#version 450


// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 2 of the License, or (at your option)
// any later version.


layout(push_constant) uniform Push
{
    vec4 SourceSize;
    vec4 OriginalSize;
    vec4 OutputSize;
    uint FrameCount;
  float CURV;
  float SCAN;
  float MASK;
  float LUM;
  float INTERL;
  float SAT, LANC;
} params;

// Parameter lines go here:

#pragma parameter CURV "CRT-Geom Curvature" 1.0 0.0 1.0 1.0
#pragma parameter SCAN "CRT-Geom Scanline Weight" 0.25 0.2 0.6 0.05
#pragma parameter MASK "CRT-Geom Dotmask Strength" 0.15 0.0 0.5 0.05
#pragma parameter LUM "CRT-Geom Luminance" 0.05 0.0 0.5 0.01
#pragma parameter INTERL "CRT-Geom Interlacing Simulation" 1.0 0.0 1.0 1.0
#pragma parameter SAT "CRT-Geom Saturation" 1.1 0.0 2.0 0.01
#pragma parameter LANC "Filter profile: Accurate/Fast" 0.0 0.0 1.0 1.0

#define PI 3.1415926535897932384626433
#define SourceSize params.SourceSize
#define OriginalSize params.OriginalSize
#define OutputSize params.OutputSize
#define FrameCount params.FrameCount

#define CURV params.CURV
#define SCAN params.SCAN
#define MASK params.MASK
#define LUM params.LUM
#define INTERL params.INTERL
#define SAT params.SAT
#define LANC params.LANC
layout(std140, set = 0, binding = 0) uniform UBO
{
    mat4 MVP;
} global;

#pragma stage vertex
layout(location = 0) in vec4 Position;
layout(location = 1) in vec2 TexCoord;
layout(location = 0) out vec2 vTexCoord;
layout(location = 1) out vec2 scale;
layout(location = 2) out vec2 warpp;
layout(location = 3) out vec2 warp;
layout(location = 4) out float fragpos;

void main()
{
    gl_Position = global.MVP * Position;
    vTexCoord = TexCoord * 1.0001;
    scale = SourceSize.xy/OriginalSize.xy;
    warpp = vTexCoord.xy*scale;   
    fragpos = warpp.x*OutputSize.x*PI;
    warp = warpp*2.0-1.0;   
}

#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
layout(location = 0) out vec4 FragColor;
layout(location = 1) in vec2 scale;
layout(location = 2) in vec2 warpp;
layout(location = 3) in vec2 warp;
layout(location = 4) in float fragpos;

layout(set = 0, binding = 1) uniform sampler2D Source;

float scan(float pos, vec3 color)
    {
    float wid = SCAN + 0.1 * max(max(color.r,color.g),color.b);
    float weight = pos / wid;
    return  LUM + (0.1 + SCAN) * exp(-weight * weight ) / wid;
    }

vec2 Warp(vec2 pos)
{
    pos = warp;
    pos *= vec2(1.0+pos.y*pos.y*0.031, 1.0+pos.x*pos.x*0.05);
    pos = pos*0.5+0.5;
    return pos;
}

void main()
{
    vec2 pos;
    if (CURV == 1.0) pos = Warp(warpp);
    else pos = vTexCoord;

    vec2 corn   = min(pos,1.0-pos); // This is used to mask the rounded
         corn.x = 0.0001/corn.x;  // corners later on

    if (CURV == 1.0) pos /= scale;

// Lanczos 2
    // Source position in fractions of a texel
    vec2 src_pos = pos*SourceSize.xy;
    // Source bottom left texel centre
    vec2 src_centre = floor(src_pos - 0.5) + 0.5;
    // f is position. f.x runs left to right, y bottom to top, z right to left, w top to bottom
    vec4 f; 
    f.xy = src_pos - src_centre;
    f.zw = 1.0 - f.xy;
    // Calculate weights in x and y in parallel.
    // These polynomials are piecewise approximation of Lanczos kernel
    // Calculator here: https://gist.github.com/going-digital/752271db735a07da7617079482394543
 vec4 l2_w0_o3, l2_w1_o3;
    if (LANC == 0.0)
     {l2_w0_o3 = (((1.5672) * f - 2.6445) * f + 0.0837) * f + 0.9976;
      l2_w1_o3 = (((-0.7389) * f + 1.3652) * f - 0.6295) * f - 0.0004;}
    else  {l2_w0_o3 = (-1.1828) * f + 1.1298;
           l2_w1_o3 = (0.0858) * f - 0.0792;}


    vec4 w1_2  = l2_w0_o3;
    vec2 w12   = w1_2.xy + w1_2.zw;
    vec4 wedge = l2_w1_o3 * vec4 (w12.yx, w12.yx);

    // Calculate texture read positions. tc12 uses bilinear interpolation to do 4 reads in 1.
    vec2 tc12 = SourceSize.zw * (src_centre + w1_2.zw / w12);
    vec2 tc0  = SourceSize.zw * (src_centre - 1.0);
    vec2 tc3  = SourceSize.zw * (src_centre + 2.0);
    
    // Sharpening adjustment
    float sum = wedge.x + wedge.y + wedge.z + wedge.w + w12.x * w12.y;    
    wedge /= sum;

    vec3 res = vec3(
        texture(Source, vec2(tc12.x, tc0.y)).rgb * wedge.y +
        texture(Source, vec2(tc0.x, tc12.y)).rgb * wedge.x +
        texture(Source, tc12.xy).rgb * (w12.x * w12.y) +
        texture(Source, vec2(tc3.x, tc12.y)).rgb * wedge.z +
        texture(Source, vec2(tc12.x, tc3.y)).rgb * wedge.w
    );


    float fp = fract(src_pos.y-0.5);
    if (OriginalSize.y > 400.0) fp = fract(src_pos.y/2.0-0.5);

    if (INTERL == 1.0 && OriginalSize.y > 400.0) 
    {
    fp = mod(float(FrameCount),2.0) <1.0 ? 0.5+fp:fp;
    }

    float scn  = scan(fp,res) + scan(1.0-fp,res);
    float msk  = MASK*sin(fragpos)+1.0-MASK;
    res *= sqrt(scn*msk);

    float l = dot(vec3(0.29, 0.6, 0.11), res);
    res  = mix(vec3(l), res, SAT);

if (corn.y <= corn.x && CURV == 1.0 || corn.x < 0.0001 && CURV == 1.0 ) res = vec3(0.0);

    FragColor = vec4(res,1.0);
}