Fix an unintended type conversion in the terrain shader #371
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This error was concealed by a recent change to wgpu, where it would automatically convert unsigned integers to floats when it deems it "safe" to do so. Previously, it would've given a validation error here because the hardcoded numbers aren't compiled to floats unless explicitly marked as such. Apparently, this hidden conversion broke the discard logic, leading to black surfaces being discarded in at least one case (c_tower1). This is because the division doesn't have enough precision if using integers. Being explicit fixes the problem.
Setting the alpha to zero has the same net effect, but it wastes GPU compute time as the rest of the shader program might still be executed - for no good reason, given that the fragment won't be visible anyway.
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This error was concealed by a recent change to wgpu, where it would automatically convert unsigned integers to floats when it deems it "safe" to do so. Previously, it would've given a validation error here because the hardcoded numbers aren't compiled to floats unless explicitly marked as such.
Apparently, this hidden conversion broke the discard logic, leading to black surfaces being discarded in at least one case (c_tower1). This is because the division doesn't have enough precision if using integers. Being explicit fixes the problem.
Edit: I also noticed the shader isn't actually discarding the fragment, which seems like a silly oversight.