Function check_sphere_to_face

physics/findintersection.cpp:1596–1679

check if a sphere intersects a face

// check if a sphere intersects a face
int check_sphere_to_face(vector *colp, vector *intp, float *col_dist, vector *wall_norm, const vector *p0,
                         const vector *p1, vector *face_normal, int nv, float rad, vector **vertex_ptr_list) {
  uint32_t edgemask;

  ASSERT(nv > 0 && nv <= 32); // otherwise, we overflow the edgemask -- if we hit this we need to make edgemask a long
                              // long and adjust the other functions accordingly

  // now do 2d check to see if point is inside the face (if so, we are done)
  edgemask = check_point_to_face(colp, face_normal, nv, vertex_ptr_list);

  // If we are inside edgemask is 0, we hit the face.
  if (edgemask == 0) {
    //		mprintf(0, "CSTF Hit Face\n");
    *col_dist = vm_VectorDistance(p0, intp);
    *wall_norm = *face_normal;
    return IT_FACE;
  } else {
    // Although the plane collision point is not in the face, we might hit an edge.
    // If the checkpoint collides with the edge of a face, it could
    // go a little farther before hitting anything

    vector *v0, *v1;
    int edgenum;

    // If we have no radius we could only hit the face and not an edge or point
    if (rad == 0.0)
      return IT_NONE;

    int f_hit = 0;
    vector c_end = *p1;

    // get verts for edge we're behind
    for (edgenum = 0; edgenum < nv; edgenum++) {
      if (edgemask & 1) {
        v0 = vertex_ptr_list[edgenum];
        v1 = vertex_ptr_list[(edgenum + 1) % nv];

        if (check_vector_to_cylinder(colp, intp, col_dist, wall_norm, p0, &c_end, rad, v0, v1)) {
          c_end = *intp;
          f_hit = 1;
        }
      }

      edgemask = edgemask >> 1;
    }

    return f_hit;
  } /*	checkvec = *p0 - *v0;
           edgevec = *v1 - *v0;
           edgelen = vm_NormalizeVector(&edgevec);

           cur_dist = edgevec * checkvec;

           closest_point = *v0 + cur_dist * edgevec;

           // See if the sphere intersects the edge of the face
           if(!check_vector_to_sphere_1(intp, col_dist, p0, p1, &closest_point, rad, 1)) return IT_NONE;
           checkvec = *intp - *v0;