Function newstyle_StartInstanceMatrix

physics/newstyle_fi.cpp:230–272

instance at specified point with specified orientation if matrix==NULL, don't modify matrix. This will be like doing an offset

// instance at specified point with specified orientation
// if matrix==NULL, don't modify matrix.  This will be like doing an offset
void newstyle_StartInstanceMatrix(vector *pos, matrix *orient) {
  vector tempv, temp0, temp1;
  matrix tempm, tempm2;

  ASSERT(instance_depth < MAX_INSTANCE_DEPTH);

  instance_stack[instance_depth].m = View_matrix;
  instance_stack[instance_depth].p = View_position;
  instance_stack[instance_depth].p0 = *fvi_query_ptr->p0;
  instance_stack[instance_depth].p1 = *fvi_query_ptr->p1;
  if (fvi_do_orient) {
    instance_stack[instance_depth].fvec = fvi_move_fvec;
    instance_stack[instance_depth].uvec = fvi_move_uvec;
  }
  instance_depth++;

  // step 1: subtract object position from view position

  tempv = View_position - *pos;
  temp0 = *fvi_query_ptr->p0 - *pos;
  temp1 = *fvi_query_ptr->p1 - *pos;

  if (orient) {
    // step 2: rotate view vector through object matrix

    View_position = tempv * *orient;
    *fvi_query_ptr->p0 = temp0 * *orient;
    *fvi_query_ptr->p1 = temp1 * *orient;

    if (fvi_do_orient) {
      fvi_move_fvec = fvi_move_fvec * *orient;
      fvi_move_uvec = fvi_move_uvec * *orient;
    }

    // step 3: rotate object matrix through view_matrix (vm = ob * vm)

    tempm2 = ~*orient;

    tempm = tempm2 * View_matrix;

    View_matrix = tempm;
  }
}

// instance at specified point with specified orientation
// if angles==NULL, don't modify matrix.  This will be like doing an offset