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https://github.com/PixarAnimationStudios/OpenSubdiv
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5415bc23b9
@ -274,9 +274,6 @@ with 16, 12, 9 and 4 control vertices respectively.
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that we can eventually get rid of the current re-ordering step applied
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to the control vertex indices.
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We also intend to consolidate all bi-cubic patch types into using 16
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control vertices, which will deprecate the *Boundary* and *Corner* types.
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Patch Transitions
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*****************
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@ -330,7 +327,7 @@ created by combining the list of control vertices from the 1-ring.
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With iterative subdivision, each refinement step is dependent upon the previous
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subdivision step being completed, and a substantial number of steps may be
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required in order approximate the limit : each subdivision step incurs an
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O(4:superscript:`n`) growing amount of computations.
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O(4\ :superscript:`n`) growing amount of computations.
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Instead, once the weights of the contributing coarse control vertices for a
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given refined vertex have been factorized, it is possible to apply the stencil
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@ -40,7 +40,7 @@ Introduction
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OpenSubdiv is a set of open source libraries that implement high performance
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subdivision surface (subdiv) evaluation on massively parallel CPU and GPU
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architectures. This codepath is optimized for drawing deforming surfaces with
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architectures. This code path is optimized for drawing deforming surfaces with
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static topology at interactive framerates. The resulting limit surfaces are a match
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for Pixar's Renderman specification within numerical precision limits.
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@ -118,8 +118,8 @@ a series of regression tests that compare the methods to each other.
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* **Beta Issues**
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Face-varying smooth data interpolation is currently not supported in **Osd**.
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"Smooth UV" modes of various DCC applications are not supported (yet).
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Face-varying smooth data interpolation is currently only supported in
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**Osd** through refinement and limit points but not in the PatchTables.
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----
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@ -146,6 +146,7 @@ HLSL-Compute **Compute** back-end can be paired effectively with a DX11
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HLSL-Shading **Draw** back-end. Some pairings however are not possible, as
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there may be no data inter-operation paths available (ex: transferring DX11
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compute SRVs to GL texture buffers).
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----
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Contexts & Controllers
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@ -147,7 +147,7 @@ instead.
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Stencils remove all data dependencies and simplify all the computations into a
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single trivial kernel. This simplification results in a faster pre-computation
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stage, faster execution on GPU, with fewer driver overheads. The new stencil
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stage, faster execution on GPU, with less driver overhead. The new stencil
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tables Compute back-end is supported on all the same platforms as previous
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releases (except GCD).
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@ -341,19 +341,19 @@ functionality that has long been missing from evaluation and display.
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Enabling workflows at larger scales will require improvements on several fronts:
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* Handle more primitives, but with fewer overheads:
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* Handle more primitives, but with less overhead:
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* Reduce Compute kernel launches,which we will achieve using stencils instead
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* Reduce Compute kernel launches, which we will achieve using stencils instead
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of subdivision tables
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* Reduce Draw calls by addressing the combinatorial explosion of tessellation
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shaders
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* Provide back-ends for next-gen APIs (D3D12, Mantle, Metal, GL 5.x)
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* Provide back-ends for next-gen APIs (D3D12, Mantle, Metal, Vulkan, etc.)
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* Handle more semi-sharp creases: feature isolation needs to become much more
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efficient to allow for complete creative freedom in using the feature.
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* Faster topology analysis
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As for missing functionality, as the potential standard for evaluation and display
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As the potential standard for evaluation and display
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of subdivision surfaces, OpenSubdiv is still lacking in its support of subdivision
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schemes other than Catmark -- specifically Loop. Ultimately the same level of
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performance and functionality achieved with Catmark should be available for Loop,
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@ -118,7 +118,7 @@ A means to control edge curvature
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++++++++++++++++++++
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Implement Osd::Draw Context & Controllers for next-gen GPU APIs such as
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Mantle, Metal, DX12, GL Next.
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Mantle, Metal, DX12, Vulkan.
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Regression testing
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++++++++++++++++++
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@ -38,8 +38,8 @@ Subdivision Core (Sdc)
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Sdc is the lowest level layer in OpenSubdiv. Its intent is to separate
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the core subdivision details from any particular representation of a mesh
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(it was previously bound to Hbr) to facilate other classes both internal
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and external to OpenSubdiv generating consistent results.
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(it was previously bound to Hbr) to facilitate the generation of consistent
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results to other mesh representations, both internal and external to OpenSubdiv.
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The functionality can be divided roughly into three sections:
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@ -86,7 +86,7 @@ into a single object (the equivalent of an integer in this case) that are passed
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around to other Sdc classes and/or methods and are expected to be used at a higher
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level both within OpenSubdiv and externally. By aggregating the options and
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passing them around as a group, it allows us to extend the set easily in future
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without the need to rewire a lot of interfaces to accomodate the new choice.
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without the need to rewire a lot of interfaces to accommodate the new choice.
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Clients can enables new choices at the highest level and be assured that they will
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propagate to the lowest level where they are relevant.
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@ -164,7 +164,7 @@ minimize the amount of code specific to each scheme.
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The computation of mask weights for subdivided vertices is the most significant
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contribution of Sdc. The use of semi-sharp creasing with each
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non-linear subdivision scheme complicates what are otherwise simple
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masks detemined solely by the topology, and packaging that functionality to
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masks determined solely by the topology, and packaging that functionality to
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achieve both the generality and efficiency desired has been a challenge.
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Mask queries are defined in the *Scheme* class template, which has
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@ -299,10 +299,10 @@ Methods dealing with the collections of weights defining a mask are typically
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parameterized by a *MASK* template parameter that contains the weights. The set of
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mask weights is currently divided into vertex-weights, edge-weights and
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face-weights -- consistent with previous usage in OpenSubdiv and providing some
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useful correllation between the full set of weights and topology. The
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useful correlation between the full set of weights and topology. The
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vertex-weights refer to parent vertices incident the parent component from which a
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vertex originated, the edge-weights the vertices opposite incident edges of the
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parent, and the face-weights the center of indicent parent faces. Note the latter
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parent, and the face-weights the center of incident parent faces. Note the latter
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is **NOT** in terms of vertices of the parent but potentially vertices in the child
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originating from faces of the parent. This has been done historically in
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OpenSubdiv but is finding less use -- particularly when it comes to providing
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@ -43,7 +43,7 @@ bicubic patches such as BSplines or NURBS.
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However, while they do provide a reliable smooth limit surface definition,
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bi-cubic patch surfaces are limited to 2-dimensional topologies, which only
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describes a very small fraction of real-world shapes. This fundamental
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describe a very small fraction of real-world shapes. This fundamental
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parametric limitation requires authoring tools to implement at least the
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following functionalities:
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@ -130,15 +130,13 @@ gracefully.
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**Beta Issues**
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As of 3.0.0 Beta release, non-manifold topology has limited support. Most
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non-manifold configurations (with the exception of degenerate edges) are
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supported for refinement and subdivision. But some factories, such as the
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patch tables, do not support them. The interpolation associated with
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non-manifold features currently treats them as infinitely sharp features --
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smooth rules are possible but exactly what they should be is unclear. We
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intend to fully specify and implement a set of interpolation rules in a
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future release of OpenSubdiv. Until then the results should be considered
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undefined.
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As of 3.0.0 Beta release, most non-manifold configurations (with the
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exception of degenerate edges) are supported for refinement and subdivision.
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The interpolation associated with non-manifold features currently treats
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them as infinitely sharp features -- smooth rules are possible but exactly
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what they should be is unclear. We intend to fully specify and implement a
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set of interpolation rules in a future release of OpenSubdiv. Until then
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the results should be considered undefined.
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----
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@ -62,5 +62,5 @@ Here are example commands for building an OpenSubdiv application on several arch
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**Note:**
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HBR uses the offsetof macro on a templated struct, which appears to spurriously set off a
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warning in both gccc and Clang. It is recommended to turn the warning off with the
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warning in both gcc and Clang. It is recommended to turn the warning off with the
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*-Wno-invalid-offsetof* flag.
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@ -82,20 +82,6 @@ Others exist to represent the following:
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* common low-level utilities, e.g. simple array classes
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.. container:: notebox
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**Beta Issues**
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Being intended for internal use, any changes to *Vtr* should not impact public
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interfaces. Regardless, its worth noting some of the work planned:
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* improve non-manifold support to handle degenerate edges
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* potential nesting of FVar classes within *Level* and *Refinement*
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* potential specializations for regular *Levels* and *Refinements*
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Priority will be given to satisfying functional needs.
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Vtr::Level
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==========
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