mirror of
https://github.com/PixarAnimationStudios/OpenSubdiv
synced 2024-11-30 15:20:07 +00:00
e96bf355e0
- fixed missing PatchDescriptor functionality for Loop triangle
- add new PatchDescriptor::Type for Gregory triangle
- extended PatchParam boundary mask from 4 to 5 bits (!)
- added new PatchParam methods for parameterization of triangles
- extended PatchMap to support triangular patches
- added basis evaluation for triangular patch types
333 lines
12 KiB
C++
333 lines
12 KiB
C++
//
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// Copyright 2013 Pixar
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//
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// Licensed under the Apache License, Version 2.0 (the "Apache License")
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// with the following modification; you may not use this file except in
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// compliance with the Apache License and the following modification to it:
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// Section 6. Trademarks. is deleted and replaced with:
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//
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// 6. Trademarks. This License does not grant permission to use the trade
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// names, trademarks, service marks, or product names of the Licensor
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// and its affiliates, except as required to comply with Section 4(c) of
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// the License and to reproduce the content of the NOTICE file.
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//
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// You may obtain a copy of the Apache License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the Apache License with the above modification is
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// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied. See the Apache License for the specific
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// language governing permissions and limitations under the Apache License.
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//
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#ifndef OPENSUBDIV3_FAR_PATCH_PARAM_H
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#define OPENSUBDIV3_FAR_PATCH_PARAM_H
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#include "../version.h"
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#include "../far/types.h"
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namespace OpenSubdiv {
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namespace OPENSUBDIV_VERSION {
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namespace Far {
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/// \brief Patch parameterization
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///
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/// Topological refinement splits coarse mesh faces into refined faces.
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///
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/// This patch parameterzation describes the relationship between one
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/// of these refined faces and its corresponding coarse face. It is used
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/// both for refined faces that are represented as full limit surface
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/// parametric patches as well as for refined faces represented as simple
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/// triangles or quads. This parameterization is needed to interpolate
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/// primvar data across a refined face.
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///
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/// The U,V and refinement level parameters describe the scale and offset
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/// needed to map a location on the patch between levels of refinement.
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/// The encoding of these values exploits the quad-tree organization of
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/// the faces produced by subdivision. We encode the U,V origin of the
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/// patch using two 10-bit integer values and the refinement level as
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/// a 4-bit integer. This is sufficient to represent up through 10 levels
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/// of refinement.
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///
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/// Special consideration must be given to the refined faces resulting from
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/// irregular coarse faces. We adopt a convention similar to Ptex texture
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/// mapping and define the parameterization for these faces in terms of the
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/// regular faces resulting from the first topological splitting of the
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/// irregular coarse face.
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///
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/// When computing the basis functions needed to evaluate the limit surface
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/// parametric patch representing a refined face, we also need to know which
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/// edges of the patch are interpolated boundaries. These edges are encoded
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/// as a boundary bitmask identifying the boundary edges of the patch in
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/// sequential order starting from the first vertex of the refined face.
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///
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/// A sparse topological refinement (like feature adaptive refinement) can
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/// produce refined faces that are adjacent to faces at the next level of
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/// subdivision. We identify these transitional edges with a transition
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/// bitmask using the same encoding as the boundary bitmask.
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///
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/// For triangular subdivision schemes we specify the parameterization using
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/// a similar method. Alternate triangles at a given level of refinement
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/// are parameterized from their opposite corners and encoded as occupying
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/// the opposite diagonal of the quad-tree hierarchy. The third barycentric
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/// coordinate is dependent on and can be derived from the other two
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/// coordinates. This encoding also takes inspiration from the Ptex
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/// texture mapping specification.
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///
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/// Bitfield layout :
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///
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/// Field0 | Bits | Content
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/// -----------|:----:|------------------------------------------------------
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/// faceId | 28 | the faceId of the patch
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/// transition | 4 | transition edge mask encoding
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///
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/// Field1 | Bits | Content
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/// -----------|:----:|------------------------------------------------------
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/// level | 4 | the subdivision level of the patch
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/// nonquad | 1 | whether patch is refined from a non-quad face
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/// regular | 1 | whether patch is regular
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/// unused | 1 | unused
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/// boundary | 5 | boundary edge mask encoding
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/// v | 10 | log2 value of u parameter at first patch corner
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/// u | 10 | log2 value of v parameter at first patch corner
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///
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/// Note : the bitfield is not expanded in the struct due to differences in how
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/// GPU & CPU compilers pack bit-fields and endian-ness.
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///
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/*!
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\verbatim
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Quad Patch Parameterization
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(0,1) (1,1)
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+-------+-------+---------------+
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| | | |
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| L2 | L2 | |
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|0,3 |1,3 | |
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+-------+-------+ L1 |
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| | | |
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| L2 | L2 | |
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|0,2 |1,2 |1,1 |
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+-------+-------+---------------+
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| | |
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| | |
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| | |
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| L1 | L1 |
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| | |
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|0,0 |1,0 |
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+---------------+---------------+
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(0,0) (1,0)
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\endverbatim
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*/
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/*!
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\verbatim
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Triangle Patch Parameterization
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(0,1) (1,1) (0,1,0)
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+-------+-------+---------------+ +
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| \ | \ | \ | | \
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|L2 \ |L2 \ | \ | | \
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|0,3 \ |1,3 \ | \ | | L2 \
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+-------+-------+ \ | +-------+
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| \ | \ | L1 \ | | \ L2 | \
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|L2 \ |L2 \ | \ | | \ | \
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|0,2 \ |1,2 \ |1,1 \ | | L2 \ | L2 \
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+-------+-------+---------------+ +-------+-------+
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| \ | \ | | \ | \
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| \ | \ | | \ | \
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| \ | \ | | \ L1 | \
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| \ | \ | | \ | \
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| L1 \ | L1 \ | | L1 \ | L1 \
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| \ | \ | | \ | \
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|0,0 \ |1,0 \ | | \ | \
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+---------------+---------------+ +---------------+---------------+
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(0,0) (1,0) (0,0,1) (1,0,0)
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\endverbatim
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*/
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struct PatchParam {
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/// \brief Sets the values of the bit fields
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///
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/// @param faceid face index
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///
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/// @param u value of the u parameter for the first corner of the face
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/// @param v value of the v parameter for the first corner of the face
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///
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/// @param depth subdivision level of the patch
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/// @param nonquad true if the root face is not a quad
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///
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/// @param boundary 5-bits identifying boundary edges (and verts for tris)
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/// @param transition 4-bits identifying transition edges
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///
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/// @param regular whether the patch is regular
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///
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void Set(Index faceid, short u, short v,
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unsigned short depth, bool nonquad,
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unsigned short boundary, unsigned short transition,
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bool regular = false);
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/// \brief Resets everything to 0
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void Clear() { field0 = field1 = 0; }
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/// \brief Returns the faceid
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Index GetFaceId() const { return Index(unpack(field0,28,0)); }
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/// \brief Returns the log2 value of the u parameter at
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/// the first corner of the patch
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unsigned short GetU() const { return (unsigned short)unpack(field1,10,22); }
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/// \brief Returns the log2 value of the v parameter at
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/// the first corner of the patch
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unsigned short GetV() const { return (unsigned short)unpack(field1,10,12); }
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/// \brief Returns the transition edge encoding for the patch.
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unsigned short GetTransition() const { return (unsigned short)unpack(field0,4,28); }
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/// \brief Returns the boundary edge encoding for the patch.
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unsigned short GetBoundary() const { return (unsigned short)unpack(field1,5,7); }
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/// \brief True if the parent base face is a non-quad
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bool NonQuadRoot() const { return (unpack(field1,1,4) != 0); }
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/// \brief Returns the level of subdivision of the patch
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unsigned short GetDepth() const { return (unsigned short)unpack(field1,4,0); }
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/// \brief Returns the fraction of unit parametric space covered by this face.
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float GetParamFraction() const;
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/// \brief A (u,v) pair in the fraction of parametric space covered by this
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/// face is mapped into a normalized parametric space.
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///
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/// @param u u parameter
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/// @param v v parameter
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///
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template <typename REAL>
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void Normalize( REAL & u, REAL & v ) const;
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template <typename REAL>
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void NormalizeTriangle( REAL & u, REAL & v ) const;
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/// \brief A (u,v) pair in a normalized parametric space is mapped back into the
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/// fraction of parametric space covered by this face.
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///
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/// @param u u parameter
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/// @param v v parameter
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///
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template <typename REAL>
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void Unnormalize( REAL & u, REAL & v ) const;
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template <typename REAL>
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void UnnormalizeTriangle( REAL & u, REAL & v ) const;
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/// \brief Returns if a triangular patch is parametrically rotated 180 degrees
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bool IsTriangleRotated() const;
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/// \brief Returns whether the patch is regular
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bool IsRegular() const { return (unpack(field1,1,5) != 0); }
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unsigned int field0:32;
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unsigned int field1:32;
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private:
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unsigned int pack(unsigned int value, int width, int offset) const {
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return (unsigned int)((value & ((1<<width)-1)) << offset);
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}
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unsigned int unpack(unsigned int value, int width, int offset) const {
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return (unsigned int)((value >> offset) & ((1<<width)-1));
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}
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};
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typedef std::vector<PatchParam> PatchParamTable;
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typedef Vtr::Array<PatchParam> PatchParamArray;
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typedef Vtr::ConstArray<PatchParam> ConstPatchParamArray;
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inline void
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PatchParam::Set(Index faceid, short u, short v,
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unsigned short depth, bool nonquad,
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unsigned short boundary, unsigned short transition,
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bool regular) {
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field0 = pack(faceid, 28, 0) |
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pack(transition, 4, 28);
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field1 = pack(u, 10, 22) |
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pack(v, 10, 12) |
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pack(boundary, 5, 7) |
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pack(regular, 1, 5) |
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pack(nonquad, 1, 4) |
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pack(depth, 4, 0);
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}
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inline float
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PatchParam::GetParamFraction( ) const {
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return 1.0f / (float)(1 << (GetDepth() - NonQuadRoot()));
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}
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template <typename REAL>
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inline void
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PatchParam::Normalize( REAL & u, REAL & v ) const {
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REAL fracInv = (REAL)(1.0f / GetParamFraction());
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u = u * fracInv - (REAL)GetU();
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v = v * fracInv - (REAL)GetV();
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}
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template <typename REAL>
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inline void
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PatchParam::Unnormalize( REAL & u, REAL & v ) const {
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REAL frac = (REAL)GetParamFraction();
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u = (u + (REAL)GetU()) * frac;
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v = (v + (REAL)GetV()) * frac;
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}
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inline bool
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PatchParam::IsTriangleRotated() const {
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return (GetU() + GetV()) >= (1 << GetDepth());
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}
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template <typename REAL>
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inline void
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PatchParam::NormalizeTriangle( REAL & u, REAL & v ) const {
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if (IsTriangleRotated()) {
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REAL fracInv = (REAL)(1.0f / GetParamFraction());
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int depthFactor = 1 << GetDepth();
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u = (REAL)(depthFactor - GetU()) - (u * fracInv);
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v = (REAL)(depthFactor - GetV()) - (v * fracInv);
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} else {
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Normalize(u, v);
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}
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}
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template <typename REAL>
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inline void
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PatchParam::UnnormalizeTriangle( REAL & u, REAL & v ) const {
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if (IsTriangleRotated()) {
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REAL frac = GetParamFraction();
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int depthFactor = 1 << GetDepth();
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u = ((REAL)(depthFactor - GetU()) - u) * frac;
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v = ((REAL)(depthFactor - GetV()) - v) * frac;
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} else {
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Unnormalize(u, v);
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}
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}
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} // end namespace Far
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} // end namespace OPENSUBDIV_VERSION
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using namespace OPENSUBDIV_VERSION;
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} // end namespace OpenSubdiv
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#endif /* OPENSUBDIV3_FAR_PATCH_PARAM */
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