{"id":1127,"date":"2026-05-08T14:53:16","date_gmt":"2026-05-08T21:53:16","guid":{"rendered":"http:\/\/fx-td.com\/houdiniandchill\/?p=1127"},"modified":"2026-05-08T14:58:04","modified_gmt":"2026-05-08T21:58:04","slug":"archived-post-by-flakypastries-2","status":"publish","type":"post","link":"http:\/\/fx-td.com\/houdiniandchill\/2026\/05\/08\/archived-post-by-flakypastries-2\/","title":{"rendered":"Archived post by flakypastries"},"content":{"rendered":"<div class=\"postie-post\">\n<p class=\"\">yeah I am not sure this is possible either, since the texture is part of a shader evaluation but LPEs deal strictly with rays.<\/p>\n<p class=\"\">Depends on the Houdini version. In H21 we now have the RaySwitch VOP (finally!), so we can build a shader-based setup like this. If Efficient Emissive Sampling is on, Karma treats this like a light and contributes to direct rays.<br \/>\nYes it&#8217;s hacky but it actually works fairly well. You could expose a bunch of subnet inputs to facilitate later editing on the stage. And also in 21 we can then supply a stencil map via RGS on the card to cut it out. What I have not confirmed is how well Karma does importance sampling with this method (MIS on textured lighting effects has been hit or miss with Karma in my experience)<br \/>\nBut this at least gives easy separate controls over camera rays vs scene rays.<\/p>\n<p class=\"\">@Jonesy you were asking the other day about possible applications of the RaySwitch VOP<\/p>\n<p class=\"\">on the topc if LPEs, here is a list I have been maintaining of Karma LPEs as they crop up. These syntaxes have been tested in production but if anyone spots a problem please let me know. And if you know of other useful ones, I would love to know what they are. There are all kinds of things you can do.<br \/>\n<a href=\"https:\/\/gist.github.com\/tcrowson\/5d033817c63cf6cf27f3703e2df9462b\">gist.github.com\/tcrowson\/5d033817c63cf6cf27f3703e2df9462b<\/a><\/p>\n<p>Attachments in this post: <br \/><a href=\"http:\/\/fx-td.com\/houdiniandchill\/wp-content\/uploads\/discord\/20265305\/08\/26\/image.png\">http:\/\/fx-td.com\/houdiniandchill\/wp-content\/uploads\/discord\/20265305\/08\/26\/image.png<\/a><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>yeah I am not sure this is possible either, since the texture is part of a shader evaluation but LPEs deal strictly with rays. Depends on the Houdini version. In H21 we now have the RaySwitch VOP (finally!), so we can build a shader-based setup like this. If Efficient Emissive Sampling is on, Karma treats &hellip; <a href=\"http:\/\/fx-td.com\/houdiniandchill\/2026\/05\/08\/archived-post-by-flakypastries-2\/\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Archived post by flakypastries<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[5],"tags":[],"_links":{"self":[{"href":"http:\/\/fx-td.com\/houdiniandchill\/wp-json\/wp\/v2\/posts\/1127"}],"collection":[{"href":"http:\/\/fx-td.com\/houdiniandchill\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/fx-td.com\/houdiniandchill\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/fx-td.com\/houdiniandchill\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/fx-td.com\/houdiniandchill\/wp-json\/wp\/v2\/comments?post=1127"}],"version-history":[{"count":0,"href":"http:\/\/fx-td.com\/houdiniandchill\/wp-json\/wp\/v2\/posts\/1127\/revisions"}],"wp:attachment":[{"href":"http:\/\/fx-td.com\/houdiniandchill\/wp-json\/wp\/v2\/media?parent=1127"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/fx-td.com\/houdiniandchill\/wp-json\/wp\/v2\/categories?post=1127"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/fx-td.com\/houdiniandchill\/wp-json\/wp\/v2\/tags?post=1127"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}