#define SDF_PX 8.0
#define EDGE_GAMMA 0.105
#define FONT_SIZE 48.0
uniform sampler2D u_sdf_map;
uniform float u_gamma_scale : 0.5;
// uniform float u_font_size : 24.0;
uniform float u_opacity : 1.0;
uniform vec4 u_stroke_color : [0, 0, 0, 1];
uniform float u_stroke_width : 2.0;
uniform float u_halo_blur : 0.5;
uniform float u_DevicePixelRatio;

varying vec4 v_color;
varying vec2 v_uv;
varying float v_gamma_scale;
varying float v_fontScale;

varying mat4 styleMappingMat; // 传递从片元中传递的映射数据

#pragma include "picking"
void main() {
  // get style data mapping
  float opacity = styleMappingMat[0][0];
  float strokeWidth = styleMappingMat[0][2];
  vec4 textrueStroke = vec4(
    styleMappingMat[1][0],
    styleMappingMat[1][1],
    styleMappingMat[1][2],
    styleMappingMat[1][3]
  );

  // get sdf from atlas
  float dist = texture2D(u_sdf_map, v_uv).a;

  // float fontScale = u_font_size / FONT_SIZE;

  // lowp float buff = (6.0 - u_stroke_width / v_fontScale) / SDF_PX;
  lowp float buff = (6.0 - strokeWidth / v_fontScale) / SDF_PX;
  highp float gamma = (u_halo_blur * 1.19 / SDF_PX + EDGE_GAMMA) / (v_fontScale * u_gamma_scale) / 1.0;

  highp float gamma_scaled = gamma * v_gamma_scale;

  highp float alpha = smoothstep(buff - gamma_scaled, buff + gamma_scaled, dist);
  // gl_FragColor = mix(vec4(v_color.rgb, v_color.a * u_opacity), vec4(u_stroke_color.rgb, u_stroke_color.a * u_opacity), smoothstep(0., 0.5, 1. - dist));
  gl_FragColor = mix(vec4(v_color.rgb, v_color.a * opacity), vec4(textrueStroke.rgb, textrueStroke.a * opacity), smoothstep(0., 0.5, 1. - dist));
  gl_FragColor.a= gl_FragColor.a * alpha;
   // 作为 mask 模板时需要丢弃透明的像素
  if (gl_FragColor.a < 0.01) {
    discard;
  }
  gl_FragColor = filterColor(gl_FragColor);
}