/*
   SimoneT AA Shader v 1.0

   Copyright (C) 2016 SimoneT - simone1tarditi@gmail.com

   part of the code taken from "Directional Cubic Convolution Interpolation"
   created by Dengwen Zhou and Xiaoliu Shen.

   https://en.wikipedia.org/wiki/Directional_Cubic_Convolution_Interpolation

   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.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/

uniform sampler2D OGL2Texture;
uniform vec4 OGL2Size;
uniform vec4 OGL2InvSize;
uniform vec4 OGL2Param;

const   vec2 Size3D    = vec2( 4096, 2048 );
const   vec2 InvSize3D = vec2(1.0/4096,1.0/2048);
const   vec3 ones = vec3(1.0);
const	vec4 exp = vec4(30.0);	

float Cdistance(vec3 c1, vec3 c2){

	return dot(abs(c1 - c2),ones);

}
 
vec3 Interpolate( vec3 a, vec3 b, vec3 c, vec3 d ) {

	return (( a + b ) * 10.0 +  c + d ) / 22.0;

}

vec3 STAA( vec2 coord, vec2 texSize, vec2 shift ) {

	vec2 TexCoord = (floor(coord*texSize)+0.5)*shift;

	vec3 C00 = texture2D(OGL2Texture, TexCoord - shift * 2.0            ).rgb;
	vec3 C01 = texture2D(OGL2Texture, TexCoord - shift * vec2( 1.0, 2.0)).rgb;
	vec3 C02 = texture2D(OGL2Texture, TexCoord - shift * vec2( 0.0, 2.0)).rgb;
	vec3 C03 = texture2D(OGL2Texture, TexCoord - shift * vec2(-1.0, 2.0)).rgb;
	vec3 C04 = texture2D(OGL2Texture, TexCoord - shift * vec2(-2.0, 2.0)).rgb;

	vec3 C05 = texture2D(OGL2Texture, TexCoord - shift * vec2( 2.0, 1.0)).rgb;
	vec3 C06 = texture2D(OGL2Texture, TexCoord - shift                  ).rgb;
	vec3 C07 = texture2D(OGL2Texture, TexCoord - shift * vec2( 0.0, 1.0)).rgb;
	vec3 C08 = texture2D(OGL2Texture, TexCoord - shift * vec2(-1.0, 1.0)).rgb;
	vec3 C09 = texture2D(OGL2Texture, TexCoord - shift * vec2(-2.0, 1.0)).rgb;

	vec3 C10 = texture2D(OGL2Texture, TexCoord - shift * vec2( 2.0, 0.0)).rgb;
	vec3 C11 = texture2D(OGL2Texture, TexCoord - shift * vec2( 1.0, 0.0)).rgb;
	vec3 C12 = texture2D(OGL2Texture, TexCoord                          ).rgb;
	vec3 C13 = texture2D(OGL2Texture, TexCoord + shift * vec2( 1.0, 0.0)).rgb;
	vec3 C14 = texture2D(OGL2Texture, TexCoord + shift * vec2( 2.0, 0.0)).rgb;

	vec3 C15 = texture2D(OGL2Texture, TexCoord + shift * vec2(-2.0, 1.0)).rgb;
	vec3 C16 = texture2D(OGL2Texture, TexCoord + shift * vec2(-1.0, 1.0)).rgb;
	vec3 C17 = texture2D(OGL2Texture, TexCoord + shift * vec2( 0.0, 1.0)).rgb;
	vec3 C18 = texture2D(OGL2Texture, TexCoord + shift                  ).rgb;
	vec3 C19 = texture2D(OGL2Texture, TexCoord + shift * vec2( 2.0, 1.0)).rgb;

	vec3 C20 = texture2D(OGL2Texture, TexCoord + shift * vec2(-2.0, 2.0)).rgb;
	vec3 C21 = texture2D(OGL2Texture, TexCoord + shift * vec2(-1.0, 2.0)).rgb;
	vec3 C22 = texture2D(OGL2Texture, TexCoord + shift * vec2( 0.0, 2.0)).rgb;
	vec3 C23 = texture2D(OGL2Texture, TexCoord + shift * vec2( 1.0, 2.0)).rgb;
	vec3 C24 = texture2D(OGL2Texture, TexCoord + shift * 2.0            ).rgb;

	float C03C09 = Cdistance(C03,C09);
	float C02C08 = Cdistance(C02,C08);
	float C08C14 = Cdistance(C08,C14);
	float C01C07 = Cdistance(C01,C07);
	float C07C13 = Cdistance(C07,C13);
	float C13C19 = Cdistance(C13,C19);
	float C00C06 = Cdistance(C00,C06);
	float C06C12 = Cdistance(C06,C12);
	float C12C18 = Cdistance(C12,C18);
	float C18C24 = Cdistance(C18,C24);
	float C05C11 = Cdistance(C05,C11);
	float C11C17 = Cdistance(C11,C17);
	float C17C23 = Cdistance(C17,C23);
	float C10C16 = Cdistance(C10,C16);
	float C16C22 = Cdistance(C16,C22);
	float C15C21 = Cdistance(C15,C21);

	vec4 d01 = vec4(
	C02C08 + C01C07 + C07C13 + C00C06 + C06C12 + C12C18 + C05C11 + C11C17 + C10C16,
	C03C09 + C02C08 + C08C14 + C01C07 + C07C13 + C13C19 + C06C12 + C12C18 + C11C17,
	C07C13 + C06C12 + C12C18 + C05C11 + C11C17 + C17C23 + C10C16 + C16C22 + C15C21,
	C08C14 + C07C13 + C13C19 + C06C12 + C12C18 + C18C24 + C11C17 + C17C23 + C16C22);

	d01 = pow(d01,exp)+1.0;

	float C01C05 = Cdistance(C01,C05);
	float C02C06 = Cdistance(C02,C06);
	float C06C10 = Cdistance(C06,C10);
	float C03C07 = Cdistance(C03,C07);
	float C07C11 = Cdistance(C07,C11);
	float C11C15 = Cdistance(C11,C15);
	float C04C08 = Cdistance(C04,C08);
	float C08C12 = Cdistance(C08,C12);
	float C12C16 = Cdistance(C12,C16);
	float C16C20 = Cdistance(C16,C20);
	float C09C13 = Cdistance(C09,C13);
	float C13C17 = Cdistance(C13,C17);
	float C17C21 = Cdistance(C17,C21);
	float C14C18 = Cdistance(C14,C18);
	float C18C22 = Cdistance(C18,C22);
	float C19C23 = Cdistance(C19,C23);

	vec4 d02 = vec4(
	C01C05 + C02C06 + C06C10 + C03C07 + C07C11 + C11C15 + C08C12 + C12C16 + C13C17,
	C02C06 + C03C07 + C07C11 + C04C08 + C08C12 + C12C16 + C09C13 + C13C17 + C14C18,
	C06C10 + C07C11 + C11C15 + C08C12 + C12C16 + C16C20 + C13C17 + C17C21 + C18C22,
	C07C11 + C08C12 + C12C16 + C09C13 + C13C17 + C17C21 + C14C18 + C18C22 + C19C23);

	d02 = pow(d02,exp)+1.0;

	vec4 w01 = 1.0 / d01;
	vec4 w02 = 1.0 / d02;
	vec4 w03 = w01 + w02;
	     w03 = 1.0 / w03;

	vec4 weight01 = w01 * w03;
	vec4 weight02 = w02 * w03;

	vec3 DR0 = Interpolate( C06, C12, C00, C18 ); 
	vec3 UR0 = Interpolate( C07, C11, C03, C15 ); 

	vec3 DR1 = Interpolate( C07, C13, C01, C19 ); 
	vec3 UR1 = Interpolate( C08, C12, C04, C16 ); 

	vec3 DR2 = Interpolate( C11, C17, C05, C23 ); 
	vec3 UR2 = Interpolate( C12, C16, C08, C20 ); 

	vec3 DR3 = Interpolate( C12, C18, C06, C24 ); 
	vec3 UR3 = Interpolate( C13, C17, C09, C21 ); 

	vec2 frac1 = fract(gl_TexCoord[0].xy*texSize);

	vec3 sum0 = DR0 * weight01.x + UR0 * weight02.x; 
	vec3 sum1 = DR1 * weight01.y + UR1 * weight02.y;
	vec3 sum2 = DR2 * weight01.z + UR2 * weight02.z;
	vec3 sum3 = DR3 * weight01.w + UR3 * weight02.w;

	return mix(mix(sum0,sum1,frac1.x),mix(sum2,sum3,frac1.x),frac1.y);

}

void main()
{
 
	gl_FragColor.rgb = STAA( gl_TexCoord[0].xy, Size3D, InvSize3D );

}
