CCEffect %{
  techniques:
  - passes:
    - vert: vs
      frag: fs
      blendState:
        targets:
        - blend: true
          blendSrc: src_alpha
          blendDst: one_minus_src_alpha
          blendSrcAlpha: one
          blendDstAlpha: one_minus_src_alpha
      rasterizerState:
        cullMode: none
      depthStencilState:
        depthTest: false
        depthWrite: false
      properties:
        texture: { value: white }
        imageSize: { value: [224, 43] }
        outlineWidth: { value: 2 }
        outlineColor: { value: [0, 0, 0, 0.5] }
}%

CCProgram vs %{
  precision highp float;
  #include <cc-global>
  #include <cc-local>
  in vec3 a_position;
  in vec4 a_color;
  in vec2 a_uv0;
  out vec4 v_color;
  out vec2 v_uv0;
  void main () {
    vec4 pos = vec4(a_position, 1.0);
    #if CC_USE_MODEL
      gl_Position = cc_matViewProj * cc_matWorld * pos;
    #else
      gl_Position = cc_matViewProj * pos;
    #endif
    v_color = a_color;
    v_uv0 = a_uv0;
  }
}%

CCProgram fs %{
  precision highp float;
  #include <texture>
  in vec4 v_color;
  in vec2 v_uv0;
  uniform sampler2D texture;
  uniform Outline {
    vec4 outlineColor;
    vec2 imageSize;
    float outlineWidth;
  };
  // This sprite uses a standalone, untrimmed texture with dynamic packing disabled.
  vec4 sampleAt (vec2 point) {
    vec2 uv = point / imageSize;
    if (uv.x < 0.0 || uv.y < 0.0 || uv.x > 1.0 || uv.y > 1.0) return vec4(0.0);
    vec4 color = vec4(1.0);
    CCTexture(texture, uv, color);
    return color;
  }
  void main () {
    // The authored quad reserves two pixels per side, keeping the original art at 224 x 43.
    vec2 point = v_uv0 * (imageSize + vec2(4.0)) - vec2(2.0);
    vec4 fill = sampleAt(point);
    float expanded = fill.a;
    for (int i = 0; i < 16; i++) {
      float angle = float(i) * 0.3926990817;
      vec2 offset = vec2(cos(angle), sin(angle)) * outlineWidth;
      expanded = max(expanded, sampleAt(point + offset).a);
    }
    // Composite the original art over a 50%-opaque outline, without accumulating opacity per sample.
    float border = expanded * outlineColor.a * (1.0 - fill.a);
    float alpha = fill.a + border;
    vec3 rgb = (fill.rgb * fill.a + outlineColor.rgb * border) / max(alpha, 0.00001);
    vec4 color = vec4(rgb * v_color.rgb, alpha * v_color.a);
    #if USE_BGRA
      gl_FragColor = color.bgra;
    #else
      gl_FragColor = color;
    #endif
  }
}%