SgMesh* MeshGenerator::generateExtrusion(const Extrusion& extrusion)
{
const int numSpines = extrusion.spine.size();
const int numCrosses = extrusion.crossSection.size();
bool isClosed = false;
if(extrusion.spine[0][0] == extrusion.spine[numSpines - 1][0] &&
extrusion.spine[0][1] == extrusion.spine[numSpines - 1][1] &&
extrusion.spine[0][2] == extrusion.spine[numSpines - 1][2] ){
isClosed = true;
}
bool isCrossSectionClosed = (extrusion.crossSection[0] == extrusion.crossSection[numCrosses - 1]);
SgMesh* mesh = new SgMesh;
SgVertexArray& vertices = *mesh->setVertices(new SgVertexArray());
vertices.reserve(numSpines * numCrosses);
Vector3 preZaxis(Vector3::Zero());
int definedZaxis = -1;
vector<Vector3> Yaxisarray;
vector<Vector3> Zaxisarray;
if(numSpines > 2){
for(int i=0; i < numSpines; ++i){
Vector3 Yaxis, Zaxis;
if(i == 0){
if(isClosed){
const Vector3& spine1 = extrusion.spine[numSpines - 2];
const Vector3& spine2 = extrusion.spine[0];
const Vector3& spine3 = extrusion.spine[1];
Yaxis = spine3 - spine1;
Zaxis = (spine3 - spine2).cross(spine1 - spine2);
} else {
const Vector3& spine1 = extrusion.spine[0];
const Vector3& spine2 = extrusion.spine[1];
const Vector3& spine3 = extrusion.spine[2];
Yaxis = spine2 - spine1;
Zaxis = (spine3 - spine2).cross(spine1 - spine2);
}
} else if(i == numSpines - 1){
if(isClosed){
const Vector3& spine1 = extrusion.spine[numSpines - 2];
const Vector3& spine2 = extrusion.spine[0];
const Vector3& spine3 = extrusion.spine[1];
Yaxis = spine3 - spine1;
Zaxis = (spine3 - spine2).cross(spine1 - spine2);
} else {
const Vector3& spine1 = extrusion.spine[numSpines - 3];
const Vector3& spine2 = extrusion.spine[numSpines - 2];
const Vector3& spine3 = extrusion.spine[numSpines - 1];
Yaxis = spine3 - spine2;
Zaxis = (spine3 - spine2).cross(spine1 - spine2);
}
} else {
const Vector3& spine1 = extrusion.spine[i - 1];
const Vector3& spine2 = extrusion.spine[i];
const Vector3& spine3 = extrusion.spine[i + 1];
Yaxis = spine3 - spine1;
Zaxis = (spine3-spine2).cross(spine1-spine2);
}
if(!Zaxis.norm()){
if(definedZaxis != -1)
Zaxis = preZaxis;
} else {
if(definedZaxis == -1){
definedZaxis = i;
}
preZaxis = Zaxis;
}
Yaxisarray.push_back(Yaxis);
Zaxisarray.push_back(Zaxis);
}
} else {
const Vector3 Yaxis(extrusion.spine[1] - extrusion.spine[0]);
Yaxisarray.push_back(Yaxis);
Yaxisarray.push_back(Yaxis);
}
const int numScales = extrusion.scale.size();
const int numOrientations = extrusion.orientation.size();
Vector3 scale(1.0, 0.0, 1.0);
AngleAxis orientation(0.0, Vector3::UnitZ());
for(int i=0; i < numSpines; ++i){
Matrix3 Scp;
Vector3 y = Yaxisarray[i].normalized();
if(definedZaxis == -1){
AngleAxis R(acos(y[1]), Vector3(y[2], 0.0, -y[0]));
Scp = R.toRotationMatrix();
} else {
if(i < definedZaxis){
Zaxisarray[i] = Zaxisarray[definedZaxis];
}
if(i && (Zaxisarray[i].dot(Zaxisarray[i - 1]) < 0.0)){
Zaxisarray[i] *= -1.0;
}
Vector3 z = Zaxisarray[i].normalized();
Vector3 x = y.cross(z);
Scp << x, y, z;
}
const Vector3& spine = extrusion.spine[i];
if(numScales == 1){
scale << extrusion.scale[0][0], 0.0, extrusion.scale[0][1];
} else if(numScales > 1){
scale << extrusion.scale[i][0], 0.0, extrusion.scale[i][1];
}
if(numOrientations == 1){
orientation = extrusion.orientation[0];
} else if(numOrientations > 1){
orientation = extrusion.orientation[i];
}
for(int j=0; j < numCrosses; ++j){
const Vector3 crossSection(extrusion.crossSection[j][0], 0.0, extrusion.crossSection[j][1]);
const Vector3 v1(crossSection[0] * scale[0], 0.0, crossSection[2] * scale[2]);
const Vector3 v = Scp * orientation.toRotationMatrix() * v1 + spine;
vertices.push_back(v.cast<float>());
}
}
for(int i=0; i < numSpines - 1 ; ++i){
const int upper = i * numCrosses;
const int lower = (i + 1) * numCrosses;
for(int j=0; j < numCrosses - 1; ++j) {
mesh->addTriangle(j + upper, j + lower, (j + 1) + lower);
mesh->addTriangle(j + upper, (j + 1) + lower, j + 1 + upper);
}
}
int j = 0;
if(isCrossSectionClosed){
j = 1;
}
Triangulator<SgVertexArray> triangulator;
vector<int> polygon;
if(extrusion.beginCap && !isClosed){
triangulator.setVertices(vertices);
polygon.clear();
for(int i=0; i < numCrosses - j; ++i){
polygon.push_back(i);
}
triangulator.apply(polygon);
const vector<int>& triangles = triangulator.triangles();
for(size_t i=0; i < triangles.size(); i += 3){
mesh->addTriangle(polygon[triangles[i]], polygon[triangles[i+1]], polygon[triangles[i+2]]);
}
}
if(extrusion.endCap && !isClosed){
triangulator.setVertices(vertices);
polygon.clear();
for(int i=0; i < numCrosses - j; ++i){
polygon.push_back(numCrosses * (numSpines - 1) + i);
}
triangulator.apply(polygon);
const vector<int>& triangles = triangulator.triangles();
for(size_t i=0; i < triangles.size(); i +=3){
mesh->addTriangle(polygon[triangles[i]], polygon[triangles[i+2]], polygon[triangles[i+1]]);
}
}
mesh->updateBoundingBox();
generateNormals(mesh, extrusion.creaseAngle);
return mesh;
}
