out vec4 sk_FragColor; uniform vec4 colorGreen; uniform vec4 colorRed; uniform mat2 testMatrix2x2; vec4 main() { vec4 f4 = vec4(testMatrix2x2); bool ok = mat2(f4.xyz, 4.0) == mat2(1.0, 2.0, 3.0, 4.0); ok = ok && mat3(f4.xy, f4.zw, f4, f4.x) == mat3(1.0, 2.0, 3.0, 4.0, 1.0, 2.0, 3.0, 4.0, 1.0); ok = ok && mat4(f4.xyz, f4.wxy, f4.zwxy, f4.zw, f4) == mat4(1.0, 2.0, 3.0, 4.0, 1.0, 2.0, 3.0, 4.0, 1.0, 2.0, 3.0, 4.0, 1.0, 2.0, 3.0, 4.0); return ok ? colorGreen : colorRed; }