slang-shaders/crt/shaders/crt-lottes-multipass/horz3minus1.slang
2016-07-26 10:27:29 -05:00

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#version 450
#define hardPix -3.0
#define brightboost 1
#define shape 2.0
layout(std140, set = 0, binding = 0) uniform UBO
{
mat4 MVP;
vec4 OutputSize;
vec4 OriginalSize;
vec4 REFERENCESize;
} 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;
// vTexCoord = floor(global.REFERENCESize.xy * TexCoord);
// vTexCoord = (vTexCoord + 0.5) * global.REFERENCESize.zw;
}
#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D REFERENCE;
// Nearest emulated sample given floating point position and texel offset.
// Also zero's off screen.
vec3 Fetch(vec2 pos,vec2 off){
pos=vTexCoord;//(floor(pos*global.REFERENCESize.xy+off)+vec2(0.5,0.5)) * global.REFERENCESize.zw;
return brightboost * texture(REFERENCE,pos.xy).rgb;
}
// Distance in emulated pixels to nearest texel.
vec2 Dist(vec2 pos){pos=pos*global.REFERENCESize.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);}
void main()
{
FragColor = vec4(Horz3(vTexCoord, -1.0).rgb, 1.0);
}