restructure more
This commit is contained in:
Ben Kyd
507
ThirdParty/assimp/code/PostProcessing/TriangulateProcess.cpp
vendored
Normal file
507
ThirdParty/assimp/code/PostProcessing/TriangulateProcess.cpp
vendored
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@@ -0,0 +1,507 @@
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/*
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---------------------------------------------------------------------------
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Open Asset Import Library (assimp)
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---------------------------------------------------------------------------
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Copyright (c) 2006-2025, assimp team
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|
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All rights reserved.
|
||||
|
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Redistribution and use of this software in source and binary forms,
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||||
with or without modification, are permitted provided that the following
|
||||
conditions are met:
|
||||
|
||||
* Redistributions of source code must retain the above
|
||||
copyright notice, this list of conditions and the
|
||||
following disclaimer.
|
||||
|
||||
* Redistributions in binary form must reproduce the above
|
||||
copyright notice, this list of conditions and the
|
||||
following disclaimer in the documentation and/or other
|
||||
materials provided with the distribution.
|
||||
|
||||
* Neither the name of the assimp team, nor the names of its
|
||||
contributors may be used to endorse or promote products
|
||||
derived from this software without specific prior
|
||||
written permission of the assimp team.
|
||||
|
||||
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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||||
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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---------------------------------------------------------------------------
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*/
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/** @file TriangulateProcess.cpp
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* @brief Implementation of the post processing step to split up
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* all faces with more than three indices into triangles.
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*
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*
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* The triangulation algorithm will handle concave or convex polygons.
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* Self-intersecting or non-planar polygons are not rejected, but
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* they're probably not triangulated correctly.
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*
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* DEBUG SWITCHES - do not enable any of them in release builds:
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*
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* AI_BUILD_TRIANGULATE_COLOR_FACE_WINDING
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* - generates vertex colors to represent the face winding order.
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* the first vertex of a polygon becomes red, the last blue.
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* AI_BUILD_TRIANGULATE_DEBUG_POLYS
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* - dump all polygons and their triangulation sequences to
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* a file
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*/
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#ifndef ASSIMP_BUILD_NO_TRIANGULATE_PROCESS
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#include "PostProcessing/TriangulateProcess.h"
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#include "PostProcessing/ProcessHelper.h"
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#include "Common/PolyTools.h"
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#include "contrib/earcut-hpp/earcut.hpp"
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#include <memory>
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#include <cstdint>
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//#define AI_BUILD_TRIANGULATE_COLOR_FACE_WINDING
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//#define AI_BUILD_TRIANGULATE_DEBUG_POLYS
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#define POLY_GRID_Y 40
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#define POLY_GRID_X 70
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#define POLY_GRID_XPAD 20
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#define POLY_OUTPUT_FILE "assimp_polygons_debug.txt"
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namespace mapbox::util {
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template <>
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struct nth<0, aiVector2D> {
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inline static auto get(const aiVector2D& t) {
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return t.x;
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}
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};
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template <>
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struct nth<1, aiVector2D> {
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inline static auto get(const aiVector2D& t) {
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return t.y;
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}
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};
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} // namespace mapbox::util
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using namespace Assimp;
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namespace {
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/**
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* @brief Helper struct used to simplify NGON encoding functions.
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*/
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struct NGONEncoder {
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NGONEncoder() : mLastNGONFirstIndex((unsigned int)-1) {}
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/**
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* @brief Encode the current triangle, and make sure it is recognized as a triangle.
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*
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* This method will rotate indices in tri if needed in order to avoid tri to be considered
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* part of the previous ngon. This method is to be used whenever you want to emit a real triangle,
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* and make sure it is seen as a triangle.
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*
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* @param tri Triangle to encode.
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*/
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void ngonEncodeTriangle(aiFace * tri) {
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ai_assert(tri->mNumIndices == 3);
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// Rotate indices in new triangle to avoid ngon encoding false ngons
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// Otherwise, the new triangle would be considered part of the previous NGON.
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if (isConsideredSameAsLastNgon(tri)) {
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std::swap(tri->mIndices[0], tri->mIndices[2]);
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std::swap(tri->mIndices[1], tri->mIndices[2]);
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}
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mLastNGONFirstIndex = tri->mIndices[0];
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}
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/**
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* @brief Encode a quad (2 triangles) in ngon encoding, and make sure they are seen as a single ngon.
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*
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* @param tri1 First quad triangle
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* @param tri2 Second quad triangle
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*
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* @pre Triangles must be properly fanned from the most appropriate vertex.
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*/
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void ngonEncodeQuad(aiFace *tri1, aiFace *tri2) {
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ai_assert(tri1->mNumIndices == 3);
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ai_assert(tri2->mNumIndices == 3);
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ai_assert(tri1->mIndices[0] == tri2->mIndices[0]);
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// If the selected fanning vertex is the same as the previously
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// emitted ngon, we use the opposite vertex which also happens to work
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// for tri-fanning a concave quad.
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// ref: https://github.com/assimp/assimp/pull/3695#issuecomment-805999760
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if (isConsideredSameAsLastNgon(tri1)) {
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// Right-rotate indices for tri1 (index 2 becomes the new fanning vertex)
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std::swap(tri1->mIndices[0], tri1->mIndices[2]);
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std::swap(tri1->mIndices[1], tri1->mIndices[2]);
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// Left-rotate indices for tri2 (index 2 becomes the new fanning vertex)
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std::swap(tri2->mIndices[1], tri2->mIndices[2]);
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std::swap(tri2->mIndices[0], tri2->mIndices[2]);
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ai_assert(tri1->mIndices[0] == tri2->mIndices[0]);
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}
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mLastNGONFirstIndex = tri1->mIndices[0];
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}
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/**
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* @brief Check whether this triangle would be considered part of the lastly emitted ngon or not.
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*
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* @param tri Current triangle.
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* @return true If used as is, this triangle will be part of last ngon.
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* @return false If used as is, this triangle is not considered part of the last ngon.
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*/
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bool isConsideredSameAsLastNgon(const aiFace * tri) const {
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ai_assert(tri->mNumIndices == 3);
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return tri->mIndices[0] == mLastNGONFirstIndex;
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}
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private:
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unsigned int mLastNGONFirstIndex;
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};
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}
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// ------------------------------------------------------------------------------------------------
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// Returns whether the processing step is present in the given flag field.
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bool TriangulateProcess::IsActive( unsigned int pFlags) const {
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return (pFlags & aiProcess_Triangulate) != 0;
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}
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// ------------------------------------------------------------------------------------------------
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// Executes the post processing step on the given imported data.
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void TriangulateProcess::Execute( aiScene* pScene) {
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ASSIMP_LOG_DEBUG("TriangulateProcess begin");
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bool bHas = false;
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for( unsigned int a = 0; a < pScene->mNumMeshes; a++)
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{
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if (pScene->mMeshes[ a ]) {
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if ( TriangulateMesh( pScene->mMeshes[ a ] ) ) {
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bHas = true;
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}
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}
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}
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if ( bHas ) {
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ASSIMP_LOG_INFO( "TriangulateProcess finished. All polygons have been triangulated." );
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} else {
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ASSIMP_LOG_DEBUG( "TriangulateProcess finished. There was nothing to be done." );
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}
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}
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// ------------------------------------------------------------------------------------------------
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// Triangulates the given mesh.
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bool TriangulateProcess::TriangulateMesh( aiMesh* pMesh) {
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// Now we have aiMesh::mPrimitiveTypes, so this is only here for test cases
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if (!pMesh->mPrimitiveTypes) {
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bool bNeed = false;
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for( unsigned int a = 0; a < pMesh->mNumFaces; a++) {
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const aiFace& face = pMesh->mFaces[a];
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if( face.mNumIndices != 3) {
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bNeed = true;
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}
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}
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if (!bNeed) {
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return false;
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}
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}
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else if (!(pMesh->mPrimitiveTypes & aiPrimitiveType_POLYGON)) {
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return false;
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}
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// Find out how many output faces we'll get
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uint32_t numOut = 0, max_out = 0;
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bool get_normals = true;
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for( unsigned int a = 0; a < pMesh->mNumFaces; a++) {
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aiFace& face = pMesh->mFaces[a];
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if (face.mNumIndices <= 4) {
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get_normals = false;
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}
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if( face.mNumIndices <= 3) {
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++numOut;
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} else {
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numOut += face.mNumIndices-2;
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max_out = std::max(max_out,face.mNumIndices);
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}
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}
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// Just another check whether aiMesh::mPrimitiveTypes is correct
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if (numOut == pMesh->mNumFaces) {
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ASSIMP_LOG_ERROR( "Invalidation detected in the number of indices: does not fit to the primitive type." );
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return false;
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}
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aiVector3D *nor_out = nullptr;
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// if we don't have normals yet, but expect them to be a cheap side
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// product of triangulation anyway, allocate storage for them.
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if (!pMesh->mNormals && get_normals) {
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// XXX need a mechanism to inform the GenVertexNormals process to treat these normals as preprocessed per-face normals
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// nor_out = pMesh->mNormals = new aiVector3D[pMesh->mNumVertices];
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}
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// the output mesh will contain triangles, but no polys anymore
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pMesh->mPrimitiveTypes |= aiPrimitiveType_TRIANGLE;
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pMesh->mPrimitiveTypes &= ~aiPrimitiveType_POLYGON;
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// The mesh becomes NGON encoded now, during the triangulation process.
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pMesh->mPrimitiveTypes |= aiPrimitiveType_NGONEncodingFlag;
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aiFace* out = new aiFace[numOut](), *curOut = out;
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std::vector<aiVector3D> temp_verts3d(max_out+2); /* temporary storage for vertices */
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std::vector<std::vector<aiVector2D>> temp_poly(1); /* temporary storage for earcut.hpp */
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std::vector<aiVector2D>& temp_verts = temp_poly[0];
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temp_verts.reserve(max_out + 2);
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NGONEncoder ngonEncoder;
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// Apply vertex colors to represent the face winding?
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#ifdef AI_BUILD_TRIANGULATE_COLOR_FACE_WINDING
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if (!pMesh->mColors[0])
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pMesh->mColors[0] = new aiColor4D[pMesh->mNumVertices];
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else
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new(pMesh->mColors[0]) aiColor4D[pMesh->mNumVertices];
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aiColor4D* clr = pMesh->mColors[0];
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#endif
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#ifdef AI_BUILD_TRIANGULATE_DEBUG_POLYS
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FILE* fout = fopen(POLY_OUTPUT_FILE,"a");
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#endif
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const aiVector3D* verts = pMesh->mVertices;
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for( unsigned int a = 0; a < pMesh->mNumFaces; a++) {
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aiFace& face = pMesh->mFaces[a];
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unsigned int* idx = face.mIndices;
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unsigned int num = face.mNumIndices;
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|
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// Apply vertex colors to represent the face winding?
|
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#ifdef AI_BUILD_TRIANGULATE_COLOR_FACE_WINDING
|
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for (unsigned int i = 0; i < face.mNumIndices; ++i) {
|
||||
aiColor4D& c = clr[idx[i]];
|
||||
c.r = (i+1) / (float)max;
|
||||
c.b = 1.f - c.r;
|
||||
}
|
||||
#endif
|
||||
|
||||
aiFace* const last_face = curOut;
|
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|
||||
// if it's a simple point,line or triangle: just copy it
|
||||
if( face.mNumIndices <= 3)
|
||||
{
|
||||
aiFace& nface = *curOut++;
|
||||
nface.mNumIndices = face.mNumIndices;
|
||||
nface.mIndices = face.mIndices;
|
||||
face.mIndices = nullptr;
|
||||
|
||||
// points and lines don't require ngon encoding (and are not supported either!)
|
||||
if (nface.mNumIndices == 3) ngonEncoder.ngonEncodeTriangle(&nface);
|
||||
|
||||
continue;
|
||||
}
|
||||
// optimized code for quadrilaterals
|
||||
else if ( face.mNumIndices == 4) {
|
||||
|
||||
// quads can have at maximum one concave vertex. Determine
|
||||
// this vertex (if it exists) and start tri-fanning from
|
||||
// it.
|
||||
unsigned int start_vertex = 0;
|
||||
for (unsigned int i = 0; i < 4; ++i) {
|
||||
const aiVector3D& v0 = verts[face.mIndices[(i+3) % 4]];
|
||||
const aiVector3D& v1 = verts[face.mIndices[(i+2) % 4]];
|
||||
const aiVector3D& v2 = verts[face.mIndices[(i+1) % 4]];
|
||||
|
||||
const aiVector3D& v = verts[face.mIndices[i]];
|
||||
|
||||
aiVector3D left = (v0-v);
|
||||
aiVector3D diag = (v1-v);
|
||||
aiVector3D right = (v2-v);
|
||||
|
||||
left.Normalize();
|
||||
diag.Normalize();
|
||||
right.Normalize();
|
||||
|
||||
const float angle = std::acos(left*diag) + std::acos(right*diag);
|
||||
if (angle > AI_MATH_PI_F) {
|
||||
// this is the concave point
|
||||
start_vertex = i;
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
const unsigned int temp[] = {face.mIndices[0], face.mIndices[1], face.mIndices[2], face.mIndices[3]};
|
||||
|
||||
aiFace& nface = *curOut++;
|
||||
nface.mNumIndices = 3;
|
||||
nface.mIndices = face.mIndices;
|
||||
|
||||
nface.mIndices[0] = temp[start_vertex];
|
||||
nface.mIndices[1] = temp[(start_vertex + 1) % 4];
|
||||
nface.mIndices[2] = temp[(start_vertex + 2) % 4];
|
||||
|
||||
aiFace& sface = *curOut++;
|
||||
sface.mNumIndices = 3;
|
||||
sface.mIndices = new unsigned int[3];
|
||||
|
||||
sface.mIndices[0] = temp[start_vertex];
|
||||
sface.mIndices[1] = temp[(start_vertex + 2) % 4];
|
||||
sface.mIndices[2] = temp[(start_vertex + 3) % 4];
|
||||
|
||||
// prevent double deletion of the indices field
|
||||
face.mIndices = nullptr;
|
||||
|
||||
ngonEncoder.ngonEncodeQuad(&nface, &sface);
|
||||
|
||||
continue;
|
||||
}
|
||||
else
|
||||
{
|
||||
// A polygon with more than 3 vertices can be either concave or convex.
|
||||
// Usually everything we're getting is convex and we could easily
|
||||
// triangulate by tri-fanning. However, LightWave is probably the only
|
||||
// modeling suite to make extensive use of highly concave, monster polygons ...
|
||||
// so we need to apply the full 'ear cutting' algorithm to get it right.
|
||||
|
||||
// REQUIREMENT: polygon is expected to be simple and *nearly* planar.
|
||||
// We project it onto a plane to get a 2d triangle.
|
||||
|
||||
// Collect all vertices of of the polygon.
|
||||
for (unsigned int tmp = 0; tmp < num; ++tmp) {
|
||||
temp_verts3d[tmp] = verts[idx[tmp]];
|
||||
}
|
||||
|
||||
// Get newell normal of the polygon. Store it for future use if it's a polygon-only mesh
|
||||
aiVector3D n;
|
||||
NewellNormal<3, 3, 3>(n, num, &temp_verts3d.front().x, &temp_verts3d.front().y, &temp_verts3d.front().z);
|
||||
if (nor_out) {
|
||||
for (unsigned int tmp = 0; tmp < num; ++tmp)
|
||||
nor_out[idx[tmp]] = n;
|
||||
}
|
||||
|
||||
// Select largest normal coordinate to ignore for projection
|
||||
const float ax = (n.x>0 ? n.x : -n.x);
|
||||
const float ay = (n.y>0 ? n.y : -n.y);
|
||||
const float az = (n.z>0 ? n.z : -n.z);
|
||||
|
||||
unsigned int ac = 0, bc = 1; /* no z coord. projection to xy */
|
||||
float inv = n.z;
|
||||
if (ax > ay) {
|
||||
if (ax > az) { /* no x coord. projection to yz */
|
||||
ac = 1; bc = 2;
|
||||
inv = n.x;
|
||||
}
|
||||
}
|
||||
else if (ay > az) { /* no y coord. projection to zy */
|
||||
ac = 2; bc = 0;
|
||||
inv = n.y;
|
||||
}
|
||||
|
||||
// Swap projection axes to take the negated projection vector into account
|
||||
if (inv < 0.f) {
|
||||
std::swap(ac,bc);
|
||||
}
|
||||
|
||||
temp_verts.resize(num);
|
||||
for (unsigned int tmp = 0; tmp < num; ++tmp) {
|
||||
temp_verts[tmp].x = verts[idx[tmp]][ac];
|
||||
temp_verts[tmp].y = verts[idx[tmp]][bc];
|
||||
}
|
||||
|
||||
auto indices = mapbox::earcut(temp_poly);
|
||||
for (size_t i = 0; i < indices.size(); i += 3) {
|
||||
aiFace& nface = *curOut++;
|
||||
nface.mIndices = new unsigned int[3];
|
||||
nface.mNumIndices = 3;
|
||||
nface.mIndices[0] = indices[i];
|
||||
nface.mIndices[1] = indices[i + 1];
|
||||
nface.mIndices[2] = indices[i + 2];
|
||||
}
|
||||
|
||||
#ifdef AI_BUILD_TRIANGULATE_DEBUG_POLYS
|
||||
// plot the plane onto which we mapped the polygon to a 2D ASCII pic
|
||||
aiVector2D bmin,bmax;
|
||||
ArrayBounds(&temp_verts[0],max,bmin,bmax);
|
||||
|
||||
char grid[POLY_GRID_Y][POLY_GRID_X+POLY_GRID_XPAD];
|
||||
std::fill_n((char*)grid,POLY_GRID_Y*(POLY_GRID_X+POLY_GRID_XPAD),' ');
|
||||
|
||||
for (int i =0; i < max; ++i) {
|
||||
const aiVector2D& v = (temp_verts[i] - bmin) / (bmax-bmin);
|
||||
const size_t x = static_cast<size_t>(v.x*(POLY_GRID_X-1)), y = static_cast<size_t>(v.y*(POLY_GRID_Y-1));
|
||||
char* loc = grid[y]+x;
|
||||
if (grid[y][x] != ' ') {
|
||||
for(;*loc != ' '; ++loc);
|
||||
*loc++ = '_';
|
||||
}
|
||||
*(loc+::ai_snprintf(loc, POLY_GRID_XPAD,"%i",i)) = ' ';
|
||||
}
|
||||
|
||||
|
||||
for(size_t y = 0; y < POLY_GRID_Y; ++y) {
|
||||
grid[y][POLY_GRID_X+POLY_GRID_XPAD-1] = '\0';
|
||||
fprintf(fout,"%s\n",grid[y]);
|
||||
}
|
||||
|
||||
fprintf(fout,"\ntriangulation sequence: ");
|
||||
#endif
|
||||
}
|
||||
|
||||
#ifdef AI_BUILD_TRIANGULATE_DEBUG_POLYS
|
||||
|
||||
for(aiFace* f = last_face; f != curOut; ++f) {
|
||||
unsigned int* i = f->mIndices;
|
||||
fprintf(fout," (%i %i %i)",i[0],i[1],i[2]);
|
||||
}
|
||||
|
||||
fprintf(fout,"\n*********************************************************************\n");
|
||||
fflush(fout);
|
||||
|
||||
#endif
|
||||
|
||||
for(aiFace* f = last_face; f != curOut; ) {
|
||||
unsigned int* i = f->mIndices;
|
||||
|
||||
i[0] = idx[i[0]];
|
||||
i[1] = idx[i[1]];
|
||||
i[2] = idx[i[2]];
|
||||
|
||||
// IMPROVEMENT: Polygons are not supported yet by this ngon encoding + triangulation step.
|
||||
// So we encode polygons as regular triangles. No way to reconstruct the original
|
||||
// polygon in this case.
|
||||
ngonEncoder.ngonEncodeTriangle(f);
|
||||
++f;
|
||||
}
|
||||
|
||||
delete[] face.mIndices;
|
||||
face.mIndices = nullptr;
|
||||
}
|
||||
|
||||
#ifdef AI_BUILD_TRIANGULATE_DEBUG_POLYS
|
||||
fclose(fout);
|
||||
#endif
|
||||
|
||||
// kill the old faces
|
||||
delete [] pMesh->mFaces;
|
||||
|
||||
// ... and store the new ones
|
||||
pMesh->mFaces = out;
|
||||
pMesh->mNumFaces = (unsigned int)(curOut-out); /* not necessarily equal to numOut */
|
||||
return true;
|
||||
}
|
||||
|
||||
#endif // !! ASSIMP_BUILD_NO_TRIANGULATE_PROCESS
|
||||
Reference in New Issue
Block a user