1#version 120 2 3varying vec4 var_color; 4 5#define PI 3.141592653589793 6 7void main() { 8 // Empirically found shading function that got consensus. 9 float alpha = pow(cos(var_color.a * PI / 2), 1.5); 10 gl_FragColor = vec4(var_color.r, var_color.g, var_color.b, alpha); 11} 12