slang-shaders/test/nonfunctional/shaders/gtu-famicom/lowPass.slang

#version 450

layout(push_constant) uniform Push
{
	vec4 OutputSize;
	vec4 OriginalSize;
	vec4 SourceSize;
	float signalResolution;
	float addNoise;
	float noiseStrength;
	uint FrameCount;
} params;

#pragma parameter signalResolution "Signal Resolution" 700.0 20.0 2000.0 10.0
#pragma parameter addNoise "Add Noise" 0.0 0.0 1.0 1.0
#pragma parameter noiseStrength "Noise Strength" 0.0 0.0 1.0 0.05

//#include "config.h"

layout(std140, set = 0, binding = 0) uniform UBO
{
   mat4 MVP;
} global;

////////////////////////////////////////////////////////
//	GTU-famicom version 0.50
//	Author: aliaspider - aliaspider@gmail.com
//	License: GPLv3      
////////////////////////////////////////////////////////

#define pi			3.14159265358
#define a(x) abs(x)
#define d(x,b) (pi*b*min(a(x)+0.5,1.0/b))
#define e(x,b) (pi*b*min(max(a(x)-0.5,-1.0/b),1.0/b))
#define STU(x,b) ((d(x,b)+sin(d(x,b))-e(x,b)-sin(e(x,b)))/(2.0*pi))
#define X(i) (offset-(i))
#define S(i) (texture(Source, vec2(vTexCoord.x - X(i)/params.SourceSize.x,vTexCoord.y)).x)
#define VAL(i) (S(i)*STU(X(i),(params.signalResolution * params.SourceSize.z)))

float rand(vec2 co)
{
    float c = 43758.5453;
    float dt= dot(co.xy ,vec2(12.9898,78.233));
    float sn= mod(dt,3.14);
    return fract(sin(sn) * c);
}


#pragma stage vertex
layout(location = 0) in vec4 Position;
layout(location = 1) in vec2 TexCoord;
layout(location = 0) out vec2 vTexCoord;

void main()
{
   gl_Position = global.MVP * Position;
   vTexCoord = TexCoord;
}

#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D Source;

void main()
{
	float	offset	=	fract((vTexCoord.x * params.SourceSize.x) - 0.50001);
	float	signal	=	0.0;
	float	range	=	ceil(0.50001 + params.SourceSize.x / params.signalResolution);
			range	=	min(range, 255.0);
			
	float i;
   for (i = 1-range; i < 1+range; i++)
      signal+=VAL(i);

   if(params.addNoise > 0.0)
   {
      vec2 pos = (vTexCoord.xy * params.SourceSize.xy);
	  signal -= 0.5;
      signal += (rand(vec2(pos.x * pos.y, params.FrameCount)) - 0.50001) * params.noiseStrength;
	  signal += 0.5;
   }
   FragColor = vec4(signal);
}