calculate a vector towards the intersection points 18:13 - Chapter 10 - vex code - calculate a sort value attribute 20:40 - Chapter 11 - do the sorting 21:22 - Chapter 12 - checking that the sorting works as it should 22:54 - Chapter 13 - the special case of three "armed" intersections 23:52 - Chapter 14 - demonstrating how solid the system is 25:26 - Chapter 15 - why is this sorting useful? 27:27 - Chapter 16 - example of the usefulness of the radial sort 31:14 - Chapter 17 - outro #3d #houdini #vfx #vfxartists #postproduction #proceduralmodeling #visualeffects #proceduralism