Thanks a lot kaud..

Im seeing somewhere else in legacy code, (for getting int value)

int iVal = 0;
OnePixel<int> iraster(&iVal);

RenderFuncParams rfp;
rfp.displayDataType = eDDT;
rfp.pInstance = pInstance;
rfp.pfOut = nullptr;
rfp.piOut = &iraster;

where piOut is just single value, not an array