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openscad
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master
Marius Kintel 2015-01-15 15:05:04 -05:00
parent 9087369863
commit 0e23303cbc
1 changed files with 39 additions and 10 deletions
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49
src/GeometryUtils.cc
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@ -15,6 +15,22 @@ static void stdFree(void* userData, void* ptr) {
free(ptr);
}
/*!
Tessellates input contours into a triangle mesh.
The input contours may consist of positive (CCW) and negative (CW)
contours. These define holes, and possibly islands.
The output will be written as indices into the input vertex vector.
This function should be robust wrt. malformed input.
It will only use existing vertices and is guaranteed use all
existing vertices, i.e. it will maintain connectivity if the input
polygon is part of a polygon mesh.
Returns true on error, false on success.
*/
bool GeometryUtils::tessellatePolygonWithHoles(const IndexedPolygons &polygons,
std::vector<IndexedTriangle> &triangles,
const Vector3f *normal)
@ -31,24 +47,21 @@ bool GeometryUtils::tessellatePolygonWithHoles(const IndexedPolygons &polygons,
TESSreal *normalvec = NULL;
TESSreal passednormal[3];
if (normal) {
passednormal[0] = normal->x();
passednormal[1] = normal->y();
passednormal[2] = normal->z();
passednormal[0] = (*normal)[0];
passednormal[1] = (*normal)[1];
passednormal[2] = (*normal)[2];
normalvec = passednormal;
}
int allocated = 0;
TESSalloc ma;
TESStesselator* tess = 0;
memset(&ma, 0, sizeof(ma));
ma.memalloc = stdAlloc;
ma.memfree = stdFree;
ma.userData = (void*)&allocated;
ma.extraVertices = 256; // realloc not provided, allow 256 extra vertices.
tess = tessNewTess(&ma);
if (!tess) return -1;
if (!(tess = tessNewTess(&ma))) return true;
int numContours = 0;
std::vector<TESSreal> contour;
@ -73,7 +86,23 @@ bool GeometryUtils::tessellatePolygonWithHoles(const IndexedPolygons &polygons,
const TESSindex *elements = tessGetElements(tess);
int numelems = tessGetElementCount(tess);
/*
At this point, we have a delaunay triangle mesh.
However, as libtess2 might merge vertices, as well as insert new
vertices for intersecting edges, we need to detect these and
insert dummy triangles to maintain external connectivity.
FIXME: This currently only works for polygons without holes.
*/
if (polygons.faces.size() == 1) { // Only works for polygons without holes
/*
Algorithm:
A) Collect all triangles using _only_ existing vertices -> triangles
B) Locate all unused vertices
C) For each unused vertex, create a triangle connecting it to the existing mesh
*/
int numInputVerts = polygons.faces[0].size();
std::vector<int> vflags(numInputVerts); // Init 0
@ -83,7 +112,7 @@ bool GeometryUtils::tessellatePolygonWithHoles(const IndexedPolygons &polygons,
for (int i=0;i<3;i++) {
int vidx = vindices[elements[t*3 + i]];
if (vidx == TESS_UNDEF) err = true;
else tri[i] = vidx;
else tri[i] = vidx; // A)
}
PRINTDB("%d (%d) %d (%d) %d (%d)",
elements[t*3 + 0] % vindices[elements[t*3 + 0]] %
@ -92,14 +121,14 @@ bool GeometryUtils::tessellatePolygonWithHoles(const IndexedPolygons &polygons,
// FIXME: We ignore self-intersecting triangles rather than detecting and handling this
if (!err) {
triangles.push_back(tri);
vflags[tri[0]] = 1;
vflags[tri[0]] = 1; // B)
vflags[tri[1]] = 1;
vflags[tri[2]] = 1;
}
}
for (int i=0;i<numInputVerts;i++) {
if (vflags[i] == 0) { // vertex missing in output
if (vflags[i] == 0) { // vertex missing in output: C)
int startv = (i+numInputVerts-1)%numInputVerts;
int j;
for (j = i; j < numInputVerts && vflags[j] == 0; j++) {