crt.hlsl

// Data provided by Windows Terminal
Texture2D shaderTexture;
SamplerState samplerState;

cbuffer PixelShaderSettings {
	float  Time;
	float  Scale;
	float2 Resolution;
	float4 Background;
};

// Settings
#define GRAIN_INTENSITY 0.02
#define TINT_COLOR float4(1, 0.7f, 0, 0)
#define ENABLE_SCANLINES 1
#define ENABLE_REFRESHLINE 1
#define ENABLE_NOISE 1
#define ENABLE_CURVE 1
#define ENABLE_TINT 0
#define DEBUG 0

// Grain Lookup Table
#define a0  0.151015505647689
#define a1 -0.5303572634357367
#define a2  1.365020122861334
#define b0  0.132089632343748
#define b1 -0.7607324991323768

static const float4 tint = TINT_COLOR;
static const float4 scanlineTint = float4(0.6f, 0.6f, 0.6f, 0.0f);

float permute(float x)
{
	x *= (34 * x + 1);
	return 289 * frac(x * 1 / 289.0f);
}

float rand(inout float state)
{
	state = permute(state);
	return frac(state / 41.0f);
}

float4 mainImage(float2 tex) : TARGET
{
	float2 xy = tex.xy;
	
	#if ENABLE_CURVE
	// TODO: add control variable for transform intensity
	xy -= 0.5f;				// offcenter screen
	float r = xy.x * xy.x + xy.y * xy.y; 	// get ratio
	xy *= 4.2f + r;				// apply ratio
	xy *= 0.25f;				// zoom
	xy += 0.5f;				// move back to center

	// TODO: add monitor visuals and make colors static consts
	// Outter Box
	if(xy.x < -0.025f || xy.y < -0.025f) return float4(0, 0, 0, 0); 
	if(xy.x > 1.025f  || xy.y > 1.025f)  return float4(0, 0, 0, 0); 
	// Bazel
	if(xy.x < -0.015f || xy.y < -0.015f) return float4(0.03f, 0.03f, 0.03f, 0.0f);
	if(xy.x > 1.015f  || xy.y > 1.015f)  return float4(0.03f, 0.03f, 0.03f, 0.0f);
	// Screen Border
	if(xy.x < 0.001f  || xy.y < 0.001f)  return float4(0.0f, 0.0f, 0.0f, 0.0f);
	if(xy.x > 0.999f  || xy.y > 0.999f)  return float4(0.0f, 0.0f, 0.0f, 0.0f);
	#endif
	
	float4 color = shaderTexture.Sample(samplerState, xy);

	#if DEBUG
	if(xy.x < 0.5f) return color;
	#endif

	#if ENABLE_REFRESHLINE
	float timeOver = fmod(Time / 5, 1);
	float refreshLineColorTint = timeOver - xy.y;
	if(xy.y > timeOver && xy.y - 0.03f < timeOver ) color.rgb += (refreshLineColorTint * 2.0f);
	#endif

	#if ENABLE_SCANLINES
	// TODO: fixing the precision issue so that scanlines are always 1px
	if(floor(xy.y * 1000) % 2) color *= scanlineTint;
	#endif	

	#if ENABLE_TINT
	float grayscale = (color.r + color.g + color.b) / 3.f;
	color = float4(grayscale, grayscale, grayscale, 0);
	color *= tint;
	#endif

	#if ENABLE_GRAIN
	float3 m = float3(tex, Time % 5 / 5) + 1.;
	float state = permute(permute(m.x) + m.y) + m.z;

	float p = 0.95 * rand(state) + 0.025;
	float q = p - 0.5;
	float r2 = q * q;

	float grain = q * (a2 + (a1 * r2 + a0) / (r2 * r2 + b1 * r2 + b0));
	color.rgb += GRAIN_INTENSITY * grain;
	#endif

	return color;
}

float4 main(float4 pos : SV_POSITION, float2 tex : TEXCOORD) : SV_TARGET
{
	return mainImage(tex);
}