#version 440

#ifndef CRT_RASTER_MODE
#define CRT_RASTER_MODE 0
#endif
#ifndef CRT_BURN_IN
#define CRT_BURN_IN 1
#endif
#ifndef CRT_DISPLAY_FRAME
#define CRT_DISPLAY_FRAME 1
#endif
#ifndef CRT_CHROMA
#define CRT_CHROMA 1
#endif

layout(location = 0) in vec2 qt_TexCoord0;
layout(location = 1) in float vBrightness;
layout(location = 2) in float vDistortionScale;
layout(location = 3) in float vDistortionFreq;

layout(location = 0) out vec4 fragColor;

layout(std140, binding = 0) uniform ubuf {
    mat4 qt_Matrix;
    float qt_Opacity;
    float time;
    vec4 fontColor;
    vec4 backgroundColor;
    vec2 virtualResolution;
    float rasterizationIntensity;
    float burnInLastUpdate;
    float burnInTime;
    float burnIn;
    float staticNoise;
    float screenCurvature;
    float glowingLine;
    float chromaColor;
    vec2 jitterDisplacement;
    float jitter;
    float horizontalSync;
    float horizontalSyncStrength;
    float flickering;
    float displayTerminalFrame;
    vec2 scaleNoiseSize;
    float frameShininess;
    float frameSize;
    float bloom;
};

layout(binding = 0) uniform sampler2D noiseSource;
layout(binding = 1) uniform sampler2D screenBuffer;
layout(binding = 2) uniform sampler2D burnInSource;
layout(binding = 3) uniform sampler2D frameSource;

float min2(vec2 v) { return min(v.x, v.y); }
float prod2(vec2 v) { return v.x * v.y; }
float sum2(vec2 v) { return v.x + v.y; }
float rgb2grey(vec3 v) { return dot(v, vec3(0.21, 0.72, 0.04)); }

vec2 distortCoordinates(vec2 coords){
    vec2 paddedCoords = coords * (vec2(1.0) + frameSize * 2.0) - frameSize;
    vec2 cc = (paddedCoords - vec2(0.5));
    float dist = dot(cc, cc) * screenCurvature;
    return (paddedCoords + cc * (1.0 + dist) * dist);
}

vec3 applyRasterization(vec2 screenCoords, vec3 texel, vec2 virtualRes, float intensity) {
#if CRT_RASTER_MODE == 0 || CRT_RASTER_MODE == 4
    return texel;
#else
    if (intensity <= 0.0) {
        return texel;
    }

    const float INTENSITY = 0.30;
    const float BRIGHTBOOST = 0.30;

#if CRT_RASTER_MODE == 1
    vec3 pixelHigh = ((1.0 + BRIGHTBOOST) - (0.2 * texel)) * texel;
    vec3 pixelLow  = ((1.0 - INTENSITY) + (0.1 * texel)) * texel;

    vec2 coords = fract(screenCoords * virtualRes) * 2.0 - vec2(1.0);
    float mask = 1.0 - abs(coords.y);

    vec3 rasterizationColor = mix(pixelLow, pixelHigh, mask);
    return mix(texel, rasterizationColor, intensity);
#elif CRT_RASTER_MODE == 2
    vec3 pixelHigh = ((1.0 + BRIGHTBOOST) - (0.2 * texel)) * texel;
    vec3 pixelLow  = ((1.0 - INTENSITY) + (0.1 * texel)) * texel;

    vec2 coords = fract(screenCoords * virtualRes) * 2.0 - vec2(1.0);
    coords = coords * coords;
    float mask = 1.0 - coords.x - coords.y;

    vec3 rasterizationColor = mix(pixelLow, pixelHigh, mask);
    return mix(texel, rasterizationColor, intensity);
#elif CRT_RASTER_MODE == 3
    const float SUBPIXELS = 3.0;
    vec3 offsets = vec3(3.141592654) * vec3(0.5, 0.5 - 2.0 / 3.0, 0.5 - 4.0 / 3.0);

    vec2 omega = vec2(3.141592654) * vec2(2.0) * virtualRes;
    vec2 angle = screenCoords * omega;
    vec3 xfactors = (SUBPIXELS + sin(angle.x + offsets)) / (SUBPIXELS + 1.0);

    vec3 result = texel * xfactors;
    vec3 pixelHigh = ((1.0 + BRIGHTBOOST) - (0.2 * result)) * result;
    vec3 pixelLow  = ((1.0 - INTENSITY) + (0.1 * result)) * result;

    vec2 coords = fract(screenCoords * virtualRes) * 2.0 - vec2(1.0);
    float mask = 1.0 - abs(coords.y);

    vec3 rasterizationColor = mix(pixelLow, pixelHigh, mask);
    return mix(texel, rasterizationColor, intensity);
#else
    return texel;
#endif
#endif
}

float randomPass(vec2 coords){
    return fract(smoothstep(-120.0, 0.0, coords.y - (virtualResolution.y + 120.0) * fract(time * 0.15)));
}

vec3 convertWithChroma(vec3 inColor) {
#if CRT_CHROMA == 1
    float grey = rgb2grey(inColor);
    float denom = max(grey, 0.0001);
    vec3 foregroundColor = mix(fontColor.rgb, inColor * fontColor.rgb / denom, chromaColor);
    return mix(backgroundColor.rgb, foregroundColor, grey);
#else
    return mix(backgroundColor.rgb, fontColor.rgb, rgb2grey(inColor));
#endif
}

void main() {
    vec2 cc = vec2(0.5) - qt_TexCoord0;
    float distance = length(cc);

    vec2 staticCoords = distortCoordinates(qt_TexCoord0);
    vec2 coords = qt_TexCoord0;

    float dst = sin((coords.y + time) * vDistortionFreq);
    coords.x += dst * vDistortionScale;

    vec4 noiseTexel = texture(noiseSource, scaleNoiseSize * coords + vec2(fract(time / 0.051), fract(time / 0.237)));

    vec2 txt_coords = coords + (noiseTexel.ba - vec2(0.5)) * jitterDisplacement * jitter;

    float color = 0.0001;
    color += noiseTexel.a * staticNoise * (1.0 - distance * 1.3);
    color += randomPass(coords * virtualResolution) * glowingLine;

#if CRT_DISPLAY_FRAME == 1
    vec4 frameColor = texture(frameSource, qt_TexCoord0);
    color *= (1.0 - frameColor.a);
#endif

    vec3 txt_color = texture(screenBuffer, txt_coords).rgb;
    float bloomScale = 1.0 + max(bloom, 0.0);
    txt_color *= bloomScale;

#if CRT_BURN_IN == 1
    vec4 txt_blur = texture(burnInSource, staticCoords);
    float blurDecay = clamp((time - burnInLastUpdate) * burnInTime, 0.0, 1.0);
    vec3 burnInColor = 0.65 * (txt_blur.rgb - vec3(blurDecay)) * (1.0 - txt_blur.a);
    txt_color = max(txt_color, burnInColor);
#endif

    txt_color += vec3(color);
    txt_color = applyRasterization(staticCoords, txt_color, virtualResolution, rasterizationIntensity);

    vec3 finalColor = convertWithChroma(txt_color);
    float brightness = mix(1.0, vBrightness, step(0.0, flickering));
    finalColor *= brightness;

#if CRT_DISPLAY_FRAME == 1
    finalColor = mix(finalColor, frameColor.rgb, frameColor.a);
#endif

    fragColor = vec4(finalColor, qt_Opacity);
}