bool Polyhedron::Intersects(const LineSegment &lineSegment) const
{
if (Contains(lineSegment))
return true;
for(int i = 0; i < NumFaces(); ++i)
{
float t;
Plane plane = FacePlane(i);
bool intersects = Plane::IntersectLinePlane(plane.normal, plane.d, lineSegment.a, lineSegment.b - lineSegment.a, t);
if (intersects && t >= 0.f && t <= 1.f)
if (FaceContains(i, lineSegment.GetPoint(t)))
return true;
}
return false;
}
void CalculateBoundaryVertexNormal3D(vector3& nOut, Grid& grid, Vertex* vrt,
TAAPosVRT& aaPos)
{
// The algorithm is a little cumbersome. However, through this setup, we
// make sure that the orientation of the normal indeed points outwards,
// based only on the topology.
// set nOut to 0
VecSet(nOut, 0);
// iterate over associated volumes
std::vector<Volume*> vols;
CollectAssociated(vols, grid, vrt);
FaceDescriptor fd;
for(size_t i_vol = 0; i_vol < vols.size(); ++i_vol){
Volume* v = vols[i_vol];
// check for each side of f whether it is a boundary edge
for(size_t i_side = 0; i_side < v->num_sides(); ++i_side){
if(IsBoundaryFace3D(grid, grid.get_face(v, i_side))){
v->face_desc(i_side, fd);
// make sure that fd contains the given vertex
if(!FaceContains(&fd, vrt))
continue;
// the normal pointing outwards is clearly defined from the
// orientation of the face descriptor
vector3 n;
CalculateNormal(n, &fd, aaPos);
VecAdd(nOut, nOut, n);
}
}
}
VecNormalize(nOut, nOut);
}
bool Polyhedron::Contains(const float3 &point) const
{
int numIntersections = 0;
for(int i = 0; i < (int)f.size(); ++i)
{
Plane p(v[f[i].v[0]] - point, v[f[i].v[1]] - point, v[f[i].v[2]] - point);
// Find the intersection of the plane and the ray (0,0,0) -> (t,0,0), t >= 0.
// <normal, point_on_ray> == d
// n.x * t == d
// t == d / n.x
if (Abs(p.normal.x) > 1e-5f)
{
float t = p.d / p.normal.x;
// If t >= 0, the plane and the ray intersect, and the ray potentially also intersects the polygon.
// Finish the test by checking whether the point of intersection is contained in the polygon, in
// which case the ray-polygon intersection occurs.
if (t >= 0.f && FaceContains(i, point + float3(t,0,0)))
++numIntersections;
}
}
return numIntersections % 2 == 1;
}
