Hi, I try to understand what will GPU do with the different swap effects. I can't understand this in the document for D3DSWAPEFFECT_DISCARD : This is also the only swap effect that may be used when specifying a value other than D3DMULTISAMPLE_NONE for the MultiSampleType member of D3DPRESENT_PARAMETERS. Why multi sample only supports discard swap effect? For flip swap effect, can't it just render to the multi sampled back buffer then swap the pointer? For copy swap effect, can't it just cope the multi sampled pixel? Could someone help? Thanks.