Point inside given shape

[Rennngw]

Hi,

I have a static closed STL shape in 3D (for example, a tetrahedron). I am sampling points randomly in 3D space. I need to consider points that are inside the shape.

Is it possible to implement using the FCL library?

[lmontaut]

Hi @Rennngw,
In the hppfcl3x branch, if your object is convex, you can load it by using a MeshLoader then call the buildConvexHull method of BVHs:

std::shared_ptr<ConvexBase> loadConvexShape(const std::string& file_name) {
  NODE_TYPE bv_type = BV_AABB;
  MeshLoader loader(bv_type);
  BVHModelPtr_t bvh = loader.load(file_name);
  bvh->buildConvexHull(true, "Qt");
  return bvh->convex;
}

// ...
// inside main function
std::shared_ptr<ConvexBase> shape = loadConvexShape("obj.stl");

You can then access the faces normals and faces offsets of the mesh to check if your points are inside/outside the shapes (by considering all hyperplanes defining your shape):

shape->normals[i];
shape->offsets[i];