A few more softgpu optimizations for alpha blend/test #16502
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Since we're already checking the CLUT, we can tell if it doesn't contain zero alpha, in which case a != 0 test will never fail. This is actually pretty common, even when texture alpha is not always FF.
Blending is slow, and often games do effects like smoke, sun, etc. that has a lot of zero alpha in them. Many games do this with alpha testing off, which is cheap compared to blending.
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This forces alpha test off in more scenarios (it's still common to have a texture that contains no alpha, but has otherwise variable alpha) and forces alpha testing on when it could help skip a lot of alpha blending.
With these recent optimizations, the title screen of the GOW demo has crept from ~91% to ~97% speed on my machine. This one helped another couple percent, and helped a Red Star framedump I had by around ~4% (thought that was from ~165% already.)
-[Unknown]