FXAA GLSL

 #version 300 es

precision mediump float;

out vec4 FragColor;

  

in vec2 TexCoords;

uniform sampler2D screenTexture;

uniform vec2 screenSize;

float FXAA_SPAN_MAX = 8.0f;

float FXAA_REDUCE_MUL = 1.0f/8.0f;

float FXAA_REDUCE_MIN = 1.0f/128.0f;

vec3 computeToneMapping(vec2 texCoords);

vec3 computeFxaa();

void main()

{

    const float gamma = 2.2;

vec3 hdrColor = computeFxaa();

// gamma correction

hdrColor = pow(hdrColor, vec3(1.0/gamma));

    

    float contrast = 1.5; // 增加对比度

    float brightness = 0.0; // 亮度偏移量

    hdrColor = (hdrColor - vec3(0.2)) * vec3(contrast) + vec3(brightness);

    

FragColor = vec4(hdrColor, 1.0);

}

vec3 computeToneMapping(vec2 texCoords)

{

const float exposure = 1.0;

vec3 hdrColor = texture(screenTexture, texCoords).xyz;

return vec3(1.0) - exp(-hdrColor * exposure);

}

vec3 computeFxaa()

{

    vec2 screenTextureOffset = 1.0 / screenSize;

    vec3 luma = vec3(0.299f, 0.587f, 0.114f);

    vec3 offsetNW = computeToneMapping(TexCoords.xy + (vec2(-1.0f, -1.0f) * screenTextureOffset));

    vec3 offsetNE = computeToneMapping(TexCoords.xy + (vec2(1.0f, -1.0f) * screenTextureOffset));

    vec3 offsetSW = computeToneMapping(TexCoords.xy + (vec2(-1.0f, 1.0f) * screenTextureOffset));

    vec3 offsetSE = computeToneMapping(TexCoords.xy + (vec2(1.0f, 1.0f) * screenTextureOffset));

    vec3 offsetM  = computeToneMapping(TexCoords.xy);

    float lumaNW = dot(luma, offsetNW);

    float lumaNE = dot(luma, offsetNE);

    float lumaSW = dot(luma, offsetSW);

    float lumaSE = dot(luma, offsetSE);

    float lumaM  = dot(luma, offsetNW);

    vec2 dir = vec2(-((lumaNW + lumaNE) - (lumaSW + lumaSE)), ((lumaNW + lumaSW) - (lumaNE + lumaSE)));

    float dirReduce = max((lumaNW + lumaNE + lumaSW + lumaSE) * (FXAA_REDUCE_MUL * 0.25f), FXAA_REDUCE_MIN);

    float dirCorrection = 1.0f / (min(abs(dir.x), abs(dir.y)) + dirReduce);

    dir = min(vec2(FXAA_SPAN_MAX), max(vec2(-FXAA_SPAN_MAX), dir * dirCorrection)) * screenTextureOffset;

    vec3 resultA = 0.5f * (computeToneMapping(TexCoords.xy + (dir * vec2(1.0f / 3.0f - 0.5f))) +

                                    computeToneMapping(TexCoords.xy + (dir * vec2(2.0f / 3.0f - 0.5f))));

    vec3 resultB = resultA * 0.5f + 0.25f * (computeToneMapping(TexCoords.xy + (dir * vec2(0.0f / 3.0f - 0.5f))).xyz +

                                             computeToneMapping(TexCoords.xy + (dir * vec2(3.0f / 3.0f - 0.5f))).xyz);

    float lumaMin = min(lumaM, min(min(lumaNW, lumaNE), min(lumaSW, lumaSE)));

    float lumaMax = max(lumaM, max(max(lumaNW, lumaNE), max(lumaSW, lumaSE)));

    float lumaResultB = dot(luma, resultB);

    if(lumaResultB < lumaMin || lumaResultB > lumaMax) {

return vec3(resultA);

}

return vec3(resultB);

}