slang-shaders/dithering/shaders/ps1dither/PS1-Undither-AntiBayer.slang

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#version 450
// PS1 Undither AntiBayer
// by torridgristle
layout(push_constant) uniform Push
{
vec4 SourceSize;
vec4 OriginalSize;
vec4 OutputSize;
uint FrameCount;
} params;
layout(std140, set = 0, binding = 0) uniform UBO
{
mat4 MVP;
} 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;
}
// PlayStation dithering pattern. The offset is selected based on the
// pixel position in VRAM, by blocks of 4x4 pixels. The value is added
// to the 8bit color components before they're truncated to 5 bits.
//"const int dither_pattern[16] ="
//" int[16](-4, 0, -3, 1,"
//" 2, -2, 3, -1,"
//" -3, 1, -4, 0,"
//" 3, -1, 2, -2);" "\n"
#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()
{
vec3 OriginPass = texture(Source, vTexCoord).xyz;
float PatternLUT[16] = float[](-4.0, 0.0, -3.0, 1.0,
2.0, -2.0, 3.0, -1.0,
-3.0, 1.0, -4.0, 0.0,
3.0, -1.0, 2.0, -2.0);
float PatternX = ceil(((mod(vTexCoord.x * params.SourceSize.x,4.00001)-0.5)/3.0)*3.0);
float PatternY = ceil(((mod(vTexCoord.y * params.SourceSize.y,4.00001)-0.5)/3.0)*3.0);
float Pattern = PatternLUT[int(PatternX+(PatternY*4))];
vec3 Result = OriginPass;
//Result = vec3(Pattern)/8.0 + 0.5;
Result = (Result * 255.0 - Pattern - round(Pattern*0.25)*2.0) / 255.0;
FragColor = vec4(Result,1.0);
}