slang-shaders/crt/crt-lottes.slang
2016-07-12 19:44:26 -05:00

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#version 450
layout(std140, set = 0, binding = 0) uniform UBO
{
mat4 MVP;
vec4 OutputSize;
vec4 OriginalSize;
vec4 SourceSize;
} global;
#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;
}
// PUBLIC DOMAIN CRT STYLED SCAN-LINE SHADER
//
// by Timothy Lottes
//
// This is more along the style of a really good CGA arcade monitor.
// With RGB inputs instead of NTSC.
// The shadow mask example has the mask rotated 90 degrees for less chromatic aberration.
//
// Left it unoptimized to show the theory behind the algorithm.
//
// It is an example what I personally would want as a display option for pixel art games.
// Please take and use, change, or whatever.
#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
layout(location = 1) in vec2 FragCoord;
layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D Source;
// -- config -- //
#define hardScan -8.0
#define hardPix -3.0
#define warpX 0.031
#define warpY 0.041
#define maskDark 0.5
#define maskLight 1.5
#define scaleInLinearGamma 1
#define shadowMask 1
#define brightboost 1
#define hardBloomScan -2.0
#define hardBloomPix -1.5
#define bloomAmount 1.0/16.0
#define shape 2.0
//Uncomment to reduce instructions with simpler linearization
//(fixes HD3000 Sandy Bridge IGP)
//#define SIMPLE_LINEAR_GAMMA
#define DO_BLOOM 1
// ------------- //
// sRGB to Linear.
// Assuming using sRGB typed textures this should not be needed.
#ifdef SIMPLE_LINEAR_GAMMA
float ToLinear1(float c)
{
return c;
}
float3 ToLinear(vec3 c)
{
return c;
}
vec3 ToSrgb(vec3 c)
{
return pow(c, 1.0 / 2.2);
}
#else
float ToLinear1(float c)
{
if (scaleInLinearGamma==0) return c;
return(c<=0.04045)?c/12.92:pow((c+0.055)/1.055,2.4);
}
vec3 ToLinear(vec3 c)
{
if (scaleInLinearGamma==0) return c;
return vec3(ToLinear1(c.r),ToLinear1(c.g),ToLinear1(c.b));
}
// Linear to sRGB.
// Assuming using sRGB typed textures this should not be needed.
float ToSrgb1(float c)
{
if (scaleInLinearGamma==0) return c;
return(c<0.0031308?c*12.92:1.055*pow(c,0.41666)-0.055);
}
vec3 ToSrgb(vec3 c)
{
if (scaleInLinearGamma==0) return c;
return vec3(ToSrgb1(c.r),ToSrgb1(c.g),ToSrgb1(c.b));
}
#endif
// Nearest emulated sample given floating point position and texel offset.
// Also zero's off screen.
vec3 Fetch(vec2 pos,vec2 off){
pos=(floor(pos*global.SourceSize.xy+off)+vec2(0.5,0.5))/global.SourceSize.xy;
#ifdef SIMPLE_LINEAR_GAMMA
return ToLinear(brightboost * pow(texture(Source,pos.xy).rgb, 2.2));
#else
return ToLinear(brightboost * texture(Source,pos.xy).rgb);}
#endif
// Distance in emulated pixels to nearest texel.
vec2 Dist(vec2 pos){pos=pos*global.SourceSize.xy;return -((pos-floor(pos))-vec2(0.5));}
// 1D Gaussian.
float Gaus(float pos,float scale){return exp2(scale*pow(abs(pos),shape));}
// 3-tap Gaussian filter along horz line.
vec3 Horz3(vec2 pos,float off){
vec3 b=Fetch(pos,vec2(-1.0,off));
vec3 c=Fetch(pos,vec2( 0.0,off));
vec3 d=Fetch(pos,vec2( 1.0,off));
float dst=Dist(pos).x;
// Convert distance to weight.
float scale=hardPix;
float wb=Gaus(dst-1.0,scale);
float wc=Gaus(dst+0.0,scale);
float wd=Gaus(dst+1.0,scale);
// Return filtered sample.
return (b*wb+c*wc+d*wd)/(wb+wc+wd);}
// 5-tap Gaussian filter along horz line.
vec3 Horz5(vec2 pos,float off){
vec3 a=Fetch(pos,vec2(-2.0,off));
vec3 b=Fetch(pos,vec2(-1.0,off));
vec3 c=Fetch(pos,vec2( 0.0,off));
vec3 d=Fetch(pos,vec2( 1.0,off));
vec3 e=Fetch(pos,vec2( 2.0,off));
float dst=Dist(pos).x;
// Convert distance to weight.
float scale=hardPix;
float wa=Gaus(dst-2.0,scale);
float wb=Gaus(dst-1.0,scale);
float wc=Gaus(dst+0.0,scale);
float wd=Gaus(dst+1.0,scale);
float we=Gaus(dst+2.0,scale);
// Return filtered sample.
return (a*wa+b*wb+c*wc+d*wd+e*we)/(wa+wb+wc+wd+we);}
// 7-tap Gaussian filter along horz line.
vec3 Horz7(vec2 pos,float off){
vec3 a=Fetch(pos,vec2(-3.0,off));
vec3 b=Fetch(pos,vec2(-2.0,off));
vec3 c=Fetch(pos,vec2(-1.0,off));
vec3 d=Fetch(pos,vec2( 0.0,off));
vec3 e=Fetch(pos,vec2( 1.0,off));
vec3 f=Fetch(pos,vec2( 2.0,off));
vec3 g=Fetch(pos,vec2( 3.0,off));
float dst=Dist(pos).x;
// Convert distance to weight.
float scale=hardBloomPix;
float wa=Gaus(dst-3.0,scale);
float wb=Gaus(dst-2.0,scale);
float wc=Gaus(dst-1.0,scale);
float wd=Gaus(dst+0.0,scale);
float we=Gaus(dst+1.0,scale);
float wf=Gaus(dst+2.0,scale);
float wg=Gaus(dst+3.0,scale);
// Return filtered sample.
return (a*wa+b*wb+c*wc+d*wd+e*we+f*wf+g*wg)/(wa+wb+wc+wd+we+wf+wg);}
// Return scanline weight.
float Scan(vec2 pos,float off){
float dst=Dist(pos).y;
return Gaus(dst+off,hardScan);}
// Return scanline weight for bloom.
float BloomScan(vec2 pos,float off){
float dst=Dist(pos).y;
return Gaus(dst+off,hardBloomScan);}
// Allow nearest three lines to effect pixel.
vec3 Tri(vec2 pos){
vec3 a=Horz3(pos,-1.0);
vec3 b=Horz5(pos, 0.0);
vec3 c=Horz3(pos, 1.0);
float wa=Scan(pos,-1.0);
float wb=Scan(pos, 0.0);
float wc=Scan(pos, 1.0);
return a*wa+b*wb+c*wc;}
// Small bloom.
vec3 Bloom(vec2 pos){
vec3 a=Horz5(pos,-2.0);
vec3 b=Horz7(pos,-1.0);
vec3 c=Horz7(pos, 0.0);
vec3 d=Horz7(pos, 1.0);
vec3 e=Horz5(pos, 2.0);
float wa=BloomScan(pos,-2.0);
float wb=BloomScan(pos,-1.0);
float wc=BloomScan(pos, 0.0);
float wd=BloomScan(pos, 1.0);
float we=BloomScan(pos, 2.0);
return a*wa+b*wb+c*wc+d*wd+e*we;}
// Distortion of scanlines, and end of screen alpha.
vec2 Warp(vec2 pos){
pos=pos*2.0-1.0;
pos*=vec2(1.0+(pos.y*pos.y)*warpX,1.0+(pos.x*pos.x)*warpY);
return pos*0.5+0.5;}
// Shadow mask.
vec3 Mask(vec2 pos){
vec3 mask=vec3(maskDark,maskDark,maskDark);
// Very compressed TV style shadow mask.
if (shadowMask == 1.0) {
float line=maskLight;
float odd=0.0;
if(fract(pos.x/6.0)<0.5)odd=1.0;
if(fract((pos.y+odd)/2.0)<0.5)line=maskDark;
pos.x=fract(pos.x/3.0);
if(pos.x<0.333)mask.r=maskLight;
else if(pos.x<0.666)mask.g=maskLight;
else mask.b=maskLight;
mask*=line;
}
// Aperture-grille.
else if (shadowMask == 2.0) {
pos.x=fract(pos.x/3.0);
if(pos.x<0.333)mask.r=maskLight;
else if(pos.x<0.666)mask.g=maskLight;
else mask.b=maskLight;
}
// Stretched VGA style shadow mask (same as prior shaders).
else if (shadowMask == 3.0) {
pos.x+=pos.y*3.0;
pos.x=fract(pos.x/6.0);
if(pos.x<0.333)mask.r=maskLight;
else if(pos.x<0.666)mask.g=maskLight;
else mask.b=maskLight;
}
// VGA style shadow mask.
else if (shadowMask == 4.0) {
pos.xy=floor(pos.xy*vec2(1.0,0.5));
pos.x+=pos.y*3.0;
pos.x=fract(pos.x/6.0);
if(pos.x<0.333)mask.r=maskLight;
else if(pos.x<0.666)mask.g=maskLight;
else mask.b=maskLight;
}
return mask;}
void main()
{
vec2 pos=Warp(vTexCoord);
vec3 outColor = Tri(pos);
#ifdef DO_BLOOM
//Add Bloom
outColor.rgb+=Bloom(pos)*bloomAmount;
#endif
if(shadowMask > 0.0)
outColor.rgb*=Mask(vTexCoord.xy / global.OutputSize.zw * 1.000001);
FragColor = vec4(ToSrgb(outColor.rgb), 1.0);
}