  We have developed an event generator for direct-photon production in hadron
collisions, including associated two-jet production in the framework of the
GR@PPA event generator. The event generator consistently combines $\gamma$ +
2-jet production processes with the lowest-order $\gamma$ + jet and
photon-radiation (fragmentation) processes from QCD 2-jet production using a
subtraction method. The generated events can be fed to general-purpose event
generators to facilitate the addition of hadronization and decay simulations.
Using the obtained event information, we can simulate photon isolation and
hadron-jet reconstruction at the particle (hadron) level. The simulation
reasonably reproduces measurement data obtained at the LHC concerning not only
the inclusive photon spectrum, but also the correlation between the photon and
jet. The simulation implies that the contribution of the $\gamma$ + 2-jet is
very large, especially in low photon-$p_{T}$ ($\lesssim$ 50 GeV) regions.
Discrepancies observed at low $p_{T}$, although marginal, may indicate the
necessity for the consideration of further higher-order processes. Unambiguous
particle-level definition of the photon-isolation condition for the signal
events is desired to be given explicitly in future measurements.
