On quality levels 15 and up, Roblox AA takes over, overriding any graphics card AA. On D3D9 graphics, AA is not enabled. With D3D9 and quality level +15, Roblox AA overrides graphics card AA for no AA.
Repro: set graphics mode to D3D9, set graphics card AA, move the quality level above and below 15.
MSAA is not available on D3D9 at quality levels 14+, because it does not support MRT+MSAA.
I set my graphics card to use SSAA not MSAA. The problem is not that the AA provided by ROBLOX CORP is not available, the problem is that it’s hogging the AA and preventing the AA provided by Advanced Micro Devices inc. from working.
“AA provided by AMD Inc.” is incompatible with our render code under D3D9. Driver hacks in general only work for simple cases, and consistently fail when a game uses e.g. deferred shading, post-processing, even some advanced cases of forward rendering, whenever an intermediate render target is used.