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USD -> SDF: polygon triangulation (#819)
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* polygon triangulation using the fan-triangulation algorithm

Signed-off-by: Teo Koon Peng <[email protected]>

* remove cgal dep

Signed-off-by: Teo Koon Peng <[email protected]>

* add todo

Signed-off-by: Teo Koon Peng <[email protected]>

* fix xformOp:transform parsing (#822)

Signed-off-by: Teo Koon Peng <[email protected]>

Co-authored-by: ahcorde <[email protected]>
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Teo Koon Peng and ahcorde authored Jan 18, 2022
1 parent 83f86ab commit aa1333d
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Showing 3 changed files with 45 additions and 154 deletions.
2 changes: 0 additions & 2 deletions src/CMakeLists.txt
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Expand Up @@ -96,7 +96,6 @@ else()
endif()

find_package(pxr REQUIRED)
find_package(CGAL)

include_directories(${PXR_INCLUDE_DIRS})
set(sources ${sources}
Expand Down Expand Up @@ -265,7 +264,6 @@ target_link_libraries(${sdf_target}
ignition-common${IGN_COMMON_VER}::graphics
${PYTHON_LIBRARY}
${PXR_LIBRARIES}
CGAL::CGAL
PRIVATE
${TinyXML2_LIBRARIES})

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84 changes: 24 additions & 60 deletions src/usd/usd_parser/polygon_helper.cc
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Expand Up @@ -17,77 +17,41 @@

#include "polygon_helper.hh"

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Delaunay_triangulation_3.h>
#include <CGAL/Triangulation_vertex_base_with_info_3.h>
#include <CGAL/Random.h>
#include <vector>
#include <cassert>

typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Triangulation_vertex_base_with_info_3<unsigned int, K> Vb;
typedef CGAL::Delaunay_triangulation_cell_base_3<K> Cb;
typedef CGAL::Triangulation_data_structure_3<Vb, Cb> Tds;
typedef CGAL::Delaunay_triangulation_3<K, Tds> Delaunay;
typedef Delaunay::Point Point;

namespace usd
{
std::vector<unsigned int> PolygonToTriangles(
pxr::VtIntArray &_faceVertexIndices,
pxr::VtIntArray &_faceVertexCounts,
pxr::VtArray<pxr::GfVec3f> &_points)
pxr::VtIntArray &_faceVertexIndices,
pxr::VtIntArray &_faceVertexCounts,
pxr::VtArray<pxr::GfVec3f> &_points)
{
std::vector<unsigned int> indices;
// TODO: Use more robust algorithms.
// For reference, blender supports "ear-clipping", and "Beauty".
// ref: https://blender.stackexchange.com/questions/215553/what-algorithm-is-used-for-beauty-triangulation
// ref: https://en.wikipedia.org/wiki/Polygon_triangulation
size_t count = 0;
for (const auto &vCount : _faceVertexCounts)
{
count += vCount - 2;
}
std::vector<unsigned int> triangles;
triangles.reserve(count * 3);

unsigned int indexVertex = 0;
for (unsigned int i = 0; i < _faceVertexCounts.size(); ++i)
size_t cur = 0;
for (const auto &vCount : _faceVertexCounts)
{
if (_faceVertexCounts[i] == 3)
{
unsigned int j = indexVertex;
unsigned int indexVertexStop = indexVertex + 3;
for (; j < indexVertexStop; ++j)
{
indices.emplace_back(_faceVertexIndices[j]);
++indexVertex;
}
}
else
for (size_t i = cur + 2; i < cur + vCount; i++)
{
std::vector< std::pair<Point, unsigned> > P;
for (int j = 0; j < _faceVertexCounts[i]; ++j)
{
pxr::GfVec3f & _p = _points[_faceVertexIndices[indexVertex]];
P.push_back(
std::make_pair(
Point(_p[0], _p[1], _p[2]),
_faceVertexIndices[indexVertex]));
++indexVertex;
}
Delaunay triangulation(P.begin(), P.end());

bool goodTriangle = true;
for(Delaunay::Finite_facets_iterator fit = triangulation.finite_facets_begin();
fit != triangulation.finite_facets_end(); ++fit)
{
auto &face = fit;
goodTriangle = false;
}

if (goodTriangle)
{
for(Delaunay::Finite_facets_iterator fit = triangulation.finite_facets_begin();
fit != triangulation.finite_facets_end(); ++fit)
{
auto &face = fit;
indices.emplace_back(face->first->vertex(0)->info());
indices.emplace_back(face->first->vertex(1)->info());
indices.emplace_back(face->first->vertex(2)->info());
}
}
triangles.emplace_back(_faceVertexIndices[cur]);
triangles.emplace_back(_faceVertexIndices[i - 1]);
triangles.emplace_back(_faceVertexIndices[i]);
}
cur += vCount;
}
return indices;
assert(triangles.size() == count * 3);

return triangles;
}
}
113 changes: 21 additions & 92 deletions src/usd/usd_parser/utils.cc
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Expand Up @@ -359,6 +359,12 @@ namespace usd
}

pose.Pos() = t.translate * metersPerUnit;
// scaling is lost when we convert to pose, so we pre-scale the translation
// to make them match the scaled values.
if (!_tfs.empty()) {
auto& child = _tfs.back();
child.Pos().Set(child.Pos().X() * t.scale[0], child.Pos().Y() * t.scale[1], child.Pos().Z() * t.scale[2]);
}

if (!t.isRotationZYX)
{
Expand Down Expand Up @@ -560,105 +566,28 @@ namespace usd

if (op == "xformOp:transform")
{
// FIXME: Shear is lost (does sdformat support it?).

pxr::GfMatrix4d transform;
_prim.GetAttribute(pxr::TfToken("xformOp:transform")).Get(&transform);
pxr::GfVec3d translateMatrix = transform.ExtractTranslation();
pxr::GfQuatd rotation_quadMatrix = transform.ExtractRotationQuat();

ignition::math::Matrix4d m(
transform[0][0], transform[0][1], transform[0][2], transform[0][3],
transform[1][0], transform[1][1], transform[1][2], transform[1][3],
transform[2][0], transform[2][1], transform[2][2], transform[2][3],
transform[3][0], transform[3][1], transform[3][2], transform[3][3]
);
std::cerr << "m " << m << '\n';
const auto rot = transform.RemoveScaleShear();
const auto scaleShear = transform * rot.GetInverse();

std::pair<std::string, std::shared_ptr<USDStage>> data =
_usdData.findStage(_prim.GetPath().GetName());
t.scale[0] = scaleShear[0][0];
t.scale[1] = scaleShear[1][1];
t.scale[2] = scaleShear[2][2];

// bool upAxisZ = (data.second->_upAxis == "Z");
// if(!upAxisZ)
// {
// ignition::math::Matrix4d mUpAxis(
// 1, 0, 0, 0,
// 0, 0, -1, 0,
// 0, 1, 0, 0,
// 0, 0, 0, 1);
//
// pxr::GfMatrix4d mUpAxis2(
// 1, 0, 0, 0,
// 0, 0, -1, 0,
// 0, 1, 0, 0,
// 0, 0, 0, 1);
//
// m = mUpAxis * m;
// transform = mUpAxis2 * transform;
// std::cerr << "m upAxis " << m << '\n';
// }

ignition::math::Vector3d eulerAngles = m.EulerRotation(true);
std::cerr << "eulerAngles " << eulerAngles << '\n';
ignition::math::Matrix4d inverseRX(ignition::math::Pose3d(
ignition::math::Vector3d(0, 0, 0),
ignition::math::Quaterniond(-eulerAngles[0], 0, 0)));
ignition::math::Matrix4d inverseRY(ignition::math::Pose3d(
ignition::math::Vector3d(0, 0, 0),
ignition::math::Quaterniond(0, -eulerAngles[1], 0)));
ignition::math::Matrix4d inverseRZ(ignition::math::Pose3d(
ignition::math::Vector3d(0, 0, 0),
ignition::math::Quaterniond(0, 0, -eulerAngles[2])));

pxr::GfMatrix4d inverseR2X(
inverseRX(0, 0), inverseRX(0, 1), inverseRX(0, 2), inverseRX(0, 3),
inverseRX(1, 0), inverseRX(1, 1), inverseRX(1, 2), inverseRX(1, 3),
inverseRX(2, 0), inverseRX(2, 1), inverseRX(2, 2), inverseRX(2, 3),
inverseRX(3, 0), inverseRX(3, 1), inverseRX(3, 2), inverseRX(3, 3));
pxr::GfMatrix4d inverseR2Y(
inverseRY(0, 0), inverseRY(0, 1), inverseRY(0, 2), inverseRY(0, 3),
inverseRY(1, 0), inverseRY(1, 1), inverseRY(1, 2), inverseRY(1, 3),
inverseRY(2, 0), inverseRY(2, 1), inverseRY(2, 2), inverseRY(2, 3),
inverseRY(3, 0), inverseRY(3, 1), inverseRY(3, 2), inverseRY(3, 3));
pxr::GfMatrix4d inverseR2Z(
inverseRZ(0, 0), inverseRZ(0, 1), inverseRZ(0, 2), inverseRZ(0, 3),
inverseRZ(1, 0), inverseRZ(1, 1), inverseRZ(1, 2), inverseRZ(1, 3),
inverseRZ(2, 0), inverseRZ(2, 1), inverseRZ(2, 2), inverseRZ(2, 3),
inverseRZ(3, 0), inverseRZ(3, 1), inverseRZ(3, 2), inverseRZ(3, 3));

m = inverseRX * (inverseRY * (inverseRZ * m));
transform = inverseR2X * (inverseR2Y * (inverseR2Z * transform));
// ignition::math::Vector3d t = m.Translation();
// ignition::math::Vector3d euler = m.EulerRotation(true);
// ignition::math::Quaternion r(eulerAngles[0], eulerAngles[1], eulerAngles[2]);
std::cerr << "m " << m << '\n';

// std::cerr << "m " << m << '\n';
// std::cerr << "transform " << transform << '\n';

t.scale[0] = transform[0][0];
t.scale[1] = transform[1][1];
t.scale[2] = transform[2][2];

pxr::GfVec3d translateVector = transform.ExtractTranslation();
pxr::GfQuatd rotationInversed = transform.ExtractRotationQuat();
t.translate = ignition::math::Vector3d(
translateVector[0], translateVector[1], translateVector[2]);
ignition::math::Quaterniond q(eulerAngles[0], eulerAngles[1], eulerAngles[2]);
const auto rotQuat = rot.ExtractRotationQuat();
t.translate = ignition::math::Vector3d(transform[3][0], transform[3][1], transform[3][2]);
ignition::math::Quaterniond q(
rotQuat.GetReal(),
rotQuat.GetImaginary()[0],
rotQuat.GetImaginary()[1],
rotQuat.GetImaginary()[2]
);
t.q.push_back(q);
// translate[0] = translateVector[0];
// translate[1] = translateVector[1];
// translate[2] = translateVector[2];
// rotationQuad.SetImaginary(r.X(), r.Y(), r.Z());
// rotationQuad.SetReal(r.W());

// isTranslate = true;
// isRotation = true;
// isScale = true;
t.isTranslate = true;
t.isRotation = true;

std::cerr << "translate " << t.translate << '\n';
std::cerr << "rotation_quad " << q << '\n';
std::cerr << "scale " << t.scale << '\n';
}
}
return t;
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