uniform sampler2D colormap;
varying highp vec2 vTexCoords;
uniform vec2 dimensions;

// Basic FXAA implementation based on the code on geeks3d.com 
#define FXAA_REDUCE_MIN (1.0/ 128.0)
#define FXAA_REDUCE_MUL (1.0 / 8.0)
#define FXAA_SPAN_MAX 8.0

vec4 applyFXAA(vec2 fragCoord, sampler2D tex)
{
    vec4 color;
    vec2 inverseVP = vec2(1.0 / dimensions.x, 1.0 / dimensions.y);
    vec3 rgbNW = texture2D(tex, fragCoord + vec2(-1.0, -1.0) * inverseVP).xyz;
    vec3 rgbNE = texture2D(tex, fragCoord + vec2(1.0, -1.0) * inverseVP).xyz;
    vec3 rgbSW = texture2D(tex, fragCoord + vec2(-1.0, 1.0) * inverseVP).xyz;
    vec3 rgbSE = texture2D(tex, fragCoord + vec2(1.0, 1.0) * inverseVP).xyz;
    vec3 rgbM  = texture2D(tex, fragCoord  * inverseVP).xyz;
    vec3 luma = vec3(0.299, 0.587, 0.114);
    float lumaNW = dot(rgbNW, luma);
    float lumaNE = dot(rgbNE, luma);
    float lumaSW = dot(rgbSW, luma);
    float lumaSE = dot(rgbSE, luma);
    float lumaM  = dot(rgbM,  luma);
    float lumaMin = min(lumaM, min(min(lumaNW, lumaNE), min(lumaSW, lumaSE)));
    float lumaMax = max(lumaM, max(max(lumaNW, lumaNE), max(lumaSW, lumaSE)));

    vec2 dir;
    dir.x = -((lumaNW + lumaNE) - (lumaSW + lumaSE));
    dir.y =  ((lumaNW + lumaSW) - (lumaNE + lumaSE));

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

    float rcpDirMin = 1.0 / (min(abs(dir.x), abs(dir.y)) + dirReduce);
    dir = min(vec2(FXAA_SPAN_MAX, FXAA_SPAN_MAX),
            max(vec2(-FXAA_SPAN_MAX, -FXAA_SPAN_MAX),
            dir * rcpDirMin)) * inverseVP;

    vec3 rgbA = 0.5 * (
        texture2D(tex, fragCoord + dir * (1.0 / 3.0 - 0.5)).xyz +
        texture2D(tex, fragCoord  + dir * (2.0 / 3.0 - 0.5)).xyz);
    vec3 rgbB = rgbA * 0.5 + 0.25 * (
        texture2D(tex, fragCoord  + dir * -0.5).xyz +
        texture2D(tex, fragCoord  + dir * 0.5).xyz);

    float lumaB = dot(rgbB, luma);
    if ((lumaB < lumaMin) || (lumaB > lumaMax))
        color = vec4(rgbA, 1.0);
    else
        color = vec4(rgbB, 1.0);
    return color;
}
//DEFINEFRAGCOLOR
void main (void) {
   gl_FragColor = applyFXAA(vTexCoords, colormap);
}