Nicholas Ralabate Posted January 5, 2018 Share Posted January 5, 2018 Hey gang! I was curious how one would recreate something like the kirakira sparkle filter in Houdini. It looks like this: https://www.glamour.com/story/kirakira-sparkle-filter-app I know how I would do it in OpenGL, basically threshold the video frame then use the brightest pixels to emit a simple billboarded quad... (although I'm not sure why lights don't emit sparkles but that is besides the point). How would one use Houdini to do a similar effect? I have not worked with video data yet... the first thing I thought of was using COPS to get pixel information but it seems like COPS would have to shoot data back up the pipeline to emit some new geometry in the particle system. Maybe there is some sort of way to call POP.emit from COPS vex? I wonder if the workflow would be the same in Nuke, you would still have to go from screenspace pixel data back up to worldspace geometric data to emit the particle. Also, this is semi-related, but I was trying to get my particles to display a lens flare texture... what is the point of the POP Sprite node? It seems like I am able to assign a texture map just fine by using the Mantra Classic Shader material with "emissive" enabled to read from a map. What is the usual way that POP particles render as camera-facing billboarded quads? Quote Link to comment Share on other sites More sharing options...
Jason Posted January 5, 2018 Share Posted January 5, 2018 Oh you want to do this directly in the viewport? I was hoping Render COP pointing to a OpenGL ROP would let you grab the viewport, or failing that some kind of python function to yank the GeometryViewport and then do your thresholding and use that to scatter colored points on the viewing plane - your sprites. Sadly the very first step doesn't support opengl rendering directly into COPs, and I can't find an appropriate python function. What speeds are you looking at wanting? Realtime? If so you might be in HDK Viewport Render Hook territory. Quote Link to comment Share on other sites More sharing options...
Nicholas Ralabate Posted January 5, 2018 Author Share Posted January 5, 2018 No, sorry! I am new to Houdini but have a background in OpenGL, maybe I should have kept that to myself! I am curious how to do this with Mantra. Quote Link to comment Share on other sites More sharing options...
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