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xxyxxy last won the day on October 13

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  1. Workflow for creating terrain

    I am a terrain noob, but besides triplanar projection (or PxrRoundCube in RenderMan) you can also look into writing some custom code to break up texture repetition, as in this IQ article or detail textures in this David Rosen article: http://www.iquilezles.org/www/articles/texturerepetition/texturerepetition.htm https://www.gamasutra.com/blogs/DavidRosen/20091225/86222/Detail_Textures.php Note these techniques are both for real-time so might not give you the fidelity you are looking for.
  2. Specify light color in Kelvin?

    Awesome, thank you!!!
  3. Is there a way to feed in say 5000K as my light color in the Color Editor? I see there is a temperature slider in the TMI section but I don't understand how its [-1, 1] range maps to the normal black body gradient. Specifically, when it is at the lowest it seems to be a bright yellow instead of a deep red. Also (off-topic) is there any quick way to get a light to "look at" an object? I see there is a constraint I can add but I just want to do it quickly and interactively in the viewport.
  4. I literally didn't think to look on Orbolt until today... doh! Still curious if anybody knows about any materials for sale on gumroad or anything like that!
  5. Houdini at CppCon

    Maybe a little too inside baseball, but some interesting peeks at the internals of Houdini here:
  6. Emit particles from texture in 16.5

    Look into attrib from map, it does seem to require dense geometry as you mentioned:
  7. Houdini 18 Wishlist

    I would like SESI to unify the different ways to "SELECT ALL". I never know if I am supposed to tap "A", "N", "SHIFT-N" or "CTRL-A". I wish it would be like Blender where no matter what context you are in "A" toggles between "SELECT ALL" and "SELECT NONE" I would also like to see a Vulkan viewport so the GLROP (or I guess VKROP) would have access to the hardware intersection accelerator in the new AMD/NVIDIA/INTEL cards. If I supersample enough, like render at 128K for a 2K target, a hardware rasterized render isn't all that bad for lower budget mograph productions. I can live with the current IBL approximations to indirect lighting, but actual raytraced reflections and refractions using the upcoming Vulkan version of RTX would be so much nicer than screenspace approximations. The whole point is speed, the GLROP is currently way faster than even Redshift... it just looks dumpy.
  8. Thanks for the answers! So much info about instancing and style sheets, this is great. For the object appearance data tree question, it looks like if I name my groups and export as alembic then re-import the alembic I can assign materials to sub-groups in the object appearance data using packed edit: http://www.xuanprada.com/blog/2018/9/22/houdini-as-scene-assembler-part-02 Going to keep looking and see if there is a way to do this without the Alembic round-trip. Thanks again!
  9. Hey everybody! I am trying to work up my skills in surfacing by competing in this month's RenderMan challenge. I am currently using Mantra (because the RfH for RenderMan 22 doesn't come out for a few more weeks) but I have a few extremely basic questions about the workflow. I am using the Lookdev desktop, and using the built-in test geometry. 1. In the light bank data tree, I am only able to change intensity but not exposure. How can I change this? Do most lighters work in intensity or stops? 2. In the object appearance data tree, I am only able to assign materials at the object level. Is it possible to assign materials to groups from this UI? 3. When you lookdev terrain, is it more normal to scale your uv coordinates in the shader network or go back to the geo and use uvtransform to scale tiling textures up and down? Or do most people just use triplanar projections on background buildings and landscapes? 4. (Technical) I was looking into light instancing and found that with the template light you can write your own light shaders. But is that only in /shops? What is the current /mat way to write a light shader? 5. (Technical) I noticed that render times are faster with packed geometry, but then I lose all my material assignments. Why is rendering packed geometry faster? What is the currently accepted way to lookdev packed geometry without losing all your material assignments? 6. (Technical) How does light instancing work? It seems a little strange to me that the instancing tool is completely separate from the copy-to-points SOP. Is the instancing tool just running a for loop at IFD creation time? Are there any other common approaches to procedural light scattering?
  10. Hi! I am interested in acquiring some material libraries to learn more about shading. I'm looking for something akin to LollipopShaders for PRMan, except for Mantra. Does anybody know of any good free or paid material packs? I have already dug around in the 16.0 material library, have not updated to 16.5 to see if there are any new materials. Thanks!
  11. I want to spawn some particles (rendered as sprites) and have their entire quad drawn every time -- even if it the quad is intersecting with other scene geometry! Is this possible? I have done this in OpenGL where I just disable depth testing before I draw my particle system but I couldn't find any option like that in either the POP nodes or the shaders. One terrible option would be to render every frame twice, once with the scene geometry disabled and one with the particles disabled and then composite them on top of each other... but that can't be the correct answer. I want to do this because I am trying to recreate the kirakira filter on iOS which overlays the image with jumbo starburst sprites to simulate a combination of glints and diffraction spikes hitting a lens. intersecting_sprites
  12. kirakira popnet

    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.
  13. kirakira popnet

    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?