// NTSC Shader - written by Hans-Kristian Arntzen
// License: GPLv3
// pulled from git://github.com/libretro/common-shaders.git on 01/30/2014

#version 150

uniform sampler2D source[];
uniform vec4 sourceSize[];
uniform vec4 targetSize;
uniform int phase;

// uniforms added for compatibility
out vec3 col;
out float mod_phase;
out float chroma_phase;

#define THREE_PHASE
#define COMPOSITE

// #include "ntsc-param.inc" //
#define PI 3.14159265

#if defined(TWO_PHASE)
#define CHROMA_MOD_FREQ (4.0 * PI / 15.0)
#elif defined(THREE_PHASE)
#define CHROMA_MOD_FREQ (PI / 3.0)
#endif

#if defined(COMPOSITE)
#define SATURATION 1.0
#define BRIGHTNESS 1.0
#define ARTIFACTING 1.0
#define FRINGING 1.0
#elif defined(SVIDEO)
#define SATURATION 1.0
#define BRIGHTNESS 1.0
#define ARTIFACTING 0.0
#define FRINGING 0.0
#endif

#if defined(COMPOSITE) || defined(SVIDEO)
mat3 mix_mat = mat3(
	BRIGHTNESS, FRINGING, FRINGING,
	ARTIFACTING, 2.0 * SATURATION, 0.0,
	ARTIFACTING, 0.0, 2.0 * SATURATION
);
#endif
// END "ntsc-param.inc" //

// moved from vertex
#define pix_no (texCoord.xy * sourceSize[0].xy * (targetSize.xy / sourceSize[0].xy))

in Vertex {
  vec2 texCoord;
};

out vec4 fragColor;

mat3 yiq2rgb_mat = mat3(
   1.0, 1.0, 1.0,
   0.956, -0.2720, -1.1060,
   0.6210, -0.6474, 1.7046
);

vec3 yiq2rgb(vec3 yiq)
{
   return (yiq * yiq2rgb_mat);
}

mat3 yiq_mat = mat3(
      0.2989, 0.5959, 0.2115,
      0.5870, -0.2744, -0.5229,
      0.1140, -0.3216, 0.3114
);

vec3 rgb2yiq(vec3 col)
{
   return (col * yiq_mat);
}

void main() {
// #include "ntsc-pass1-encode-demodulate.inc" //
vec3 col = texture(source[0], texCoord).rgb;
vec3 yiq = rgb2yiq(col);

#if defined(TWO_PHASE)
float chroma_phase = PI * (mod(pix_no.y, 2.0) + phase);
#elif defined(THREE_PHASE)
float chroma_phase = 0.6667 * PI * (mod(pix_no.y, 3.0) + phase);
#endif

float mod_phase = chroma_phase + pix_no.x * CHROMA_MOD_FREQ;

float i_mod = cos(mod_phase);
float q_mod = sin(mod_phase);

yiq.yz *= vec2(i_mod, q_mod); // Modulate
yiq = mul(mix_mat, yiq); // Cross-talk
yiq.yz *= vec2(i_mod, q_mod); // Demodulate

fragColor = vec4(yiq, 1.0);
// END "ntsc-pass1-encode-demodulate.inc" //
}