virtual bool IsPrepassRequired() const;
Most platforms do not require the prepass step (except X360/Wii), their HALs override this function. Otherwise, if both passes are requested at once, (and prepass is not required), the prepass rendering is done inline with main display, instead of consecutively. On platforms that do not require prepasses, one can still be achieved by calling Display multiple times with individual pass arguments.
Returns true if prepass is required and false otherwise.