// p is a point
const auto pv = p.getVector3fMap();
const uint32_t rgb = *reinterpret_cast<const int*>(&p.rgb);
int r = int((rgb >> 16) & 0x0000ff);
int g = int((rgb >> 8)  & 0x0000ff);
int b = int((rgb)       & 0x0000ff);