531 lines
19 KiB
C++
531 lines
19 KiB
C++
/*
|
|
---------------------------------------------------------------------------
|
|
Open Asset Import Library (assimp)
|
|
---------------------------------------------------------------------------
|
|
|
|
Copyright (c) 2006-2020, assimp team
|
|
|
|
All rights reserved.
|
|
|
|
Redistribution and use of this software in source and binary forms,
|
|
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
|
|
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
---------------------------------------------------------------------------
|
|
*/
|
|
|
|
/** @file TriangulateProcess.cpp
|
|
* @brief Implementation of the post processing step to split up
|
|
* all faces with more than three indices into triangles.
|
|
*
|
|
*
|
|
* The triangulation algorithm will handle concave or convex polygons.
|
|
* Self-intersecting or non-planar polygons are not rejected, but
|
|
* they're probably not triangulated correctly.
|
|
*
|
|
* DEBUG SWITCHES - do not enable any of them in release builds:
|
|
*
|
|
* AI_BUILD_TRIANGULATE_COLOR_FACE_WINDING
|
|
* - generates vertex colors to represent the face winding order.
|
|
* the first vertex of a polygon becomes red, the last blue.
|
|
* AI_BUILD_TRIANGULATE_DEBUG_POLYS
|
|
* - dump all polygons and their triangulation sequences to
|
|
* a file
|
|
*/
|
|
#ifndef ASSIMP_BUILD_NO_TRIANGULATE_PROCESS
|
|
|
|
#include "PostProcessing/TriangulateProcess.h"
|
|
#include "PostProcessing/ProcessHelper.h"
|
|
#include "Common/PolyTools.h"
|
|
|
|
#include <memory>
|
|
|
|
//#define AI_BUILD_TRIANGULATE_COLOR_FACE_WINDING
|
|
//#define AI_BUILD_TRIANGULATE_DEBUG_POLYS
|
|
|
|
#define POLY_GRID_Y 40
|
|
#define POLY_GRID_X 70
|
|
#define POLY_GRID_XPAD 20
|
|
#define POLY_OUTPUT_FILE "assimp_polygons_debug.txt"
|
|
|
|
using namespace Assimp;
|
|
|
|
// ------------------------------------------------------------------------------------------------
|
|
// Constructor to be privately used by Importer
|
|
TriangulateProcess::TriangulateProcess()
|
|
{
|
|
// nothing to do here
|
|
}
|
|
|
|
// ------------------------------------------------------------------------------------------------
|
|
// Destructor, private as well
|
|
TriangulateProcess::~TriangulateProcess()
|
|
{
|
|
// nothing to do here
|
|
}
|
|
|
|
// ------------------------------------------------------------------------------------------------
|
|
// Returns whether the processing step is present in the given flag field.
|
|
bool TriangulateProcess::IsActive( unsigned int pFlags) const
|
|
{
|
|
return (pFlags & aiProcess_Triangulate) != 0;
|
|
}
|
|
|
|
// ------------------------------------------------------------------------------------------------
|
|
// Executes the post processing step on the given imported data.
|
|
void TriangulateProcess::Execute( aiScene* pScene)
|
|
{
|
|
ASSIMP_LOG_DEBUG("TriangulateProcess begin");
|
|
|
|
bool bHas = false;
|
|
for( unsigned int a = 0; a < pScene->mNumMeshes; a++)
|
|
{
|
|
if (pScene->mMeshes[ a ]) {
|
|
if ( TriangulateMesh( pScene->mMeshes[ a ] ) ) {
|
|
bHas = true;
|
|
}
|
|
}
|
|
}
|
|
if ( bHas ) {
|
|
ASSIMP_LOG_INFO( "TriangulateProcess finished. All polygons have been triangulated." );
|
|
} else {
|
|
ASSIMP_LOG_DEBUG( "TriangulateProcess finished. There was nothing to be done." );
|
|
}
|
|
}
|
|
|
|
// ------------------------------------------------------------------------------------------------
|
|
// Triangulates the given mesh.
|
|
bool TriangulateProcess::TriangulateMesh( aiMesh* pMesh)
|
|
{
|
|
// Now we have aiMesh::mPrimitiveTypes, so this is only here for test cases
|
|
if (!pMesh->mPrimitiveTypes) {
|
|
bool bNeed = false;
|
|
|
|
for( unsigned int a = 0; a < pMesh->mNumFaces; a++) {
|
|
const aiFace& face = pMesh->mFaces[a];
|
|
|
|
if( face.mNumIndices != 3) {
|
|
bNeed = true;
|
|
}
|
|
}
|
|
if (!bNeed)
|
|
return false;
|
|
}
|
|
else if (!(pMesh->mPrimitiveTypes & aiPrimitiveType_POLYGON)) {
|
|
return false;
|
|
}
|
|
|
|
// Find out how many output faces we'll get
|
|
unsigned int numOut = 0, max_out = 0;
|
|
bool get_normals = true;
|
|
for( unsigned int a = 0; a < pMesh->mNumFaces; a++) {
|
|
aiFace& face = pMesh->mFaces[a];
|
|
if (face.mNumIndices <= 4) {
|
|
get_normals = false;
|
|
}
|
|
if( face.mNumIndices <= 3) {
|
|
numOut++;
|
|
|
|
}
|
|
else {
|
|
numOut += face.mNumIndices-2;
|
|
max_out = std::max(max_out,face.mNumIndices);
|
|
}
|
|
}
|
|
|
|
// Just another check whether aiMesh::mPrimitiveTypes is correct
|
|
ai_assert(numOut != pMesh->mNumFaces);
|
|
|
|
aiVector3D* nor_out = NULL;
|
|
|
|
// if we don't have normals yet, but expect them to be a cheap side
|
|
// product of triangulation anyway, allocate storage for them.
|
|
if (!pMesh->mNormals && get_normals) {
|
|
// XXX need a mechanism to inform the GenVertexNormals process to treat these normals as preprocessed per-face normals
|
|
// nor_out = pMesh->mNormals = new aiVector3D[pMesh->mNumVertices];
|
|
}
|
|
|
|
// the output mesh will contain triangles, but no polys anymore
|
|
pMesh->mPrimitiveTypes |= aiPrimitiveType_TRIANGLE;
|
|
pMesh->mPrimitiveTypes &= ~aiPrimitiveType_POLYGON;
|
|
|
|
aiFace* out = new aiFace[numOut](), *curOut = out;
|
|
std::vector<aiVector3D> temp_verts3d(max_out+2); /* temporary storage for vertices */
|
|
std::vector<aiVector2D> temp_verts(max_out+2);
|
|
|
|
// Apply vertex colors to represent the face winding?
|
|
#ifdef AI_BUILD_TRIANGULATE_COLOR_FACE_WINDING
|
|
if (!pMesh->mColors[0])
|
|
pMesh->mColors[0] = new aiColor4D[pMesh->mNumVertices];
|
|
else
|
|
new(pMesh->mColors[0]) aiColor4D[pMesh->mNumVertices];
|
|
|
|
aiColor4D* clr = pMesh->mColors[0];
|
|
#endif
|
|
|
|
#ifdef AI_BUILD_TRIANGULATE_DEBUG_POLYS
|
|
FILE* fout = fopen(POLY_OUTPUT_FILE,"a");
|
|
#endif
|
|
|
|
const aiVector3D* verts = pMesh->mVertices;
|
|
|
|
// use std::unique_ptr to avoid slow std::vector<bool> specialiations
|
|
std::unique_ptr<bool[]> done(new bool[max_out]);
|
|
for( unsigned int a = 0; a < pMesh->mNumFaces; a++) {
|
|
aiFace& face = pMesh->mFaces[a];
|
|
|
|
unsigned int* idx = face.mIndices;
|
|
int num = (int)face.mNumIndices, ear, tmp, prev = num - 1, next = 0, max = num;
|
|
|
|
// Apply vertex colors to represent the face winding?
|
|
#ifdef AI_BUILD_TRIANGULATE_COLOR_FACE_WINDING
|
|
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;
|
|
|
|
// 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 = NULL;
|
|
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 = NULL;
|
|
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.
|
|
|
|
// RERQUIREMENT: 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 (tmp = 0; tmp < max; ++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,max,&temp_verts3d.front().x,&temp_verts3d.front().y,&temp_verts3d.front().z);
|
|
if (nor_out) {
|
|
for (tmp = 0; tmp < max; ++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);
|
|
}
|
|
|
|
for (tmp =0; tmp < max; ++tmp) {
|
|
temp_verts[tmp].x = verts[idx[tmp]][ac];
|
|
temp_verts[tmp].y = verts[idx[tmp]][bc];
|
|
done[tmp] = false;
|
|
}
|
|
|
|
#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
|
|
|
|
//
|
|
// FIXME: currently this is the slow O(kn) variant with a worst case
|
|
// complexity of O(n^2) (I think). Can be done in O(n).
|
|
while (num > 3) {
|
|
|
|
// Find the next ear of the polygon
|
|
int num_found = 0;
|
|
for (ear = next;;prev = ear,ear = next) {
|
|
|
|
// break after we looped two times without a positive match
|
|
for (next=ear+1;done[(next>=max?next=0:next)];++next);
|
|
if (next < ear) {
|
|
if (++num_found == 2) {
|
|
break;
|
|
}
|
|
}
|
|
const aiVector2D* pnt1 = &temp_verts[ear],
|
|
*pnt0 = &temp_verts[prev],
|
|
*pnt2 = &temp_verts[next];
|
|
|
|
// Must be a convex point. Assuming ccw winding, it must be on the right of the line between p-1 and p+1.
|
|
if (OnLeftSideOfLine2D(*pnt0,*pnt2,*pnt1)) {
|
|
continue;
|
|
}
|
|
|
|
// and no other point may be contained in this triangle
|
|
for ( tmp = 0; tmp < max; ++tmp) {
|
|
|
|
// We need to compare the actual values because it's possible that multiple indexes in
|
|
// the polygon are referring to the same position. concave_polygon.obj is a sample
|
|
//
|
|
// FIXME: Use 'epsiloned' comparisons instead? Due to numeric inaccuracies in
|
|
// PointInTriangle() I'm guessing that it's actually possible to construct
|
|
// input data that would cause us to end up with no ears. The problem is,
|
|
// which epsilon? If we chose a too large value, we'd get wrong results
|
|
const aiVector2D& vtmp = temp_verts[tmp];
|
|
if ( vtmp != *pnt1 && vtmp != *pnt2 && vtmp != *pnt0 && PointInTriangle2D(*pnt0,*pnt1,*pnt2,vtmp)) {
|
|
break;
|
|
}
|
|
}
|
|
if (tmp != max) {
|
|
continue;
|
|
}
|
|
|
|
// this vertex is an ear
|
|
break;
|
|
}
|
|
if (num_found == 2) {
|
|
|
|
// Due to the 'two ear theorem', every simple polygon with more than three points must
|
|
// have 2 'ears'. Here's definitely something wrong ... but we don't give up yet.
|
|
//
|
|
|
|
// Instead we're continuing with the standard tri-fanning algorithm which we'd
|
|
// use if we had only convex polygons. That's life.
|
|
ASSIMP_LOG_ERROR("Failed to triangulate polygon (no ear found). Probably not a simple polygon?");
|
|
|
|
#ifdef AI_BUILD_TRIANGULATE_DEBUG_POLYS
|
|
fprintf(fout,"critical error here, no ear found! ");
|
|
#endif
|
|
num = 0;
|
|
break;
|
|
|
|
curOut -= (max-num); /* undo all previous work */
|
|
for (tmp = 0; tmp < max-2; ++tmp) {
|
|
aiFace& nface = *curOut++;
|
|
|
|
nface.mNumIndices = 3;
|
|
if (!nface.mIndices)
|
|
nface.mIndices = new unsigned int[3];
|
|
|
|
nface.mIndices[0] = 0;
|
|
nface.mIndices[1] = tmp+1;
|
|
nface.mIndices[2] = tmp+2;
|
|
|
|
}
|
|
num = 0;
|
|
break;
|
|
}
|
|
|
|
aiFace& nface = *curOut++;
|
|
nface.mNumIndices = 3;
|
|
|
|
if (!nface.mIndices) {
|
|
nface.mIndices = new unsigned int[3];
|
|
}
|
|
|
|
// setup indices for the new triangle ...
|
|
nface.mIndices[0] = prev;
|
|
nface.mIndices[1] = ear;
|
|
nface.mIndices[2] = next;
|
|
|
|
// exclude the ear from most further processing
|
|
done[ear] = true;
|
|
--num;
|
|
}
|
|
if (num > 0) {
|
|
// We have three indices forming the last 'ear' remaining. Collect them.
|
|
aiFace& nface = *curOut++;
|
|
nface.mNumIndices = 3;
|
|
if (!nface.mIndices) {
|
|
nface.mIndices = new unsigned int[3];
|
|
}
|
|
|
|
for (tmp = 0; done[tmp]; ++tmp);
|
|
nface.mIndices[0] = tmp;
|
|
|
|
for (++tmp; done[tmp]; ++tmp);
|
|
nface.mIndices[1] = tmp;
|
|
|
|
for (++tmp; done[tmp]; ++tmp);
|
|
nface.mIndices[2] = tmp;
|
|
|
|
}
|
|
}
|
|
|
|
#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;
|
|
|
|
// drop dumb 0-area triangles - deactivated for now:
|
|
//FindDegenerates post processing step can do the same thing
|
|
//if (std::fabs(GetArea2D(temp_verts[i[0]],temp_verts[i[1]],temp_verts[i[2]])) < 1e-5f) {
|
|
// ASSIMP_LOG_DEBUG("Dropping triangle with area 0");
|
|
// --curOut;
|
|
|
|
// delete[] f->mIndices;
|
|
// f->mIndices = nullptr;
|
|
|
|
// for(aiFace* ff = f; ff != curOut; ++ff) {
|
|
// ff->mNumIndices = (ff+1)->mNumIndices;
|
|
// ff->mIndices = (ff+1)->mIndices;
|
|
// (ff+1)->mIndices = nullptr;
|
|
// }
|
|
// continue;
|
|
//}
|
|
|
|
i[0] = idx[i[0]];
|
|
i[1] = idx[i[1]];
|
|
i[2] = idx[i[2]];
|
|
++f;
|
|
}
|
|
|
|
delete[] face.mIndices;
|
|
face.mIndices = NULL;
|
|
}
|
|
|
|
#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
|