1
2out vec4 sk_FragColor;
3uniform float a;
4uniform float b;
5uniform vec4 c;
6uniform vec4 d;
7void main() {
8    sk_FragColor.x = atan(a);
9    sk_FragColor.x = atan(a, b);
10    sk_FragColor = atan(c);
11    sk_FragColor = atan(c, d);
12}
13