3dexperiments/assets/shaders/font.fs

precision mediump float;

varying vec2 uv;

uniform vec3 uColor;
uniform sampler2D texture0;

uniform float uWidth;
uniform float uEdge;

uniform float uOutlineWidth;
uniform float uOutlineEdge;

uniform vec2 uOutlineOffset;

uniform vec3 uOutlineColor;

void main() {
  float distance = 1.0 - texture2D(texture0, uv).a;
  float alpha = 1.0 - smoothstep(uWidth, uWidth + uEdge, distance);

  float distanceOutline = 1.0 - texture2D(texture0, uv + uOutlineOffset).a;
  float alphaOutline = 1.0 - smoothstep(uOutlineWidth, uOutlineWidth + uOutlineEdge, distanceOutline);

  float overallAlpha = alpha + (1.0 - alpha) * alphaOutline;
  vec3 overallColor = mix(uOutlineColor, uColor, alpha / overallAlpha);

  gl_FragColor = vec4(overallColor, overallAlpha);
}