// Create a polygonal mesh for this torus using parameterization as follows:
// u = [0, 2*Pi] traces a circle in the x-y plane with radius torusRadius,
// which is the centroid of the torus. A point P on this circle is
// given by P = torusRadius*~[cos(u) sin(u) 0].
// v = [0, 2*Pi] traces a circle arond the cross-section (or tube) of the
// torus with radius tubeRadius, at a given u. A point Q on this circle
// is given by Q = (torusRadius + tubeRadius*cos(v))*e1 + tubeRadius*(~[0 0 1]*sin(v))
// where e1 = ~[sin(u) cos(u) 0]. The tube circle is in a plane spanned
// by e1 and the z-axis.
void ContactGeometry::Torus::Impl::createPolygonalMesh(PolygonalMesh& mesh) const {
// TODO add resolution argument
const int numSides = 12; //*resolution;
const int numSlices = 36; //*resolution;
// add vertices
for (int i = 0; i < numSlices; ++i) {
Real u = Real((i*2*SimTK_PI)/numSlices);
UnitVec3 e1(std::sin(u), std::cos(u), 0); // torus circle aligned with z-axis (z-axis through hole)
for (int j = 0; j < numSides; ++j) {
Real v = Real((j*2*SimTK_PI)/numSides);
Vec3 vtx = (torusRadius + tubeRadius*std::cos(v))*e1 + tubeRadius*std::sin(v)*Vec3(0,0,1); // use ZAXIS?
mesh.addVertex(vtx);
}
}
// add faces, be careful to wrap indices for the last slice
int numVertices = mesh.getNumVertices();
// cout << "num verts = " << numVertices << endl;
for (int i = 0; i < numVertices; ++i) {
// cout << "v" << i << ": " << mesh.getVertexPosition(i) << endl;
// define counter-clockwise quad faces
Array_<int> faceIndices;
faceIndices.push_back(i); // u_i,v_i
faceIndices.push_back((i+1)%numVertices); // u_i, v_i+1
faceIndices.push_back((i+1+numSides)%numVertices); // u_i+1, v_i+1
faceIndices.push_back((i+numSides)%numVertices); // u_i+1, v_i
mesh.addFace(faceIndices);
}
}
void ContactGeometry::TriangleMesh::Impl::
createPolygonalMesh(PolygonalMesh& mesh) const {
for (unsigned vx=0; vx < vertices.size(); ++vx)
mesh.addVertex(vertices[vx].pos);
for (unsigned fx=0; fx < faces.size(); ++fx) {
const Face& face = faces[fx];
const ArrayViewConst_<int> verts(face.vertices, face.vertices+3);
mesh.addFace(verts);
}
}
void testCreateMesh() {
PolygonalMesh mesh;
ASSERT(mesh.getNumFaces() == 0);
ASSERT(mesh.getNumVertices() == 0);
ASSERT(mesh.addVertex(Vec3(0)) == 0);
ASSERT(mesh.addVertex(Vec3(0, 1, 0)) == 1);
ASSERT(mesh.addVertex(Vec3(0, 0, 1)) == 2);
Array_<int> v;
v.push_back(1);
v.push_back(2);
v.push_back(0);
ASSERT(mesh.addFace(v) == 0);
ASSERT(mesh.getNumFaces() == 1);
ASSERT(mesh.getNumVertices() == 3);
ASSERT(mesh.getFaceVertex(0, 0) == 1);
ASSERT(mesh.getFaceVertex(0, 1) == 2);
ASSERT(mesh.getFaceVertex(0, 2) == 0);
ASSERT(mesh.getVertexPosition(0) == Vec3(0));
ASSERT(mesh.getVertexPosition(1) == Vec3(0, 1, 0));
ASSERT(mesh.getVertexPosition(2) == Vec3(0, 0, 1));
// Make sure copy and assignment are shallow.
PolygonalMesh mesh2(mesh); // shallow copy construction
ASSERT(&mesh2.getImpl() == &mesh.getImpl());
ASSERT(mesh.getImplHandleCount()==2);
PolygonalMesh mesh3;
mesh3 = mesh; // shallow assignment
ASSERT(&mesh3.getImpl() == &mesh.getImpl());
ASSERT(mesh.getImplHandleCount()==3);
PolygonalMesh mesh4;
mesh4.copyAssign(mesh); // deep copy
ASSERT(mesh4.getNumVertices() == mesh.getNumVertices());
ASSERT(&mesh4.getImpl() != &mesh.getImpl());
ASSERT(mesh4.getImplHandleCount()==1);
ASSERT(mesh.getImplHandleCount()==3);
}