         float c = sqrt((a * a) + (b * b));
 
         float c_angle = asin(a/c);       // computed angle (rad) of pixel in unit circle
-        c_angle = c_angle * 180.0 / pi;  // convert to degrees
+        c_angle = c_angle * to_degrees;  // convert to degrees
 
         if (uv.x < 0.5 && uv.y > 0.5)    // 2nd quadrant
             c_angle = 180.0 - c_angle;


        // Frag contained in angle
        //if (c_angle <= u_angle) {
        if (c_angle <= u_angle) {
            gl_FragColor = vec4(filling_green, 1.0);
        }


vec3 full_green = vec3(0.2, 0.8, 0.2);
vec3 filling_green = vec3(0.5, 0.8, 0.2);
float pi = 3.1415926;
float to_degrees = 57.2958; // 180 / pi

void main() {
    vec2 uv = vTextureCoord / vec2(u_radius / u_screenSize.x, u_radius / u_screenSize.y);
