Function BSPPointInPolygon

Descent3/bsp.cpp:1076–1124

Returns true if passed in point collides with a nodes polygon

// Returns true if passed in point collides with a nodes polygon
static inline int BSPPointInPolygon(vector *pos, bspnode *node) {
  if (node->node_subnum < 0) // Room face
  {
    room *rp = &Rooms[node->node_roomnum];
    face *fp = &rp->faces[node->node_facenum];
    if (!(BSPInMinMax(pos, &fp->min_xyz, &fp->max_xyz)))
      return 0;

    // Test to see if this point in inside the polygon
    vector verts[MAX_VERTS_PER_FACE], *vertp[MAX_VERTS_PER_FACE];
    for (int i = 0; i < fp->num_verts; i++) {
      verts[i] = rp->verts[fp->face_verts[i]];
      vertp[i] = &verts[i];
    }

    if ((check_point_to_face(pos, &fp->normal, fp->num_verts, vertp)))
      return 0;

    return 1;
  } else // Object face
  {
    object *obj = &Objects[node->node_roomnum];

    if (!(BSPInMinMax(pos, &obj->min_xyz, &obj->max_xyz)))
      return 0;

    // Test to see if this point in inside the polygon
    vector verts[MAX_VERTS_PER_FACE], *vertp[MAX_VERTS_PER_FACE];
    vector norm;
    poly_model *po = &Poly_models[obj->rtype.pobj_info.model_num];
    bsp_info *sm = &po->submodel[node->node_subnum];

    for (int i = 0; i < sm->faces[node->node_facenum].nverts; i++) {
      GetObjectPointInWorld(&verts[i], obj, node->node_subnum, sm->faces[node->node_facenum].vertnums[i]);
      vertp[i] = &verts[i];
    }

    norm.x = node->plane.a;
    norm.y = node->plane.b;
    norm.z = node->plane.c;

    if ((check_point_to_face(pos, &norm, sm->faces[node->node_facenum].nverts, vertp)))
      return 0;

    return 1;
  }

  return 0;
}

// Runs a ray through the bsp tree
// Returns true if a ray is occludes