Function BuildElementListForRoomFace

editor/editor_lighting.cpp:1393–1492

Important - vertnum is the index into the face_verts[] array in the face structure, not an index into the verts[] array of the room structure

// Important - vertnum is the index into the face_verts[] array in the face structure,
// not an index into the verts[] array of the room structure
void BuildElementListForRoomFace(int roomnum, int facenum, rad_surface *surf) {
  matrix face_matrix, trans_matrix;
  vector fvec;
  vector avg_vert;
  vector verts[MAX_VERTS_PER_FACE * 5];
  vector rot_vert;
  vector vert;
  int i, t;
  int xres, yres;
  int lmi_handle;
  int x1 = surf->x1;
  int y1 = surf->y1;

  xres = surf->xresolution;
  yres = surf->yresolution;

  ASSERT(Rooms[roomnum].used);
  ASSERT(Rooms[roomnum].faces[facenum].num_verts >= 3);
  ASSERT(Rooms[roomnum].faces[facenum].lmi_handle != BAD_LMI_INDEX);

  lmi_handle = Rooms[roomnum].faces[facenum].lmi_handle;
  avg_vert = ScratchCenters[lmi_handle];

  // Make the orientation matrix
  // Reverse the normal because we're looking "at" the face, not from it
  fvec = -LightmapInfo[lmi_handle].normal;

  vm_VectorToMatrix(&face_matrix, &fvec, NULL, NULL);
  // Make the transformation matrix

  angvec avec;
  vm_ExtractAnglesFromMatrix(&avec, &face_matrix);
  vm_AnglesToMatrix(&trans_matrix, avec.p, avec.h, avec.b);

  // Rotate all the points
  for (i = 0; i < Rooms[roomnum].faces[facenum].num_verts; i++) {
    vert = Rooms[roomnum].verts[Rooms[roomnum].faces[facenum].face_verts[i]];

    vert -= avg_vert;
    vm_MatrixMulVector(&rot_vert, &vert, &trans_matrix);

    verts[i] = rot_vert;
  }

  // Find a base vector
  vector base_vector;
  vector xdiff, ydiff;

  vm_MakeZero(&xdiff);
  vm_MakeZero(&ydiff);

  // Rotate our upper left point into our 2d space
  vert = LightmapInfo[lmi_handle].upper_left - avg_vert;
  vm_MatrixMulVector(&base_vector, &vert, &trans_matrix);

  xdiff.x = LightmapInfo[lmi_handle].xspacing;
  ydiff.y = LightmapInfo[lmi_handle].yspacing;