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Renderman user group siggraph 20134/25/2023 ![]() Outside of sculpt mode, doing the subdivision surfaces on the GPU with or without displacement should be quite nice, especially for animators to see realtime playback of the full subdivided and displaced mesh. You’d need to bake down the displacement each time which is just going to make things slower. My guess is that for display in sculpt mode itself OpenSubdiv is not so useful, as you are editing the tessellated vertex positions directly there and retessellating them each time will not help. These are planned to be added by Dreamworks, along with some performance optimizations.įor Blender we also still have to see how this all fits with displacement and multires sculpting. There’s still some things missing in the library that we need for Blender, in particular non-manifold meshes and smooth UVs. modeling with creases and fewer edge loops, and think it’s worth the investment to ensure they do not have to switch to some other standard that could win later on. They have a lot invested in their workflow, e.g. Pixar is open sourcing OpenSubdiv mainly to push it as the subdivision surface standard, and will be proposing to include it in OpenGL later this year. For more in-depth stuff check the collection of links here: Some notes I took during SIGGRAPH, mostly technical and render related stuff that I found interesting. ![]() ReferencesRibTools’ web site“The RenderMan Interface Specification” (aka RISpec)“Rendering with REYES” (from Pixar)“Production Rendering” (Ian Stephenson Ed.)“Advanced RenderMan” (by A.Apodaca and L.Brecht Van Lommel has posted his observations from SIGGRAPH on the dev maillist. complex stuffComes with other issues:Cracks when tessellating, non-planar micropolys, front plane clipping, etc.but someone’s got to try it 8)28 Prospects for RibToolsWhat role will REYES play for real-time ?The architecture bodes well with multi-core, vector processors or even GPGPUDisplacement and curved surfaces are best with smaller-than-a-pixel polygons anywayDevelop, learn and innovateDon’t let the others decide for you.Fully programmable graphics hardware is comingOff-line rendering ?Much more complex, but no real-time constraintsDX11 tessellation.almost micro-polygons! *RenderAnts: REYES on GPGPUSiggraph 2008, 2009 **27* From Unigine’s Direct3D 11 tech demo ** Image from RenderAnts rendererĬons and problemsRequires highly programmable hardware (best if with a flexible texture unit)The “RenderMan interface” is a fairly deep standard to followShader compilers, optimizers. What’s “Small Enough” ?When most sub-patches fit in a single bucketWhen dicing(see later) produces a suitable number of samples (sweet spot for performance)Sub-patch insidea single bucketOptimalSub-patch touchestwo or more bucketsNot OptimalA bucket11ĭiceSmall enough sub-patches are dicedGenerate a dense grid of samples (1 pixel-per-sample or more.)1 pixelSmall enough n_samples max_samples is set for performance reasonsand to avoid distortion12ĭisplaceApply a displacement shader to the position of the samplesmyDisplace()OpenCL, CUDA, ?16x25 Split (5)Split recursively until every sub-patch is “small enough”…Small enough. Split (4)Calculate the bounds of the new sub-patchesStill too large9 Split (3)When too large, split the patchIt’s easy with parametric primitives:Pnew = f(unew, vnew)New split points8 ![]() Split (2)Calculate the bounding box in screen-space…test against predetermined max screen areaHere, the bounding box is too large.7 Split (1)A parametric surface: P = f(u,v)Split until “small enough” size (estimated) on screen6 REYES featuresNative support for high level surfacesDynamic LODCompact representationSubdivide per-frame based on size on screenDisplace geometry from texturesHigh quality filteringEasier to deal with translucency, motion-blur, etc.Can be used together with ray-tracing4 RenderMan compliant ?Defines a renderer with some basic capabilities such as:A RenderMan graphics state machineHidden surface eliminationPixel filtering and anti-aliasingUser programmable shadersTexture mappingEtc…3 (“Pixar” from 1986)First used in 1984 in Start Trek II.still used today in Pixar’s Photorealistic RenderMan2* Images, from top, are copyright of Paramount Pictures and Pixar (subsidiary of The Walt Disney Company) Implementing a modern, RenderMan compliant, REYES rendererDavide (contact: davide )1Ībout REYESReyes or REYES (Renders Everything You Ever Saw)A flexible renderer, developed by Lucasfilm CG div. Implementing a modern, RenderMan compliant, REYES renderer
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