slang-shaders/crt/shaders/dotmask.slang

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#version 450
layout(std140, set = 0, binding = 0) uniform UBO
{
mat4 MVP;
vec4 OutputSize;
vec4 OriginalSize;
vec4 SourceSize;
} global;
#define DOTMASK_STRENGTH 0.3
#define maskDark 0.5
#define maskLight 1.5
#define shadowMask 0.0
#define mod_factor vTexCoord.x * global.SourceSize.x * global.OutputSize.x / global.SourceSize.x
#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;
// 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()
{
vec3 res = texture(Source, vTexCoord).rgb;
float mask = 1.0 - DOTMASK_STRENGTH;
//cgwg's dotmask emulation:
//Output pixels are alternately tinted green and magenta
vec3 dotMaskWeights = mix(vec3(1.0, mask, 1.0),
vec3(mask, 1.0, mask),
floor(mod(mod_factor, 2.0)));
if (shadowMask == 0) {
res *= dotMaskWeights;
}
else {
res *= Mask(floor(1.000001 * vTexCoord.xy * global.OutputSize.xy + vec2(0.5)));
}
FragColor = vec4(res, 1.0);
}