prosperon/source/shaders/circle.sglsl

@vs circle_vs
in vec2 vertex;
in vec2 apos;
in float aradius;
in vec4 acolor;
in float asegsize;
in float afill;

out vec2 coords;
out vec4 fcolor;
out float segsize;
out float fill;
out float radius;

uniform cvs_params { mat4 proj; };

void main()
{
  gl_Position = proj * vec4((vertex * aradius) + apos, 0.0, 1.0);
  coords = vertex;
  fcolor = acolor;
  segsize = asegsize;
  fill = afill;
  radius = aradius;
}
@end

@fs circle_fs

out vec4 color;

in vec2 coords;
in vec4 fcolor;
in float segsize;
in float fill;
in float radius;

#define PI 3.14

void main()
{
  float px = 1/radius;
  float R1 = 1.f;
  float R2 = 1.0 - fill;
  float dist = sqrt(pow(coords.x,2) + pow(coords.y,2));
  color = fcolor;

  float sm = 1 - smoothstep(R1-px,R1,dist);
  float sm2 = smoothstep(R2-px,R2,dist);
  float a = sm*sm2;
  color = mix(vec4(0,0,0,0), fcolor, a);

  if (segsize<0)
    return;

  float f = atan(coords.y, coords.x) + PI;

  if (mod(f, segsize) < segsize/2)
    discard;
}

@end

@program circle circle_vs circle_fs