Function ClipPlane

renderer/HardwareClipper.cpp:287–332

}

int ClipPlane(int plane_flag, g3Point **src, g3Point **dest, int *nv, g3Codes *cc) {
  int i, prev, next;
  g3Point **save_dest = dest;

  // Init codes
  cc->cc_and = 0xff;
  cc->cc_or = 0;

  for (i = 0, prev = *nv - 1, next = 1; i < *nv; i++) {
    if (src[i]->p3_codes & plane_flag) {
      // cur point off?
      if (!(src[prev]->p3_codes & plane_flag)) {
        // prev not off?
        *dest = ClipEdge(plane_flag, src[prev], src[i]);
        cc->cc_or |= (*dest)->p3_codes;
        cc->cc_and &= (*dest)->p3_codes;
        dest++;
      }

      if (!(src[next]->p3_codes & plane_flag)) {
        *dest = ClipEdge(plane_flag, src[next], src[i]);
        cc->cc_or |= (*dest)->p3_codes;
        cc->cc_and &= (*dest)->p3_codes;
        dest++;
      }

      // see if must free discarded point
      if (src[i]->p3_flags & PF_TEMP_POINT) {
        FreeTempPoint(src[i]);
      }
    } else {
      // cur not off, copy to dest buffer
      *dest++ = src[i];

      cc->cc_or |= src[i]->p3_codes;
      cc->cc_and &= src[i]->p3_codes;
    }

    prev = i;
    if (++next == *nv) {
      next = 0;
    }
  }

  return (dest - save_dest);
}

// temp buffers for clipping
static g3Point *Vbuf0[MAX_POINTS_IN_POLY];