RRSolver is a global illumination solver. For offline rendering, it is complete and it can be used immediately. For realtime rendering, subclass RRSolver and implement tasks specific for your renderer.

OpenGL

rr_gl::RRSolverGL, subclass of RRSolver already implements GPU tasks using OpenGL. If you plan to use OpenGL realtime renderer (Lightsprint or any other), use it, no subclassing is necessary.

Direct3D/other

If you need global illumination in Direct3D/other renderer, subclass RRSolver. The only additional function you need to implement is Detect direct illumination.