/*
   Hyllian's jinc windowed-jinc 2-lobe sharper with anti-ringing Shader
   
   Copyright (C) 2011-2016 Hyllian/Jararaca - sergiogdb@gmail.com

   Permission is hereby granted, free of charge, to any person obtaining a copy
   of this software and associated documentation files (the "Software"), to deal
   in the Software without restriction, including without limitation the rights
   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   copies of the Software, and to permit persons to whom the Software is
   furnished to do so, subject to the following conditions:

   The above copyright notice and this permission notice shall be included in
   all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   THE SOFTWARE.

*/

#define JINC2_WINDOW_SINC 0.42
#define JINC2_SINC 0.92
#define JINC2_AR_STRENGTH 0.8

#define texCoord TEX0

#if defined(VERTEX)

#if __VERSION__ >= 130
#define OUT out
#define IN  in
#define tex2D texture
#else
#define OUT varying
#define IN attribute
#define tex2D texture2D
#endif

#ifdef GL_ES
#define COMPAT_PRECISION mediump
#else
#define COMPAT_PRECISION
#endif

IN  vec4 VertexCoord;
IN  vec4 Color;
IN  vec2 TexCoord;
OUT vec4 color;
OUT vec2 texCoord;

uniform mat4 MVPMatrix;
uniform COMPAT_PRECISION int  FrameDirection;
uniform COMPAT_PRECISION int  FrameCount;
uniform COMPAT_PRECISION vec2 OutputSize;
uniform COMPAT_PRECISION vec2 TextureSize;
uniform COMPAT_PRECISION vec2 InputSize;

void main()
{
    gl_Position = MVPMatrix * VertexCoord;
    color = Color;
    texCoord = TexCoord * 1.0001;
}

#elif defined(FRAGMENT)

#if __VERSION__ >= 130
#define IN in
#define tex2D texture
out vec4 FragColor;
#else
#define IN varying
#define FragColor gl_FragColor
#define tex2D texture2D
#endif

#ifdef GL_ES
#ifdef GL_FRAGMENT_PRECISION_HIGH
precision highp float;
#else
precision mediump float;
#endif
#define COMPAT_PRECISION mediump
#else
#define COMPAT_PRECISION
#endif

uniform COMPAT_PRECISION int FrameDirection;
uniform COMPAT_PRECISION int FrameCount;
uniform COMPAT_PRECISION vec2 OutputSize;
uniform COMPAT_PRECISION vec2 TextureSize;
uniform COMPAT_PRECISION vec2 InputSize;
uniform sampler2D s_p;
IN vec2 texCoord;

const   float halfpi            = 1.5707963267948966192313216916398;
const   float pi                = 3.1415926535897932384626433832795;
const   float wa                = JINC2_WINDOW_SINC*pi;
const   float wb                = JINC2_SINC*pi;

// Calculates the distance between two points
float d(vec2 pt1, vec2 pt2)
{
  vec2 v = pt2 - pt1;
  return sqrt(dot(v,v));
}

vec3 min4(vec3 a, vec3 b, vec3 c, vec3 d)
{
    return min(a, min(b, min(c, d)));
}

vec3 max4(vec3 a, vec3 b, vec3 c, vec3 d)
{
    return max(a, max(b, max(c, d)));
}

vec4 resampler(vec4 x)
{
   vec4 res;

    res.x = (x.x==0.0) ?  wa*wb  :  sin(x.x*wa)*sin(x.x*wb)/(x.x*x.x);
    res.y = (x.y==0.0) ?  wa*wb  :  sin(x.y*wa)*sin(x.y*wb)/(x.y*x.y);
    res.z = (x.z==0.0) ?  wa*wb  :  sin(x.z*wa)*sin(x.z*wb)/(x.z*x.z);
    res.w = (x.w==0.0) ?  wa*wb  :  sin(x.w*wa)*sin(x.w*wb)/(x.w*x.w);

   return res;
}

void main()
{

    vec3 color;
    vec4 weights[4];

    vec2 dx = vec2(1.0, 0.0);
    vec2 dy = vec2(0.0, 1.0);

    vec2 pc = texCoord*TextureSize;

    vec2 tc = (floor(pc-vec2(0.5,0.5))+vec2(0.5,0.5));
     
    weights[0] = resampler(vec4(d(pc, tc    -dx    -dy), d(pc, tc           -dy), d(pc, tc    +dx    -dy), d(pc, tc+2.0*dx    -dy)));
    weights[1] = resampler(vec4(d(pc, tc    -dx       ), d(pc, tc              ), d(pc, tc    +dx       ), d(pc, tc+2.0*dx       )));
    weights[2] = resampler(vec4(d(pc, tc    -dx    +dy), d(pc, tc           +dy), d(pc, tc    +dx    +dy), d(pc, tc+2.0*dx    +dy)));
    weights[3] = resampler(vec4(d(pc, tc    -dx+2.0*dy), d(pc, tc       +2.0*dy), d(pc, tc    +dx+2.0*dy), d(pc, tc+2.0*dx+2.0*dy)));

    dx = dx/TextureSize;
    dy = dy/TextureSize;
    tc = tc/TextureSize;

    vec3 c00 = tex2D(s_p, tc    -dx    -dy).xyz;
    vec3 c10 = tex2D(s_p, tc           -dy).xyz;
    vec3 c20 = tex2D(s_p, tc    +dx    -dy).xyz;
    vec3 c30 = tex2D(s_p, tc+2.0*dx    -dy).xyz;
    vec3 c01 = tex2D(s_p, tc    -dx       ).xyz;
    vec3 c11 = tex2D(s_p, tc              ).xyz;
    vec3 c21 = tex2D(s_p, tc    +dx       ).xyz;
    vec3 c31 = tex2D(s_p, tc+2.0*dx       ).xyz;
    vec3 c02 = tex2D(s_p, tc    -dx    +dy).xyz;
    vec3 c12 = tex2D(s_p, tc           +dy).xyz;
    vec3 c22 = tex2D(s_p, tc    +dx    +dy).xyz;
    vec3 c32 = tex2D(s_p, tc+2.0*dx    +dy).xyz;
    vec3 c03 = tex2D(s_p, tc    -dx+2.0*dy).xyz;
    vec3 c13 = tex2D(s_p, tc       +2.0*dy).xyz;
    vec3 c23 = tex2D(s_p, tc    +dx+2.0*dy).xyz;
    vec3 c33 = tex2D(s_p, tc+2.0*dx+2.0*dy).xyz;

    color = tex2D(s_p, texCoord).xyz;

    //  Get min/max samples
    vec3 min_sample = min4(c11, c21, c12, c22);
    vec3 max_sample = max4(c11, c21, c12, c22);
/*
      color = mat4x3(c00, c10, c20, c30) * weights[0];
      color+= mat4x3(c01, c11, c21, c31) * weights[1];
      color+= mat4x3(c02, c12, c22, c32) * weights[2];
      color+= mat4x3(c03, c13, c23, c33) * weights[3];
      mat4 wgts = mat4(weights[0], weights[1], weights[2], weights[3]);
      vec4 wsum = wgts * vec4(1.0,1.0,1.0,1.0);
      color = color/(dot(wsum, vec4(1.0,1.0,1.0,1.0)));
*/


    color = vec3(dot(weights[0], vec4(c00.x, c10.x, c20.x, c30.x)), dot(weights[0], vec4(c00.y, c10.y, c20.y, c30.y)), dot(weights[0], vec4(c00.z, c10.z, c20.z, c30.z)));
    color+= vec3(dot(weights[1], vec4(c01.x, c11.x, c21.x, c31.x)), dot(weights[1], vec4(c01.y, c11.y, c21.y, c31.y)), dot(weights[1], vec4(c01.z, c11.z, c21.z, c31.z)));
    color+= vec3(dot(weights[2], vec4(c02.x, c12.x, c22.x, c32.x)), dot(weights[2], vec4(c02.y, c12.y, c22.y, c32.y)), dot(weights[2], vec4(c02.z, c12.z, c22.z, c32.z)));
    color+= vec3(dot(weights[3], vec4(c03.x, c13.x, c23.x, c33.x)), dot(weights[3], vec4(c03.y, c13.y, c23.y, c33.y)), dot(weights[3], vec4(c03.z, c13.z, c23.z, c33.z)));
    color = color/(dot(weights[0], vec4(1,1,1,1)) + dot(weights[1], vec4(1,1,1,1)) + dot(weights[2], vec4(1,1,1,1)) + dot(weights[3], vec4(1,1,1,1)));

    // Anti-ringing
    vec3 aux = color;
    color = clamp(color, min_sample, max_sample);
    color = mix(aux, color, JINC2_AR_STRENGTH);

    // final sum and weight normalization
    FragColor.xyz = color;
}
#endif
