//
//  Phosphor shader - Copyright (C) 2011 caligari.
//
//  Ported by Hyllian.
//
//  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.
//
//  Taken from the RetroArch project and modified for ES-DE.
//

#if defined(VERTEX)

#if __VERSION__ >= 130
#define COMPAT_VARYING out
#define COMPAT_ATTRIBUTE in
#define COMPAT_TEXTURE texture
#else
#define COMPAT_VARYING varying
#define COMPAT_ATTRIBUTE attribute
#define COMPAT_TEXTURE texture2D
#endif

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

COMPAT_ATTRIBUTE vec4 VertexCoord;
COMPAT_ATTRIBUTE vec4 COLOR;
COMPAT_ATTRIBUTE vec4 TexCoord;
COMPAT_VARYING vec4 COL0;
COMPAT_VARYING vec4 TEX0;
COMPAT_VARYING vec2 onex;
COMPAT_VARYING vec2 oney;

vec4 _oPosition1;
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;

#define SourceSize vec4(TextureSize, 1.0 / TextureSize) // Either TextureSize or InputSize.

void main()
{
    gl_Position = MVPMatrix * gl_Vertex;
    COL0 = COLOR;
    TEX0.xy = gl_MultiTexCoord0.xy;
    onex = vec2(SourceSize.z, 0.0);
    oney = vec2(0.0, SourceSize.w);
}

#elif defined(FRAGMENT)

#if __VERSION__ >= 130
#define COMPAT_VARYING in
#define COMPAT_TEXTURE texture
out vec4 FragColor;
#else
#define COMPAT_VARYING varying
#define FragColor gl_FragColor
#define COMPAT_TEXTURE 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 COMPAT_PRECISION float opacity = 1.0;
uniform sampler2D Texture;
COMPAT_VARYING vec4 TEX0;
COMPAT_VARYING vec2 onex;
COMPAT_VARYING vec2 oney;

// Compatibility #defines
#define Source Texture
#define vTexCoord TEX0.xy

#define SourceSize vec4(TextureSize, 1.0 / TextureSize) // Either TextureSize or InputSize.
#define OutputSize vec4(OutputSize, 1.0 / OutputSize)

#ifdef PARAMETER_UNIFORM
// All parameter floats need to have COMPAT_PRECISION in front of them.
uniform COMPAT_PRECISION float SPOT_WIDTH;
uniform COMPAT_PRECISION float SPOT_HEIGHT;
uniform COMPAT_PRECISION float COLOR_BOOST;
uniform COMPAT_PRECISION float InputGamma;
uniform COMPAT_PRECISION float OutputGamma;
#else
#define SPOT_WIDTH 0.9
#define SPOT_HEIGHT 0.75
#define COLOR_BOOST 1.45
#define InputGamma 2.4
#define OutputGamma 2.2
#endif

#define GAMMA_IN(color) pow(color, vec4(InputGamma))
#define GAMMA_OUT(color) pow(color, vec4(1.0 / OutputGamma))

#define TEX2D(coords) GAMMA_IN(COMPAT_TEXTURE(Source, coords))

// Macro for weights computing.
#define WEIGHT(w)                                                                                  \
    if (w > 1.0)                                                                                   \
        w = 1.0;                                                                                   \
    w = 1.0 - w * w;                                                                               \
    w = w * w;

void main()
{
    vec2 coords = (vTexCoord * SourceSize.xy);
    vec2 pixel_center = floor(coords) + vec2(0.5, 0.5);
    vec2 texture_coords = pixel_center * SourceSize.zw;

    vec4 color = TEX2D(texture_coords);
    float dx = coords.x - pixel_center.x;

    float h_weight_00 = dx / SPOT_WIDTH;
    WEIGHT(h_weight_00);

    color *= vec4(h_weight_00, h_weight_00, h_weight_00, h_weight_00);

    // Get closest horizontal neighbour to blend.
    vec2 coords01;
    if (dx > 0.0) {
        coords01 = onex;
        dx = 1.0 - dx;
    }
    else {
        coords01 = -onex;
        dx = 1.0 + dx;
    }
    vec4 colorNB = TEX2D(texture_coords + coords01);

    float h_weight_01 = dx / SPOT_WIDTH;
    WEIGHT(h_weight_01);

    color = color + colorNB * vec4(h_weight_01);

    // Vertical blending.
    float dy = coords.y - pixel_center.y;
    float v_weight_00 = dy / SPOT_HEIGHT;
    WEIGHT(v_weight_00);
    color *= vec4(v_weight_00);

    // get closest vertical neighbour to blend
    vec2 coords10;
    if (dy > 0.0) {
        coords10 = oney;
        dy = 1.0 - dy;
    }
    else {
        coords10 = -oney;
        dy = 1.0 + dy;
    }
    colorNB = TEX2D(texture_coords + coords10);

    float v_weight_10 = dy / SPOT_HEIGHT;
    WEIGHT(v_weight_10);

    color = color + colorNB * vec4(v_weight_10 * h_weight_00, v_weight_10 * h_weight_00,
                                   v_weight_10 * h_weight_00, v_weight_10 * h_weight_00);
    colorNB = TEX2D(texture_coords + coords01 + coords10);
    color = color + colorNB * vec4(v_weight_10 * h_weight_01, v_weight_10 * h_weight_01,
                                   v_weight_10 * h_weight_01, v_weight_10 * h_weight_01);
    color *= vec4(COLOR_BOOST);

    vec4 colorTemp = clamp(GAMMA_OUT(color), 0.0, 1.0);
    FragColor = vec4(colorTemp.rgb, colorTemp.a * opacity);
}
#endif