/* -------------------- Interface -----------------------------------------------
Interface section included here simply because it is used by default in GeDoSaTo.  This is not part of the original film grain shader
*/
texture2D thisframeTex;

static float2 rcpres = PIXEL_SIZE;

const float timer;

#ifndef USE_SRGB
#define USE_SRGB true
#endif

sampler s0 = sampler_state
{
    texture = <thisframeTex>;
    AddressU = CLAMP;
    AddressV = CLAMP;
    MINFILTER = LINEAR;
    MAGFILTER = LINEAR;
    SRGBTexture = USE_SRGB;
};

struct VSOUT
{
    float4 vertPos : POSITION;
    float2 UVCoord : TEXCOORD0;
};

struct VSIN
{
    float4 vertPos : POSITION0;
    float2 UVCoord : TEXCOORD0;
};

VSOUT FrameVS(VSIN IN)
{
    VSOUT OUT;
    OUT.vertPos = IN.vertPos;
    OUT.UVCoord = IN.UVCoord;
    return OUT;
}

//----GRAIN----

#define USE_GRAIN             0 //[0 or 1] Film Grain: Adds an active graininess to the image.  Helps with banding and can add the illusion of detail

// Grain Settings
    #define GrainPower   0.05 //[0.00 to 1.00] Intensity of applied grain
    #define GrainColored   0 //[0 or 1] Whether grain should be colored or not
    #define GrainColorAmount   0.6//[0.00 to 1.00] Amount of color to add to grain
    #define GrainSize   1.6//[1.50 to 2.50] Size of individual pieces of grain
    #define GrainLuma   1.0//[0.00 to 1.00] Grain brightness

/* ------------------------- Grain --------------------------------------------
*/

static const float permTexUnit = 1.0/256.0;        // Perm texture texel-size
static const float permTexUnitHalf = 0.5/256.0;    // Half perm texture texel-size

float width = SCREEN_SIZE.x;
float height = SCREEN_SIZE.y;

static const float grainamount = GrainPower;
float colored = GrainColored;
float coloramount = GrainColorAmount;
float grainsize = GrainSize;
float lumamount = GrainLuma;

float fract (float inp)                 //GeDoSato did not (to my knowledge) have a fract function, so I implemented one.
{
    return (inp-floor(inp));
}

float4 mix (float x, float y, float a)          //GeDoSaTo did not to my knowledge have a mix function either, so I implemented one.
{
    return x * (1 - a) + y * a;
}

// a random texture generator, but you can also use a pre-computed perturbation texture
float4 rnm(in float2 tc)
{
    float noise = sin(dot(float3(tc.x, tc.y, timer), float3(12.9898, 78.233, 0.0025216))) * 43758.5453;

    float noiseR =  frac(noise)*2.0-1.0;
    float noiseG =  frac(noise*1.2154)*2.0-1.0;
    float noiseB =  frac(noise*1.3453)*2.0-1.0;
    float noiseA =  frac(noise*1.3647)*2.0-1.0;

    return float4(noiseR,noiseG,noiseB,noiseA);
}

float fade(in float t) {
    return t*t*t*(t*(t*6.0-15.0)+10.0);
}

float pnoise3D(in float3 p)
{
    float3 pi = permTexUnit*floor(p)+permTexUnitHalf; // Integer part, scaled so +1 moves permTexUnit texel
    // and offset 1/2 texel to sample texel centers
    float3 pf = frac(p);     // Fractional part for interpolation

    // Noise contributions from (x=0, y=0), z=0 and z=1
    float perm00 = rnm(pi.xy).a ;
    float3  grad000 = rnm(float2(perm00, pi.z)).rgb * 4.0 - 1.0;
    float n000 = dot(grad000, pf);
    float3  grad001 = rnm(float2(perm00, pi.z + permTexUnit)).rgb * 4.0 - 1.0;
    float n001 = dot(grad001, pf - float3(0.0, 0.0, 1.0));

    // Noise contributions from (x=0, y=1), z=0 and z=1
    float perm01 = rnm(pi.xy + float2(0.0, permTexUnit)).a ;
    float3  grad010 = rnm(float2(perm01, pi.z)).rgb * 4.0 - 1.0;
    float n010 = dot(grad010, pf - float3(0.0, 1.0, 0.0));
    float3  grad011 = rnm(float2(perm01, pi.z + permTexUnit)).rgb * 4.0 - 1.0;
    float n011 = dot(grad011, pf - float3(0.0, 1.0, 1.0));

    // Noise contributions from (x=1, y=0), z=0 and z=1
    float perm10 = rnm(pi.xy + float2(permTexUnit, 0.0)).a ;
    float3  grad100 = rnm(float2(perm10, pi.z)).rgb * 4.0 - 1.0;
    float n100 = dot(grad100, pf - float3(1.0, 0.0, 0.0));
    float3  grad101 = rnm(float2(perm10, pi.z + permTexUnit)).rgb * 4.0 - 1.0;
    float n101 = dot(grad101, pf - float3(1.0, 0.0, 1.0));

    // Noise contributions from (x=1, y=1), z=0 and z=1
    float perm11 = rnm(pi.xy + float2(permTexUnit, permTexUnit)).a ;
    float3  grad110 = rnm(float2(perm11, pi.z)).rgb * 4.0 - 1.0;
    float n110 = dot(grad110, pf - float3(1.0, 1.0, 0.0));
    float3  grad111 = rnm(float2(perm11, pi.z + permTexUnit)).rgb * 4.0 - 1.0;
    float n111 = dot(grad111, pf - float3(1.0, 1.0, 1.0));

    // Blend contributions along x
    float4 n_x = lerp(float4(n000, n001, n010, n011), float4(n100, n101, n110, n111), fade(pf.x));

    // Blend contributions along y
    float2 n_xy = lerp(n_x.xy, n_x.zw, fade(pf.y));

    // Blend contributions along z
    float n_xyz = lerp(n_xy.x, n_xy.y, fade(pf.z));

    // We're done, return the final noise value.
    return n_xyz;
}

//2d coordinate orientation thing
float2 coordRot(in float2 tc, in float angle)
{
    float aspectr = width/height;
    float rotX = ((tc.x*2.0-1.0)*aspectr*cos(angle)) - ((tc.y*2.0-1.0)*sin(angle));
    float rotY = ((tc.y*2.0-1.0)*cos(angle)) + ((tc.x*2.0-1.0)*aspectr*sin(angle));
    rotX = ((rotX/aspectr)*0.5+0.5);
    rotY = rotY*0.5+0.5;
    return float2(rotX,rotY);
}

float4 GrainPass( float4 colorInput, float2 tex )
{
    float3 rotOffset = float3(1.425,3.892,5.835); //rotation offset values
    float2 rotCoordsR = coordRot(tex, timer + rotOffset.x);
    float2 rot = rotCoordsR*float2(width/grainsize,height/grainsize);
    float pNoise = pnoise3D(float3(rot.x,rot.y,0.0));
    float3 noise = float3(pNoise, pNoise, pNoise);

    if (colored == 1)
    {
        float2 rotCoordsG = coordRot(tex, timer + rotOffset.y);
        float2 rotCoordsB = coordRot(tex, timer + rotOffset.z);
        noise.g = lerp(noise.r,pnoise3D(float3(rotCoordsG*float2(width/grainsize,height/grainsize),1.0)),coloramount);
        noise.b = lerp(noise.r,pnoise3D(float3(rotCoordsB*float2(width/grainsize,height/grainsize),2.0)),coloramount);
    }

    float3 col = colorInput.rgb;

    //noisiness response curve based on scene luminance
    float3 lumcoeff = float3(0.299,0.587,0.114);
    float luminance = lerp(0.0,dot(col, lumcoeff),lumamount);
    float lum = smoothstep(0.2,0.0,luminance);
    lum += luminance;

    float2 thepow = pow(lum, 4.0);

    noise = lerp(noise,float3(0.0, 0.0, 0.0),pow(lum,4.0));
    col += noise*grainamount;

    return float4(col,1.0);
}