package funkin.graphics.shaders;

import flixel.system.FlxAssets.FlxShader;

class AngleMask extends FlxShader
{
  @:glFragmentSource('
    #pragma header

    uniform vec2 endPosition;
    vec2 hash22(vec2 p) {
      vec3 p3 = fract(vec3(p.xyx) * vec3(.1031, .1030, .0973));
      p3 += dot(p3, p3.yzx + 33.33);
      return fract((p3.xx + p3.yz) * p3.zy);
    }



    // ====== GAMMA CORRECTION ====== //
    // Helps with color mixing -- good to have by default in almost any shader
    // See https://www.shadertoy.com/view/lscSzl
    vec3 gamma(in vec3 color) {
      return pow(color, vec3(1.0 / 2.2));
    }

    vec4 mainPass(vec2 fragCoord) {
      vec4 base = texture2D(bitmap, fragCoord);

      vec2 uv = fragCoord.xy;

      vec2 start = vec2(0.0, 0.0);
      vec2 end = vec2(endPosition.x / openfl_TextureSize.x, 1.0);

      float dx = end.x - start.x;
      float dy = end.y - start.y;

      float angle = atan(dy, dx);

      uv.x -= start.x;
      uv.y -= start.y;

      float uvA = atan(uv.y, uv.x);

      if (uvA < angle)
        return base;
      else
        return vec4(0.0);
    }

    vec4 antialias(vec2 fragCoord) {

      const float AA_STAGES = 2.0;

      const float AA_TOTAL_PASSES = AA_STAGES * AA_STAGES + 1.0;
      const float AA_JITTER = 0.5;

      // Run the shader multiple times with a random subpixel offset each time and average the results
      vec4 color = mainPass(fragCoord);
      for (float x = 0.0; x < AA_STAGES; x++)
      {
          for (float y = 0.0; y < AA_STAGES; y++)
          {
              vec2 offset = AA_JITTER * (2.0 * hash22(vec2(x, y)) - 1.0) / openfl_TextureSize.xy;
              color += mainPass(fragCoord + offset);
          }
      }
      return color / AA_TOTAL_PASSES;
    }

    void main() {
      vec4 col = antialias(openfl_TextureCoordv);
      // col.xyz = gamma(col.xyz);
      gl_FragColor = col;
    }')
  public function new()
  {
    super();

    endPosition.value = [90, 100]; // 100 AS DEFAULT WORKS NICELY FOR FREEPLAY?
  }
}