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Better triangulation of quad into two triangles.

This commit is contained in:
Paolo Cignoni 2010-01-16 14:59:40 +00:00
parent c72bfe6f63
commit 14850843c6
1 changed files with 44 additions and 26 deletions
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46
wrap/io_trimesh/import_off.h
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@ -458,12 +458,10 @@ namespace vcg
{ {
for (int j = 0; j < 3; j++) for (int j = 0; j < 3; j++)
{ {
// Go to next line when needed if (k == tokens.size()) // if EOL // Go to next line when needed
if (k == tokens.size()) // if EOL
{ {
TokenizeNextLine(stream, tokens); TokenizeNextLine(stream, tokens);
if (tokens.size() == 0) // if EOF if (tokens.size() == 0) return InvalidFile; // if EOF
return InvalidFile;
k = 0; k = 0;
} }
@ -477,38 +475,58 @@ namespace vcg
unsigned int trigs = vert_per_face-3; // number of extra faces to add unsigned int trigs = vert_per_face-3; // number of extra faces to add
nFaces += trigs; nFaces += trigs;
Allocator<MESH_TYPE>::AddFaces(mesh, trigs); Allocator<MESH_TYPE>::AddFaces(mesh, trigs);
int *vertIndices = new int[vert_per_face]; std::vector<int> vertIndices(vert_per_face);
for (int j=0; j < vert_per_face; j++) for (int j=0; j < vert_per_face; j++)
{ {
// Go to next line when needed if (k == tokens.size()) // if EOL // Go to next line when needed
if (k == tokens.size()) // if EOL
{ {
TokenizeNextLine(stream, tokens); TokenizeNextLine(stream, tokens);
if (tokens.size() == 0) // if EOF if (tokens.size() == 0) return InvalidFile; // if EOF
return InvalidFile;
k = 0; k = 0;
} }
vertIndices[j] = atoi(tokens[k].c_str()); vertIndices[j] = atoi(tokens[k].c_str());
k++; k++;
} }
if(vert_per_face==4)
{ // To well triangulate the quad:
// if the quad is flat and convex we use the shortest diag ,
// else we should use the diag that makes the smallest
const CoordType &P0=mesh.vert[vertIndices[0]].cP();
const CoordType &P1=mesh.vert[vertIndices[1]].cP();
const CoordType &P2=mesh.vert[vertIndices[2]].cP();
const CoordType &P3=mesh.vert[vertIndices[3]].cP();
CoordType N00 = Normal(P0,P1,P2);
CoordType N01 = Normal(P0,P2,P3);
CoordType N10 = Normal(P1,P2,P3);
CoordType N11 = Normal(P1,P3,P0);
ScalarType Angle0Rad=Angle(N00,N01);
ScalarType Angle1Rad=Angle(N10,N11);
// QualityRadii is inradius/circumradius; bad when close to zero.
// swap diagonal if the worst triangle improve.
bool qualityImprove = std::min(QualityRadii(P0,P1,P2),QualityRadii(P0,P2,P3)) < std::min(QualityRadii(P1,P2,P3),QualityRadii(P1,P3,P0));
bool swapCauseFlip = (Angle1Rad > M_PI/2.0) && (Angle0Rad <M_PI/2.0);
if(qualityImprove && ! swapCauseFlip)
std::rotate(vertIndices.begin(), vertIndices.begin()+1, vertIndices.end());
}
// standard fan triangulation (we hope the polygon is convex...)
for (int j=0; j<=vert_per_face-3; j++) for (int j=0; j<=vert_per_face-3; j++)
{ {
mesh.face[f+j].V(0) = &(mesh.vert[ vertIndices[0 ] ]); mesh.face[f+j].V(0) = &(mesh.vert[ vertIndices[0 ] ]);
mesh.face[f+j].V(1) = &(mesh.vert[ vertIndices[1+j] ]); mesh.face[f+j].V(1) = &(mesh.vert[ vertIndices[1+j] ]);
mesh.face[f+j].V(2) = &(mesh.vert[ vertIndices[2+j] ]); mesh.face[f+j].V(2) = &(mesh.vert[ vertIndices[2+j] ]);
if (tri::HasPerFaceFlags(mesh)) { if (tri::HasPerFaceFlags(mesh)) {
// tag internal polygnal edges as "faux" // tag internal polygonal edges as "faux"
if (j>0) mesh.face[f+j].SetF(0); if (j>0) mesh.face[f+j].SetF(0);
if (j<vert_per_face-3) mesh.face[f+j].SetF(2); if (j<vert_per_face-3) mesh.face[f+j].SetF(2);
loadmask |= Mask::IOM_BITPOLYGONAL; loadmask |= Mask::IOM_BITPOLYGONAL;
} }
} }
f+=trigs; f+=trigs;
delete [] vertIndices;
} }
// NOTE: It is assumed that colored face takes exactly one text line // NOTE: It is assumed that colored face takes exactly one text line