struct Uniforms { float a; float b; }; struct Inputs { }; struct Outputs { float4 sk_FragColor [[color(0)]]; }; fragment Outputs fragmentMain(Inputs _in [[stage_in]], constant Uniforms& _uniforms [[buffer(0)]], bool _frontFacing [[front_facing]], float4 _fragCoord [[position]]) { Outputs _out; (void)_out; _out.sk_FragColor.x = step(_uniforms.a, _uniforms.b); return _out; }