ProjectArcade

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// PPSSPP: Grabbed from Processing and slightly modified.
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// FXAA shader, GLSL code adapted from:
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// http://horde3d.org/wiki/index.php5?title=Shading_Technique_-_FXAA
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// Whitepaper describing the technique:
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// http://developer.download.nvidia.com/assets/gamedev/files/sdk/11/FXAA_WhitePaper.pdf
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#ifdef GL_ES
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precision mediump float;
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precision mediump int;
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#endif
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uniform sampler2D sampler0;
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// The inverse of the texture dimensions along X and Y
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uniform vec2 u_texelDelta;
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varying vec2 v_texcoord0;
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void main() {
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  // The parameters are hardcoded for now, but could be
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  // made into uniforms to control fromt he program.
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  float FXAA_SPAN_MAX = 8.0;
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  float FXAA_REDUCE_MUL = 1.0/8.0;
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  float FXAA_REDUCE_MIN = (1.0/128.0);
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  vec3 rgbNW = texture2D(sampler0, v_texcoord0.xy + (vec2(-1.0, -1.0) * u_texelDelta)).xyz;
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  vec3 rgbNE = texture2D(sampler0, v_texcoord0.xy + (vec2(+1.0, -1.0) * u_texelDelta)).xyz;
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  vec3 rgbSW = texture2D(sampler0, v_texcoord0.xy + (vec2(-1.0, +1.0) * u_texelDelta)).xyz;
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  vec3 rgbSE = texture2D(sampler0, v_texcoord0.xy + (vec2(+1.0, +1.0) * u_texelDelta)).xyz;
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  vec3 rgbM  = texture2D(sampler0, v_texcoord0.xy).xyz;
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  vec3 luma = vec3(0.299, 0.587, 0.114);
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  float lumaNW = dot(rgbNW, luma);
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  float lumaNE = dot(rgbNE, luma);
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  float lumaSW = dot(rgbSW, luma);
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  float lumaSE = dot(rgbSE, luma);
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  float lumaM  = dot( rgbM, luma);
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  float lumaMin = min(lumaM, min(min(lumaNW, lumaNE), min(lumaSW, lumaSE)));
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  float lumaMax = max(lumaM, max(max(lumaNW, lumaNE), max(lumaSW, lumaSE)));
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  vec2 dir;
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  dir.x = -((lumaNW + lumaNE) - (lumaSW + lumaSE));
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  dir.y =  ((lumaNW + lumaSW) - (lumaNE + lumaSE));
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  float dirReduce = max((lumaNW + lumaNE + lumaSW + lumaSE) * (0.25 * FXAA_REDUCE_MUL), FXAA_REDUCE_MIN);
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  float rcpDirMin = 1.0/(min(abs(dir.x), abs(dir.y)) + dirReduce);
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  dir = min(vec2(FXAA_SPAN_MAX,  FXAA_SPAN_MAX), 
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        max(vec2(-FXAA_SPAN_MAX, -FXAA_SPAN_MAX), dir * rcpDirMin)) * u_texelDelta;
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  vec3 rgbA = (1.0/2.0) * (
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              texture2D(sampler0, v_texcoord0.xy + dir * (1.0/3.0 - 0.5)).xyz +
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              texture2D(sampler0, v_texcoord0.xy + dir * (2.0/3.0 - 0.5)).xyz);
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  vec3 rgbB = rgbA * (1.0/2.0) + (1.0/4.0) * (
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              texture2D(sampler0, v_texcoord0.xy + dir * (0.0/3.0 - 0.5)).xyz +
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              texture2D(sampler0, v_texcoord0.xy + dir * (3.0/3.0 - 0.5)).xyz);
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  float lumaB = dot(rgbB, luma);
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  if((lumaB < lumaMin) || (lumaB > lumaMax)){
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    gl_FragColor.xyz=rgbA;
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  } else {
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    gl_FragColor.xyz=rgbB;
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  }
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  gl_FragColor.a = 1.0;
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}
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