1 #version 120

2

3 void main()

4 {

5 vec2 pt = gl_PointCoord.xy * 2.0 - 1.0;

6 float len = length(pt);

7 vec2 dir = pt / len;

8 float angle = atan(dir.y, dir.x);

9

10 float alpha = 1.0 - smoothstep(0.8, 0.9, len + abs(sin(angle * 8.0)) * 0.1);

11 gl_FragColor = vec4(1.0, 1.0, 1.0, alpha);

12 }