macOS

-> Note: For executables see Pyaket's FAQ

Q: Artifacts, black screens¶

Apple seems to be a bit iffy on supporting OpenGL at all, so a couple of common mistakes developers make aren't catched and automagically fixed by the driver.

Unreachable code¶

For example, the following code shows a white screen and keeps executing past the return statement into unreachable code, though using discard works normally:

void main() {
    if (true) {
        fragColor = vec4(0.5);
        return;
    }
    fragColor = vec4(1.0);
}

Uninitialized memory¶

Artifacts are often caused by bad memory initialization; the code below should run without issues on any amd, intel, nvidia system in windows or linux, but fail in macOS:

void main() {
    fragColor.rgb += vec3(1, 0, 0);
    fragColor.a = 1.0;
}

Reason being the fragColor variable isn't initialized to vec4(0), a fix is to do it explicitly:

void main() {
    fragColor = vec4(0);
    fragColor.rgb += vec3(1, 0, 0);
    fragColor.a = 1.0;
}

Texture indices¶

Apparently, no texture() method works if the bindings aren't contiguous - that is, (0, 1, 2, 3...)

The ShaderTexture and ShaderProgram modules already handles this internally, but whether you're extending or using other ModernGL features, it's worth a check for the case.