Lets say you're rendering to a texture with 4x multisampling, which means you have 4 samples per pixel. That mask controls whether the GPU is allowed to write to each of those 4 samples. So for instance lets say you passed a value of 0x7. That integer has a value of 1 for bit 0, 1 for bit 1, 1 for bit 2. and 0 for bit 3. This means that the GPU would never write to the 4th sample in the texture, it only write to the first 3.
So if i don't use msaa(otherwise , mass count =1),and i use sample mask:0xfffffffe or 0x0, the render target will never be drawn by GPU?
this seems strange, if i use 4x MSAA, what reason make me use just sample first 3?