#if defined(VERTEX)

#pragma parameter ntsc_U "U Hue (Purple to Yellow)" 0.8 -6.0 6.0 0.05
#pragma parameter ntsc_V "V Hue (Red to Cyan)" 1.0 -6.0 6.0 0.05

#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;

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;
    TEX0.xy = TexCoord.xy*1.0001;
}

#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 sampler2D Texture;
COMPAT_VARYING vec4 TEX0;

#define vTexCoord TEX0.xy
#define Source Texture
#define SourceSize vec4(TextureSize,1.0/TextureSize)

#ifdef PARAMETER_UNIFORM
uniform COMPAT_PRECISION float ntsc_U;
uniform COMPAT_PRECISION float ntsc_V;
uniform COMPAT_PRECISION float system_choose;
uniform COMPAT_PRECISION float anim_overr;

#else
#define ntsc_U 0.6667
#define ntsc_V 0.6667
#define system_choose 0.0
#define anim_overr 0.0
#endif

#define pi 3.1415926
#define NTSC_CLOCK 3.579545
#define PAL_CLOCK 4.43361

mat3 rgb2yuv = mat3(0.299, 0.587, 0.114,
                        -0.299, -0.587, 0.886, 
                         0.701, -0.587, -0.114);
mat3 yuv2rgb = mat3(1.0, 0.0, 1.13983,
                          1.0, -0.39465, -0.58060,
                          1.0, 2.03211, 0.0);
void main()
{
    // nes & snes master clock, ppu needs 4 cycles per pixel, pce too on 256px. 320px pce is 21.47/3.0
    // ms too is the same clock
    float system_clock = 21.47727273/4.0; 
    // md uses 15*ntsc clock and each pixel has 8 cycles
    if (system_choose == 1.0) system_clock = NTSC_CLOCK/(15.0*NTSC_CLOCK/8.0);
    if (system_choose == 4.0) system_clock = PAL_CLOCK/7.0/2.0;
    // c64 runs 4*PAL/NTSC then divides 18 or 14(ntsc), feeds the cpu freq, then runs 8x times of cpu
    if (system_choose == 5.0) system_clock = PAL_CLOCK/(PAL_CLOCK*4.0/18.0*8.0);
    // Atari 2600 is 1:1 ntsc
    if (system_choose == 6.0) system_clock = 3.579545*2.0; // stella outputs double pixels? 

    float phase_alt = NTSC_CLOCK/system_clock;

    float v_phase_alt = phase_alt;
    float timer = mod(float(FrameCount+1),2.0);
    float hue_u = 0.0; 
    float hue_v = 0.0;
    // md doesn't alternate every line, doesn't animate too
    if (system_choose == 1.0) {v_phase_alt =0.0; timer = 0.0; hue_u = -3.0; hue_v = -3.0;}
    // pce alternates every two lines
    if (system_choose == 2.0) {v_phase_alt = 1.0; timer = 0.0;}
    if (system_choose == 3.0) {hue_u = 1.0; hue_v = 0.8; v_phase_alt = 0.0; timer = 0.0;}
    float altv = 0.0;
    if (system_choose == 4.0) {v_phase_alt = 0.0; timer = 0.0;hue_u = 1.8; 
        hue_v = 1.8; altv = mod(floor(vTexCoord.y * SourceSize.y + 0.5), 2.0) * pi;}
    if (system_choose == 5.0) {v_phase_alt = 0.0; timer = 0.0;hue_u = -3.2; 
        hue_v = -3.0; altv = mod(floor(vTexCoord.y * SourceSize.y + 0.5), 2.0) * pi;}
    if (system_choose == 6.0) {hue_u = -1.4;hue_v = -1.3;v_phase_alt = 1.0; timer = 0.0;}
    
    if (anim_overr == 1.0) timer = mod(float(FrameCount+1),2.0);    
    vec3 res = COMPAT_TEXTURE(Source, vTexCoord).rgb*rgb2yuv;

    float phase =  vTexCoord.x*SourceSize.x*pi*phase_alt- vTexCoord.y*SourceSize.y*pi*v_phase_alt + timer*pi*phase_alt +altv ;
    vec3 carrier = vec3(1.0,0.5*cos(phase-ntsc_U+hue_u),0.5*sin(phase-ntsc_V+hue_v));
    float signal = dot(vec3(1.0),res*carrier); 
    FragColor.rgb = vec3(signal);
} 
#endif
