AuroraMiddleware/OpenSubdiv
1
0
Fork 0
mirror of https://github.com/PixarAnimationStudios/OpenSubdiv synced 2024-12-01 07:40:07 +00:00
Code Issues Releases Wiki Activity
e3db2c94a6
OpenSubdiv/opensubdiv/sdc/loopScheme.h
barfowl e3db2c94a6 Minor performance improvements to Sdc limit masks for the regular case: 
- simple loop unrolling and branch reduction in Loop and Catmark limits
2015-05-19 15:49:19 -07:00

582 lines
20 KiB
C++
Raw Blame History

//
// Copyright 2014 DreamWorks Animation LLC.
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
// names, trademarks, service marks, or product names of the Licensor
// and its affiliates, except as required to comply with Section 4(c) of
// the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache License.
//
#pragma once
#ifndef OPENSUBDIV3_SDC_LOOP_SCHEME_H
#define OPENSUBDIV3_SDC_LOOP_SCHEME_H
#include "../version.h"
#include "../sdc/scheme.h"
#include <cassert>
namespace OpenSubdiv {
namespace OPENSUBDIV_VERSION {
namespace Sdc {
//
// Specializations for Sdc::Scheme<SCHEME_LOOP>:
//
//
//
// Loop traits:
//
template <>
inline Split Scheme<SCHEME_LOOP>::GetTopologicalSplitType() { return SPLIT_TO_TRIS; }
template <>
inline int Scheme<SCHEME_LOOP>::GetRegularFaceSize() { return 3; }
template <>
inline int Scheme<SCHEME_LOOP>::GetRegularVertexValence() { return 6; }
template <>
inline int Scheme<SCHEME_LOOP>::GetLocalNeighborhoodSize() { return 1; }
//
// Protected methods to assign the two types of masks for an edge-vertex --
// Crease and Smooth.
//
// The Crease case does not really need to be speciailized, though it may be
// preferable to define all explicitly here.
//
template <>
template <typename EDGE, typename MASK>
inline void
Scheme<SCHEME_LOOP>::assignCreaseMaskForEdge(EDGE const&, MASK& mask) const
{
mask.SetNumVertexWeights(2);
mask.SetNumEdgeWeights(0);
mask.SetNumFaceWeights(0);
mask.SetFaceWeightsForFaceCenters(false);
mask.VertexWeight(0) = 0.5f;
mask.VertexWeight(1) = 0.5f;
}
template <>
template <typename EDGE, typename MASK>
inline void
Scheme<SCHEME_LOOP>::assignSmoothMaskForEdge(EDGE const& edge, MASK& mask) const
{
int faceCount = edge.GetNumFaces();
mask.SetNumVertexWeights(2);
mask.SetNumEdgeWeights(0);
mask.SetNumFaceWeights(faceCount);
mask.SetFaceWeightsForFaceCenters(false);
//
// This is where we run into the issue of "face weights" -- we want to weight the
// face-centers for Catmark, but face-centers are not generated for Loop. So do
// we make assumptions on how the mask is used, assign some property to the mask
// to indicate how they were assigned, or take input from the mask itself?
//
// Regardless, we have two choices:
// - face-weights are for the vertices opposite the edge (as in Hbr):
// vertex weights = 0.375f;
// face weights = 0.125f;
//
// - face-weights are for the face centers:
// vertex weights = 0.125f;
// face weights = 0.375f;
//
// Coincidentally the coefficients are the same but reversed.
//
typedef typename MASK::Weight Weight;
Weight vWeight = mask.AreFaceWeightsForFaceCenters() ? 0.125f : 0.375f;
Weight fWeight = mask.AreFaceWeightsForFaceCenters() ? 0.375f : 0.125f;
mask.VertexWeight(0) = vWeight;
mask.VertexWeight(1) = vWeight;
if (faceCount == 2) {
mask.FaceWeight(0) = fWeight;
mask.FaceWeight(1) = fWeight;
} else {
// The non-manifold case is not clearly defined -- we adjust the above
// face-weight to preserve the ratio of edge-center and face-centers:
fWeight *= 2.0f / (Weight) faceCount;
for (int i = 0; i < faceCount; ++i) {
mask.FaceWeight(i) = fWeight;
}
}
}
//
// Protected methods to assign the three types of masks for a vertex-vertex --
// Corner, Crease and Smooth (Dart is the same as Smooth).
//
// Corner and Crease do not really need to be speciailized, though it may be
// preferable to define all explicitly here.
//
template <>
template <typename VERTEX, typename MASK>
inline void
Scheme<SCHEME_LOOP>::assignCornerMaskForVertex(VERTEX const&, MASK& mask) const
{
mask.SetNumVertexWeights(1);
mask.SetNumEdgeWeights(0);
mask.SetNumFaceWeights(0);
mask.SetFaceWeightsForFaceCenters(false);
mask.VertexWeight(0) = 1.0f;
}
template <>
template <typename VERTEX, typename MASK>
inline void
Scheme<SCHEME_LOOP>::assignCreaseMaskForVertex(VERTEX const& vertex, MASK& mask,
int const creaseEnds[2]) const {
typedef typename MASK::Weight Weight;
int valence = vertex.GetNumEdges();
mask.SetNumVertexWeights(1);
mask.SetNumEdgeWeights(valence);
mask.SetNumFaceWeights(0);
mask.SetFaceWeightsForFaceCenters(false);
Weight vWeight = 0.75f;
Weight eWeight = 0.125f;
mask.VertexWeight(0) = vWeight;
for (int i = 0; i < valence; ++i) {
mask.EdgeWeight(i) = 0.0f;
}
mask.EdgeWeight(creaseEnds[0]) = eWeight;
mask.EdgeWeight(creaseEnds[1]) = eWeight;
}
template <>
template <typename VERTEX, typename MASK>
inline void
Scheme<SCHEME_LOOP>::assignSmoothMaskForVertex(VERTEX const& vertex, MASK& mask) const
{
typedef typename MASK::Weight Weight;
int valence = vertex.GetNumFaces();
mask.SetNumVertexWeights(1);
mask.SetNumEdgeWeights(valence);
mask.SetNumFaceWeights(0);
mask.SetFaceWeightsForFaceCenters(false);
// Specialize for the regular case: 1/16 per edge-vert, 5/8 for the vert itself:
Weight eWeight = (Weight) 0.0625f;
Weight vWeight = (Weight) 0.625f;
if (valence != 6) {
// From HbrLoopSubdivision<T>::Subdivide(mesh, vertex):
// - could use some lookup tables here for common irregular valence (5, 7, 8)
// or all of these cosf() calls will be adding up...
Weight invValence = 1.0f / (Weight) valence;
Weight beta = 0.25f * cosf((Weight)M_PI * 2.0f * invValence) + 0.375f;
eWeight = (0.625f - (beta * beta)) * invValence;;
vWeight = 1.0f - (eWeight * (Weight)valence);
}
mask.VertexWeight(0) = vWeight;
for (int i = 0; i < valence; ++i) {
mask.EdgeWeight(i) = eWeight;
}
}
//
// Limit masks for position:
//
template <>
template <typename VERTEX, typename MASK>
inline void
Scheme<SCHEME_LOOP>::assignCornerLimitMask(VERTEX const& /* vertex */, MASK& posMask) const {
posMask.SetNumVertexWeights(1);
posMask.SetNumEdgeWeights(0);
posMask.SetNumFaceWeights(0);
posMask.SetFaceWeightsForFaceCenters(false);
posMask.VertexWeight(0) = 1.0f;
}
template <>
template <typename VERTEX, typename MASK>
inline void
Scheme<SCHEME_LOOP>::assignCreaseLimitMask(VERTEX const& vertex, MASK& posMask,
int const creaseEnds[2]) const {
typedef typename MASK::Weight Weight;
int valence = vertex.GetNumEdges();
posMask.SetNumVertexWeights(1);
posMask.SetNumEdgeWeights(valence);
posMask.SetNumFaceWeights(0);
posMask.SetFaceWeightsForFaceCenters(false);
//
// The refinement mask for a crease vertex is (1/8, 3/4, 1/8) and for a crease
// edge is (1/2, 1/2) -- producing a uniform B-spline curve along the crease
// (boundary) whether the vertex or its crease is regular or not. The limit
// mask is therefore (1/6, 2/3, 1/6) for ALL cases.
//
// An alternative limit mask (1/5, 3/5, 1/5) is often published for use either
// for irregular crease vertices or for all crease/boundary vertices, but this
// is based on an alternate refinement mask for the edge -- (3/8, 5/8) versus
// the usual (1/2, 1/2) -- and will not produce the B-spline curve desired.
//
Weight vWeight = 4.0f / 6.0f;
Weight eWeight = 1.0f / 6.0f;
posMask.VertexWeight(0) = vWeight;
for (int i = 0; i < valence; ++i) {
posMask.EdgeWeight(i) = 0.0f;
}
posMask.EdgeWeight(creaseEnds[0]) = eWeight;
posMask.EdgeWeight(creaseEnds[1]) = eWeight;
}
template <>
template <typename VERTEX, typename MASK>
inline void
Scheme<SCHEME_LOOP>::assignSmoothLimitMask(VERTEX const& vertex, MASK& posMask) const {
typedef typename MASK::Weight Weight;
int valence = vertex.GetNumFaces();
assert(valence != 2);
posMask.SetNumVertexWeights(1);
posMask.SetNumEdgeWeights(valence);
posMask.SetNumFaceWeights(0);
posMask.SetFaceWeightsForFaceCenters(false);
// Specialize for the regular case: 1/12 per edge-vert, 1/2 for the vert itself:
if (valence == 6) {
Weight eWeight = 1.0f / 12.0f;
Weight vWeight = 0.5f;
posMask.VertexWeight(0) = vWeight;
posMask.EdgeWeight(0) = eWeight;
posMask.EdgeWeight(1) = eWeight;
posMask.EdgeWeight(2) = eWeight;
posMask.EdgeWeight(3) = eWeight;
posMask.EdgeWeight(4) = eWeight;
posMask.EdgeWeight(5) = eWeight;
} else {
Weight invValence = 1.0f / valence;
Weight beta = 0.25f * cosf((Weight)M_PI * 2.0f * invValence) + 0.375f;
beta = (0.625f - (beta * beta)) * invValence;;
Weight eWeight = 1.0f / (valence + 3.0f / (8.0f * beta));
Weight vWeight = (Weight)(1.0f - (eWeight * valence));
posMask.VertexWeight(0) = vWeight;
for (int i = 0; i < valence; ++i) {
posMask.EdgeWeight(i) = eWeight;
}
}
}
/*
// Limit masks for tangents:
//
// A note on tangent magnitudes:
//
// Several formulae exist for limit tangents at a vertex to accomodate the
// different topological configurations around the vertex. While these produce
// the desired direction, there is inconsistency in the resulting magnitudes.
// Ideally a regular mesh of uniformly shaped triangles with similar edge lengths
// should produce tangents of similar magnitudes throughout -- including corners
// and boundaries. So some of the common formulae for these are adjusted with
// scale factors.
//
// For uses where magnitude does not matter, this scaling should be irrelevant.
// But just as with patches, where the magnitudes of partial derivates are
// consistent between similar patches, the magnitudes of limit tangents should
// also be similar.
//
// The reference tangents, in terms of magnitudes, are those produced by the
// limit tangent mask for smooth interior vertices, for which well established
// sin/cos formulae apply -- these remain unscaled. Formulae for the other
// crease/boundary, corner tangents and irregular cases are scaled to be more
// consistent with these.
//
// The crease/boundary tangents for the regular case can be viewed as derived
// from the smooth interior masks with two "phantom" points extrapolated across
// the regular boundary:
//
// v3 v2
// X - - - - - X
// / \ / \
// / \ / \
// v4 X - - - - - X - - - - - X v1
// . . 0 . .
// . . . .
// . . . .
// (v5) (v6)
//
// where v5 = v0 + (v4 - v3) and v6 = v0 + v1 - v2.
//
// When the standard limit tangent mask is applied, the cosines of increments
// of pi/3 gives us coefficients that are mutliples of 1/2, leading to the first
// tangent T1 = 3/2 * (v1 - v4), rather than the widely used T1 = v1 - v4. So
// this scale factor of 3/2 is applied to insure tangents along the boundaries
// are of similar magnitude as tangents in the immediate interior (which may be
// parallel).
//
// Tangents at corners are essentially a form of boundary tangent, and so its
// simple difference formula is scaled to be consistent with adjoining boundary
// tangents -- not just with the 3/2 factor from above, but with an additional
// 2.0 to compensate for the fact that the difference of only side of the vertex
// is considered here. The resulting scale factor of 3.0 for the regular corner
// is what similarly arises by extrapolating an interior region around the
// vertex and using the interior mask for the first tangent.
//
// The cross-tangent formula for the regular crease/boundary is similarly found
// from the above construction of the boundary, but the commonly used weights of
// +/- 1 and 2 result from omitting the common factor of sqrt(3)/2 (arising from
// the sines of increments of pi/3). With that scale factor close to one, it has
// less impact than the irregular cases, which are analogous to corner tangents
// in that differences on only one side of the vertex are considered. While a
// scaling of 3.0 is similarly understandable for the valence 2 and 3 cases, it is
// less obvious in the irregular formula for valence > 4, but similarly effective.
//
// The end result of these adjustments should be a set of limit tangents that are
// of similar magnitude over a regular mesh including boundaries and corners.
*/
template <>
template <typename VERTEX, typename MASK>
inline void
Scheme<SCHEME_LOOP>::assignCornerLimitTangentMasks(VERTEX const& vertex,
MASK& tan1Mask, MASK& tan2Mask) const {
int valence = vertex.GetNumEdges();
tan1Mask.SetNumVertexWeights(1);
tan1Mask.SetNumEdgeWeights(valence);
tan1Mask.SetNumFaceWeights(0);
tan1Mask.SetFaceWeightsForFaceCenters(false);
tan2Mask.SetNumVertexWeights(1);
tan2Mask.SetNumEdgeWeights(valence);
tan2Mask.SetNumFaceWeights(0);
tan2Mask.SetFaceWeightsForFaceCenters(false);
// See note above regarding scale factor of 3.0:
tan1Mask.VertexWeight(0) = -3.0f;
tan1Mask.EdgeWeight(0) = 3.0f;
tan1Mask.EdgeWeight(1) = 0.0f;
tan2Mask.VertexWeight(0) = -3.0f;
tan2Mask.EdgeWeight(0) = 0.0f;
tan2Mask.EdgeWeight(1) = 3.0f;
// Should be at least 2 edges -- be sure to clear weights for any more:
for (int i = 2; i < valence; ++i) {
tan1Mask.EdgeWeight(i) = 0.0f;
tan2Mask.EdgeWeight(i) = 0.0f;
}
}
template <>
template <typename VERTEX, typename MASK>
inline void
Scheme<SCHEME_LOOP>::assignCreaseLimitTangentMasks(VERTEX const& vertex,
MASK& tan1Mask, MASK& tan2Mask, int const creaseEnds[2]) const {
typedef typename MASK::Weight Weight;
//
// First, the tangent along the crease:
// The first crease edge is considered the "leading" edge of the span
// of surface for which we are evaluating tangents and the second edge the
// "trailing edge". By convention, the tangent along the crease is oriented
// in the direction of the leading edge.
//
int valence = vertex.GetNumEdges();
tan1Mask.SetNumVertexWeights(1);
tan1Mask.SetNumEdgeWeights(valence);
tan1Mask.SetNumFaceWeights(0);
tan1Mask.SetFaceWeightsForFaceCenters(false);
tan1Mask.VertexWeight(0) = 0.0f;
for (int i = 0; i < valence; ++i) {
tan1Mask.EdgeWeight(i) = 0.0f;
}
// See the note above regarding scale factor of 1.5:
tan1Mask.EdgeWeight(creaseEnds[0]) = 1.5f;
tan1Mask.EdgeWeight(creaseEnds[1]) = -1.5f;
//
// Second, the tangent across the interior faces:
// Note this is ambigous for an interior vertex. We currently return
// the tangent for the surface in the counter-clockwise span between the
// leading and trailing edges that form the crease. Given the expected
// computation of a surface normal as Tan1 X Tan2, this tangent should be
// oriented "inward" from the crease/boundary -- across the surface rather
// than outward and away from it.
//
// There is inconsistency in the orientation of this tangent in commonly
// published results: the general formula provided for arbitrary valence
// has the tangent pointing across the crease and "outward" from the surface,
// while the special cases for regular valence and lower have the tangent
// pointing across the surface and "inward" from the crease. So if we are
// to consistently orient the first tangent along the crease, regardless of
// the interior topology, we have to correct this. With the first tangent
// following the direction of the leading crease edge, we want the second
// tangent pointing inward/across the surface -- so we flip the result of
// the general formula.
//
tan2Mask.SetNumVertexWeights(1);
tan2Mask.SetNumEdgeWeights(valence);
tan2Mask.SetNumFaceWeights(0);
tan2Mask.SetFaceWeightsForFaceCenters(false);
for (int i = 0; i < creaseEnds[0]; ++i) {
tan2Mask.EdgeWeight(i) = 0.0f;
}
int interiorEdgeCount = creaseEnds[1] - creaseEnds[0] - 1;
if (interiorEdgeCount == 2) {
// See note above regarding scale factor of (sin(60 degs) == sqrt(3)/2:
static Weight const Root3 = (Weight) 1.73205080756887729352f;
static Weight const Root3by2 = (Weight) (Root3 * 0.5);
tan2Mask.VertexWeight(0) = -Root3;
tan2Mask.EdgeWeight(creaseEnds[0]) = -Root3by2;
tan2Mask.EdgeWeight(creaseEnds[1]) = -Root3by2;
tan2Mask.EdgeWeight(creaseEnds[0] + 1) = Root3;
tan2Mask.EdgeWeight(creaseEnds[0] + 2) = Root3;
} else if (interiorEdgeCount > 2) {
// See notes above regarding scale factor of -3.0 (-1 for orientation,
// 2.0 for considering the region as a half-disk, and 1.5 in keeping
// with the crease tangent):
double theta = M_PI / (interiorEdgeCount + 1);
Weight cWeight = -3.0f * std::sin(theta);
Weight eWeightCoeff = -3.0f * (2.0f * std::cos(theta) - 2.0f);
tan2Mask.VertexWeight(0) = 0.0f;
tan2Mask.EdgeWeight(creaseEnds[0]) = cWeight;
tan2Mask.EdgeWeight(creaseEnds[1]) = cWeight;
for (int i = 1; i <= interiorEdgeCount; ++i) {
tan2Mask.EdgeWeight(creaseEnds[0] + i) = eWeightCoeff * std::sin(i * theta);
}
} else if (interiorEdgeCount == 1) {
// See notes above regarding scale factor of 3.0:
tan2Mask.VertexWeight(0) = -3.0f;
tan2Mask.EdgeWeight(creaseEnds[0]) = 0.0f;
tan2Mask.EdgeWeight(creaseEnds[1]) = 0.0f;
tan2Mask.EdgeWeight(creaseEnds[0] + 1) = 3.0f;
} else {
// See notes above regarding scale factor of 3.0:
tan2Mask.VertexWeight(0) = -6.0f;
tan2Mask.EdgeWeight(creaseEnds[0]) = 3.0f;
tan2Mask.EdgeWeight(creaseEnds[1]) = 3.0f;
}
for (int i = creaseEnds[1] + 1; i < valence; ++i) {
tan2Mask.EdgeWeight(i) = 0.0f;
}
}
template <>
template <typename VERTEX, typename MASK>
inline void
Scheme<SCHEME_LOOP>::assignSmoothLimitTangentMasks(VERTEX const& vertex,
MASK& tan1Mask, MASK& tan2Mask) const {
typedef typename MASK::Weight Weight;
int valence = vertex.GetNumFaces();
assert(valence != 2);
tan1Mask.SetNumVertexWeights(1);
tan1Mask.SetNumEdgeWeights(valence);
tan1Mask.SetNumFaceWeights(0);
tan1Mask.SetFaceWeightsForFaceCenters(false);
tan2Mask.SetNumVertexWeights(1);
tan2Mask.SetNumEdgeWeights(valence);
tan2Mask.SetNumFaceWeights(0);
tan2Mask.SetFaceWeightsForFaceCenters(false);
tan1Mask.VertexWeight(0) = 0.0f;
tan2Mask.VertexWeight(0) = 0.0f;
if (valence == 6) {
static Weight const Root3by2 = (Weight)(0.5f * 1.73205080756887729352f);
tan1Mask.EdgeWeight(0) = 1.0f;
tan1Mask.EdgeWeight(1) = 0.5f;
tan1Mask.EdgeWeight(2) = -0.5f;
tan1Mask.EdgeWeight(3) = -1.0f;
tan1Mask.EdgeWeight(4) = -0.5f;
tan1Mask.EdgeWeight(5) = 0.5f;
tan2Mask.EdgeWeight(0) = 0.0f;
tan2Mask.EdgeWeight(1) = Root3by2;
tan2Mask.EdgeWeight(2) = Root3by2;
tan2Mask.EdgeWeight(3) = 0.0f;
tan2Mask.EdgeWeight(4) = -Root3by2;
tan2Mask.EdgeWeight(5) = -Root3by2;
} else {
Weight alpha = (Weight) (2.0f * M_PI / valence);
for (int i = 0; i < valence; ++i) {
double alphaI = alpha * i;
tan1Mask.EdgeWeight(i) = std::cos(alphaI);
tan2Mask.EdgeWeight(i) = std::sin(alphaI);
}
}
}
} // end namespace Sdc
} // end namespace OPENSUBDIV_VERSION
using namespace OPENSUBDIV_VERSION;
} // end namespace OpenSubdiv
#endif /* OPENSUBDIV3_SDC_LOOP_SCHEME_H */
Reference in New Issue View Git Blame Copy Permalink