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Add gizmo-slotmask-crt

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This shader tries to reproduce a CRT-like output without replicating a RGB patterns.

It has the following features:
- allows fractional scaling
- uses texture AA shader and subpixel scaling for evenly placed sharp pixels
- has a horizontal blur function which mimics bad signal quality of some systems (megadrive, psx)
- has a vertical blur function which mimics n64 vertical software blur
- adds some noise to mimic restless CRT colors
- has a curvator function
- looks good with resolutions <= 1080p
- has modest system requirements
- adds a slotmask to the output.

https://forums.libretro.com/t/gizmo-slotmask-crt-shader/41594
This commit is contained in:
gizmo98 2023-05-13 22:13:05 +02:00
parent a6305a1789
commit 7783ff6ad6
2 changed files with 286 additions and 0 deletions
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crt/gizmo-slotmask-crt.slangp Normal file
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shaders = "1"
shader0 = "shaders/gizmo-slotmask-crt.slang"
filter_linear0 = "true"
wrap_mode0 = "clamp_to_border"
mipmap_input0 = "false"
alias0 = ""
float_framebuffer0 = "false"
srgb_framebuffer0 = "false"
parameters = "BRIGHTNESS;HORIZONTAL_BLUR;VERTICAL_BLUR;BLUR_OFFSET;BGR_LCD_PATTERN;SHRINK;SNR;COLOUR_BLEEDING;GRID;SLOTMASK"
CURVATURE_X = "0.15"
CURVATURE_Y = "0.15"
BRIGHTNESS = "0.5"
HORIZONTAL_BLUR = "1.0"
VERTICAL_BLUR = "0.0"
BLUR_OFFSET = "0.65"
BGR_LCD_PATTERN = "0.0"
SHRINK = "0.0"
SNR = "2.6"
COLOUR_BLEEDING = "0.15"
GRID = "0.30"
SLOTMASK = "1.0"

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crt/shaders/gizmo-slotmask-crt.slang Normal file
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#version 450
/*
* gizmo98 slotmask crt shader
* Copyright (C) 2023 gizmo98
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* version 0.1, 10.05.2023
* ---------------------------------------------------------------------------------------
* - initial commit
*
* https://github.com/gizmo98/gizmo-crt-shader
*
* This shader tries to mimic a CRT without extensive use of scanlines and masks and rgb pattern emulation.
* It uses horizontal subpixel scaling and adds brightness dependent scanline patterns and allows
* fractional scaling.
*
* HORIZONTAL_BLUR simulates a bad composite signal which is neede for consoles like megadrive
* VERTICAL_BLUR vertical blur simulates N64 vertical blur
* BGR_LCD_PATTERN most LCDs have a RGB pixel pattern. Enable BGR pattern with this switch
* BRIGHTNESS makes scanlines more or less visible
* SHRINK scale screen in X direction
* SNR noise intensity
* COLOUR_BLEEDING colour bleeding intensity
* GRID slotmask intensity
* SLOTMASK switch between slotmask (1) and aperture grille (0)
*
* uses parts curvator of CRT-PI shader from davej https://github.com/libretro/glsl-shaders/blob/master/crt/shaders/crt-pi.glsl
* uses parts of texture anti-aliasing shader from Ikaros https://www.shadertoy.com/view/ldsSRX
* uses gold noise shader from dcerisano https://www.shadertoy.com/view/ltB3zD
*/
layout(push_constant) uniform Push
{
vec4 SourceSize;
vec4 OriginalSize;
vec4 OutputSize;
uint FrameCount;
float CURVATURE_X;
float CURVATURE_Y;
float BRIGHTNESS;
float HORIZONTAL_BLUR;
float VERTICAL_BLUR;
float BLUR_OFFSET;
float BGR_LCD_PATTERN;
float SHRINK;
float SNR;
float COLOUR_BLEEDING;
float GRID;
float SLOTMASK;
} params;
layout(std140, set = 0, binding = 0) uniform UBO
{
mat4 MVP;
} global;
#pragma parameter CURVATURE_X "Screen curvature - horizontal" 0.10 0.0 1.0 0.01
#pragma parameter CURVATURE_Y "Screen curvature - vertical" 0.15 0.0 1.0 0.01
#pragma parameter BRIGHTNESS "Scanline Intensity" 0.5 0.05 1.0 0.05
#pragma parameter HORIZONTAL_BLUR "Horizontal Blur" 0.0 0.0 1.0 1.0
#pragma parameter VERTICAL_BLUR "Vertical Blur" 0.0 0.0 1.0 1.0
#pragma parameter BLUR_OFFSET "Blur Intensity" 0.5 0.0 1.0 0.05
#pragma parameter BGR_LCD_PATTERN "BGR output pattern" 0.0 0.0 1.0 1.0
#pragma parameter SHRINK "Horizontal scale" 0.0 0.0 1.0 0.01
#pragma parameter SNR "Noise intensity" 1.0 0.0 2.0 0.1
#pragma parameter COLOUR_BLEEDING "Colour bleeding intensity" 0.0 0.0 3.0 0.1
#pragma parameter GRID "Grid intensity" 0.0 0.0 3.0 0.05
#pragma parameter SLOTMASK "Use slot mask" 0.0 0.0 1.0 1.0
#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;
float PHI = 1.61803398874989484820459; // Φ = Golden Ratio
float gold_noise(in vec2 xy, in float seed){
return fract(tan(distance(xy*PHI, xy)*seed)*xy.x);
}
vec2 saturateA(in vec2 x)
{
return clamp(x, 0.0, 1.0);
}
vec2 magnify(in vec2 uv, in vec2 res)
{
uv *= res;
return (saturateA(fract(uv) / saturateA(fwidth(uv))) + floor(uv) - 0.5) / res.xy;
}
vec4 textureAABlur(in vec2 uv){
vec2 texSize = vec2(textureSize(Source, 0));
uv = magnify(uv,texSize.xy);
uv = uv*texSize.xy + 0.5;
vec2 iuv = floor(uv);
vec2 fuv = uv - iuv;
if (params.HORIZONTAL_BLUR == 1.0){
vec2 uv1 = vec2(uv + vec2(-0.5,-0.5)) / texSize.xy;
vec2 uv2 = vec2(uv + vec2(-0.5 - params.BLUR_OFFSET,-0.5)) / texSize.xy;
vec4 col1 = texture( Source, uv1 );
vec4 col2 = texture( Source, uv2 );
vec4 col = (col1 + col2) / vec4(2.0);
if (params.VERTICAL_BLUR == 1.0){
vec2 uv3 = vec2(uv + vec2(-0.5,-0.5 - params.BLUR_OFFSET)) / texSize.xy;
vec2 uv4 = vec2(uv + vec2(-0.5 - params.BLUR_OFFSET,-0.5 - params.BLUR_OFFSET)) / texSize.xy;
vec4 col3 = texture( Source, uv3 );
vec4 col4 = texture( Source, uv4 );
col = (((col3 + col4) / vec4(2.0)) + col) / vec4(2.0);
}
return col;
}
else{
uv = vec2(uv + vec2(-0.5,-0.5)) / texSize.xy;
return texture( Source, uv );
}
}
vec4 textureSubpixelScaling(in vec2 uvr, in vec2 uvg, in vec2 uvb ){
return vec4(textureAABlur(uvr).r, textureAABlur(uvg).g, textureAABlur(uvb).b, 1.0);
}
float GetFuv(in vec2 uv){
vec2 texSize = vec2(textureSize(Source, 0));
uv = uv*texSize.xy + 0.5;
vec2 iuv = floor(uv);
vec2 fuv = uv - iuv;
return abs((fuv*fuv*fuv*(fuv*(fuv*6.0-15.0)+10.0)).y - 0.5);
}
vec4 AddNoise(in vec4 col, in vec2 coord){
/* Add some subpixel noise which simulates small CRT color variations */
float iGlobalTime = float(params.FrameCount)*0.025;
float snr = params.SNR * 0.03125;
return clamp(col + gold_noise(coord,sin(iGlobalTime)) * snr - snr/2.0,0.0,1.0);
}
vec4 AddScanlines(in vec4 col, in vec2 uvr, in vec2 uvg, in vec2 uvb){
/* Add scanlines which are wider for dark colors.
You cannot see scanlines if color is bright. */
vec2 texSize = vec2(textureSize(Source, 0));
float brightness = 1.0 / params.BRIGHTNESS * 0.05;
float scale = (params.OutputSize.y / texSize.y) * 0.5;
float dim = brightness * scale;
col.rgb -= dim * (abs(1.5* (1.0 - col.rgb) * (0.5 - vec3(GetFuv(uvr), GetFuv(uvg), GetFuv(uvb)))));
return col;
}
vec4 AddGrid(in vec4 col, in vec2 coord){
vec2 texSize = vec2(textureSize(Source, 0));
float scale = (params.OutputSize.x / texSize.y) * 0.25;
if (mod(floor((coord.x) * 1.0) ,3.0) == 0.0){
col = mix(col,vec4(0.0,0.0,0.0,0.5 * scale),params.GRID);
}
else{
if (params.SLOTMASK == 1.0){
float field = fract (coord.x / 6.0);
if(((field >= 0.166 && field <= 0.5) && (mod(floor(coord.y * 1.0 + 1.0),3.0) == 0.0)) ||
((field >= 0.666 && field <= 1.0) && (mod(floor(coord.y * 1.0),3.0) == 0.0)))
col = mix(col,vec4(0.0,0.0,0.0,0.5 * scale),params.GRID*0.3);
}
}
return col;
}
vec3 XCoords(in float coord, in float factor){
float iGlobalTime = float(params.FrameCount)*0.025;
float spread = 1.0 / 3.0 + params.COLOUR_BLEEDING;;
vec3 coords = vec3(coord);
if(params.BGR_LCD_PATTERN == 1.0)
coords.r += spread * 2.0;
else
coords.b += spread * 2.0;
coords.g += spread;
coords *= factor;
return coords;
}
float YCoord(in float coord, in float factor){
return coord * factor;
}
vec2 CURVATURE_DISTORTION = vec2(params.CURVATURE_X, params.CURVATURE_Y);
// Barrel distortion shrinks the display area a bit, this will allow us to counteract that.
vec2 barrelScale = 1.0 - (0.23 * CURVATURE_DISTORTION);
vec2 Distort(vec2 coord)
{
// coord *= screenScale; // not necessary in slang
coord -= vec2(0.5);
float rsq = coord.x * coord.x + coord.y * coord.y;
coord += coord * (CURVATURE_DISTORTION * rsq);
coord *= barrelScale;
if (abs(coord.x) >= 0.5 || abs(coord.y) >= 0.5)
coord = vec2(-1.0); // If out of bounds, return an invalid value.
else
{
coord += vec2(0.5);
// coord /= screenScale; // not necessary in slang
}
return coord;
}
vec2 Jitter(vec2 coord)
{
float iGlobalTime = float(params.FrameCount)*0.025;
coord.y += sin(iGlobalTime * 220.1) * 0.10;
return coord;
}
void main()
{
vec2 texSize = vec2(textureSize(Source, 0));
vec2 texcoord = vTexCoord.xy;
if (params.SHRINK > 0.0)
{
texcoord.x -= 0.5;
texcoord.x *= 1.0 + params.SHRINK;
texcoord.x += 0.5;
}
texcoord = Distort(texcoord);
if (texcoord.x < 0.0)
{
FragColor = vec4(0.0);
return;
}
vec2 fragCoord = texcoord.xy * params.OutputSize.xy;
vec2 factor = texSize.xy / params.OutputSize.xy ;
fragCoord = Jitter(fragCoord);
highp float yCoord = YCoord(fragCoord.y, factor.y) ;
highp vec3 xCoords = XCoords(fragCoord.x, factor.x) ;
vec2 coord_r = vec2(xCoords.r/ texSize.x, texcoord.y) ;
vec2 coord_g = vec2(xCoords.g, yCoord) / texSize.xy;
vec2 coord_b = vec2(xCoords.b, yCoord) / texSize.xy;
FragColor = textureSubpixelScaling(coord_r,coord_g,coord_b);
FragColor = AddNoise(FragColor, fragCoord);
FragColor = AddScanlines(FragColor, coord_r, coord_g, coord_b);
FragColor = AddGrid(FragColor, gl_FragCoord.xy);
FragColor.a = 1.0;
}