slang-shaders/crt/shaders/crt-geom.slang

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#version 450
layout(std140, set = 0, binding = 0) uniform UBO
{
mat4 MVP;
vec4 OutputSize;
vec4 OriginalSize;
vec4 SourceSize;
uint FrameCount;
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} global;
#define CRTgamma 2.4
#define monitorgamma 2.2
#define d 1.5
#define CURVATURE 1.0
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#define R 2.0
#define cornersize 0.03
#define cornersmooth 1000.0
#define x_tilt 0.0
#define y_tilt 0.0
#define overscan_x 100.0
#define overscan_y 100.0
#define DOTMASK 0.3
#define SHARPER 1.0
#define scanline_weight 0.3
/*
CRT-interlaced
Copyright (C) 2010-2012 cgwg, Themaister and DOLLS
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.
(cgwg gave their consent to have the original version of this shader
distributed under the GPL in this message:
http://board.byuu.org/viewtopic.php?p=26075#p26075
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"Feel free to distribute my shaders under the GPL. After all, the
barrel distortion code was taken from the Curvature shader, which is
under the GPL."
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)
This shader variant is pre-configured with screen curvature
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*/
// Comment the next line to disable interpolation in linear gamma (and
// gain speed).
#define LINEAR_PROCESSING
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// Enable 3x oversampling of the beam profile; improves moire effect caused by scanlines+curvature
#define OVERSAMPLE
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// Use the older, purely gaussian beam profile; uncomment for speed
#define USEGAUSSIAN
// Use interlacing detection; may interfere with other shaders if combined
#define INTERLACED
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// Macros.
#define FIX(c) max(abs(c), 1e-5);
#define PI 3.141592653589
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#ifdef LINEAR_PROCESSING
# define TEX2D(c) pow(texture(Source, (c)), vec4(CRTgamma))
#else
# define TEX2D(c) texture(Source, (c))
#endif
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// aspect ratio
vec2 aspect = vec2(1.0, 0.75);
vec2 overscan = vec2(1.01, 1.01);
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#pragma stage vertex
layout(location = 0) in vec4 Position;
layout(location = 1) in vec2 TexCoord;
layout(location = 0) out vec2 vTexCoord;
layout(location = 1) out vec2 sinangle;
layout(location = 2) out vec2 cosangle;
layout(location = 3) out vec3 stretch;
layout(location = 4) out vec2 ilfac;
layout(location = 5) out vec2 one;
layout(location = 6) out float mod_factor;
layout(location = 7) out vec2 TextureSize;
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float intersect(vec2 xy)
{
float A = dot(xy,xy) + d*d;
float B = 2.0*(R*(dot(xy,sinangle)-d*cosangle.x*cosangle.y)-d*d);
float C = d*d + 2.0*R*d*cosangle.x*cosangle.y;
return (-B-sqrt(B*B-4.0*A*C))/(2.0*A);
}
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vec2 bkwtrans(vec2 xy)
{
float c = intersect(xy);
vec2 point = (vec2(c, c)*xy - vec2(-R, -R)*sinangle) / vec2(R, R);
vec2 poc = point/cosangle;
vec2 tang = sinangle/cosangle;
float A = dot(tang, tang) + 1.0;
float B = -2.0*dot(poc, tang);
float C = dot(poc, poc) - 1.0;
float a = (-B + sqrt(B*B - 4.0*A*C))/(2.0*A);
vec2 uv = (point - a*sinangle)/cosangle;
float r = FIX(R*acos(a));
return uv*r/sin(r/R);
}
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vec2 fwtrans(vec2 uv)
{
float r = FIX(sqrt(dot(uv,uv)));
uv *= sin(r/R)/r;
float x = 1.0-cos(r/R);
float D = d/R + x*cosangle.x*cosangle.y+dot(uv,sinangle);
return d*(uv*cosangle-x*sinangle)/D;
}
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vec3 maxscale()
{
vec2 c = bkwtrans(-R * sinangle / (1.0 + R/d*cosangle.x*cosangle.y));
vec2 a = vec2(0.5,0.5)*aspect;
vec2 lo = vec2(fwtrans(vec2(-a.x, c.y)).x,
fwtrans(vec2( c.x, -a.y)).y)/aspect;
vec2 hi = vec2(fwtrans(vec2(+a.x, c.y)).x,
fwtrans(vec2( c.x, +a.y)).y)/aspect;
return vec3((hi+lo)*aspect*0.5,max(hi.x-lo.x,hi.y-lo.y));
}
// Calculate the influence of a scanline on the current pixel.
//
// 'distance' is the distance in texture coordinates from the current
// pixel to the scanline in question.
// 'color' is the colour of the scanline at the horizontal location of
// the current pixel.
vec4 scanlineWeights(float distance, vec4 color)
{
// "wid" controls the width of the scanline beam, for each RGB
// channel The "weights" lines basically specify the formula
// that gives you the profile of the beam, i.e. the intensity as
// a function of distance from the vertical center of the
// scanline. In this case, it is gaussian if width=2, and
// becomes nongaussian for larger widths. Ideally this should
// be normalized so that the integral across the beam is
// independent of its width. That is, for a narrower beam
// "weights" should have a higher peak at the center of the
// scanline than for a wider beam.
#ifdef USEGAUSSIAN
vec4 wid = 0.3 + 0.1 * pow(color, vec4(3.0));
vec4 weights = vec4(distance / wid);
return 0.4 * exp(-weights * weights) / wid;
#else
vec4 wid = 2.0 + 2.0 * pow(color, vec4(4.0));
vec4 weights = vec4(distance / scanline_weight);
return 1.4 * exp(-pow(weights * inversesqrt(0.5 * wid), wid)) / (0.6 + 0.2 * wid);
#endif
}
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void main()
{
gl_Position = global.MVP * Position;
vTexCoord = TexCoord * vec2(1.00001);
// Precalculate a bunch of useful values we'll need in the fragment
// shader.
sinangle = sin(vec2(x_tilt, y_tilt));
cosangle = cos(vec2(x_tilt, y_tilt));
stretch = maxscale();
TextureSize = vec2(SHARPER * global.SourceSize.x, global.SourceSize.y);
#ifdef INTERLACED
ilfac = vec2(1.0, clamp(floor(global.SourceSize.y/200.0), 1.0, 2.0));
#else
ilfac = vec2(1.0, clamp(floor(global.SourceSize.y/1000.0), 1.0, 2.0));
#endif
// The size of one texel, in texture-coordinates.
one = ilfac / TextureSize;
// Resulting X pixel-coordinate of the pixel we're drawing.
mod_factor = vTexCoord.x * global.SourceSize.x * global.OutputSize.x / global.SourceSize.x;
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}
#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
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layout(location = 1) in vec2 sinangle;
layout(location = 2) in vec2 cosangle;
layout(location = 3) in vec3 stretch;
layout(location = 4) in vec2 ilfac;
layout(location = 5) in vec2 one;
layout(location = 6) in float mod_factor;
layout(location = 7) in vec2 TextureSize;
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layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D Source;
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float intersect(vec2 xy)
{
float A = dot(xy,xy) + d*d;
float B = 2.0*(R*(dot(xy,sinangle) - d*cosangle.x*cosangle.y) - d*d);
float C = d*d + 2.0*R*d*cosangle.x*cosangle.y;
return (-B-sqrt(B*B - 4.0*A*C))/(2.0*A);
}
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vec2 bkwtrans(vec2 xy)
{
float c = intersect(xy);
vec2 point = (vec2(c, c)*xy - vec2(-R, -R)*sinangle) / vec2(R, R);
vec2 poc = point/cosangle;
vec2 tang = sinangle/cosangle;
float A = dot(tang, tang) + 1.0;
float B = -2.0*dot(poc, tang);
float C = dot(poc, poc) - 1.0;
float a = (-B + sqrt(B*B - 4.0*A*C)) / (2.0*A);
vec2 uv = (point - a*sinangle) / cosangle;
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float r = FIX(R*acos(a));
return uv*r/sin(r/R);
}
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vec2 fwtrans(vec2 uv)
{
float r = FIX(sqrt(dot(uv, uv)));
uv *= sin(r/R)/r;
float x = 1.0 - cos(r/R);
float D = d/R + x*cosangle.x*cosangle.y + dot(uv,sinangle);
return d*(uv*cosangle - x*sinangle)/D;
}
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vec3 maxscale()
{
vec2 c = bkwtrans(-R * sinangle / (1.0 + R/d*cosangle.x*cosangle.y));
vec2 a = vec2(0.5, 0.5)*aspect;
vec2 lo = vec2(fwtrans(vec2(-a.x, c.y)).x,
fwtrans(vec2( c.x, -a.y)).y)/aspect;
vec2 hi = vec2(fwtrans(vec2(+a.x, c.y)).x,
fwtrans(vec2( c.x, +a.y)).y)/aspect;
return vec3((hi+lo)*aspect*0.5,max(hi.x-lo.x, hi.y-lo.y));
}
// Calculate the influence of a scanline on the current pixel.
//
// 'distance' is the distance in texture coordinates from the current
// pixel to the scanline in question.
// 'color' is the colour of the scanline at the horizontal location of
// the current pixel.
vec4 scanlineWeights(float distance, vec4 color)
{
// "wid" controls the width of the scanline beam, for each RGB
// channel The "weights" lines basically specify the formula
// that gives you the profile of the beam, i.e. the intensity as
// a function of distance from the vertical center of the
// scanline. In this case, it is gaussian if width=2, and
// becomes nongaussian for larger widths. Ideally this should
// be normalized so that the integral across the beam is
// independent of its width. That is, for a narrower beam
// "weights" should have a higher peak at the center of the
// scanline than for a wider beam.
#ifdef USEGAUSSIAN
vec4 wid = 0.3 + 0.1 * pow(color, vec4(3.0));
vec4 weights = vec4(distance / wid);
return 0.4 * exp(-weights * weights) / wid;
#else
vec4 wid = 2.0 + 2.0 * pow(color, vec4(4.0));
vec4 weights = vec4(distance / scanline_weight);
return 1.4 * exp(-pow(weights * inversesqrt(0.5 * wid), wid)) / (0.6 + 0.2 * wid);
#endif
}
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vec2 transform(vec2 coord)
{
coord = (coord - vec2(0.5, 0.5))*aspect*stretch.z + stretch.xy;
return (bkwtrans(coord) /
vec2(overscan_x / 100.0, overscan_y / 100.0)/aspect + vec2(0.5, 0.5));
}
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float corner(vec2 coord)
{
coord = (coord - vec2(0.5)) * vec2(overscan_x / 100.0, overscan_y / 100.0) + vec2(0.5, 0.5);
coord = min(coord, vec2(1.0) - coord) * aspect;
vec2 cdist = vec2(cornersize);
coord = (cdist - min(coord, cdist));
float dist = sqrt(dot(coord, coord));
return clamp((cdist.x - dist)*cornersmooth, 0.0, 1.0);
}
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void main()
{
// Here's a helpful diagram to keep in mind while trying to
// understand the code:
//
// | | | | |
// -------------------------------
// | | | | |
// | 01 | 11 | 21 | 31 | <-- current scanline
// | | @ | | |
// -------------------------------
// | | | | |
// | 02 | 12 | 22 | 32 | <-- next scanline
// | | | | |
// -------------------------------
// | | | | |
//
// Each character-cell represents a pixel on the output
// surface, "@" represents the current pixel (always somewhere
// in the bottom half of the current scan-line, or the top-half
// of the next scanline). The grid of lines represents the
// edges of the texels of the underlying texture.
// Texture coordinates of the texel containing the active pixel.
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#ifdef CURVATURE
vec2 xy = transform(vTexCoord);
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#else
vec2 xy = vTexCoord;
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#endif
float cval = corner(xy);
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// Of all the pixels that are mapped onto the texel we are
// currently rendering, which pixel are we currently rendering?
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#ifdef INTERLACED
vec2 ilvec = vec2(0.0, ilfac.y > 1.5 ? mod(float(global.FrameCount), 2.0) : 0.0);
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#else
vec2 ilvec = vec2(0.0, ilfac.y);
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#endif
vec2 ratio_scale = (xy * TextureSize - vec2(0.5, 0.5) + ilvec) / ilfac;
vec2 uv_ratio = fract(ratio_scale);
// Snap to the center of the underlying texel.
xy = (floor(ratio_scale)*ilfac + vec2(0.5, 0.5) - ilvec) / TextureSize;
// Calculate Lanczos scaling coefficients describing the effect
// of various neighbour texels in a scanline on the current
// pixel.
vec4 coeffs = PI * vec4(1.0 + uv_ratio.x, uv_ratio.x, 1.0 - uv_ratio.x, 2.0 - uv_ratio.x);
// Prevent division by zero.
coeffs = FIX(coeffs);
// Lanczos2 kernel.
coeffs = 2.0 * sin(coeffs) * sin(coeffs / 2.0) / (coeffs * coeffs);
// Normalize.
coeffs /= dot(coeffs, vec4(1.0));
// Calculate the effective colour of the current and next
// scanlines at the horizontal location of the current pixel,
// using the Lanczos coefficients above.
vec4 col = clamp(
mat4(
TEX2D(xy + vec2(-one.x, 0.0)),
TEX2D(xy),
TEX2D(xy + vec2(one.x, 0.0)),
TEX2D(xy + vec2(2.0 * one.x, 0.0))
) * coeffs,
0.0, 1.0
);
vec4 col2 = clamp(
mat4(
TEX2D(xy + vec2(-one.x, one.y)),
TEX2D(xy + vec2(0.0, one.y)),
TEX2D(xy + one),
TEX2D(xy + vec2(2.0 * one.x, one.y))
) * coeffs,
0.0, 1.0
);
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#ifndef LINEAR_PROCESSING
col = pow(col , vec4(CRTgamma));
col2 = pow(col2, vec4(CRTgamma));
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#endif
// Calculate the influence of the current and next scanlines on
// the current pixel.
vec4 weights = scanlineWeights(uv_ratio.y, col);
vec4 weights2 = scanlineWeights(1.0 - uv_ratio.y, col2);
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#ifdef OVERSAMPLE
float filter_ = fwidth(ratio_scale.y);
uv_ratio.y = uv_ratio.y + 1.0/3.0*filter_;
weights = (weights + scanlineWeights(uv_ratio.y, col))/3.0;
weights2 = (weights2 + scanlineWeights(abs(1.0 - uv_ratio.y), col2))/3.0;
uv_ratio.y = uv_ratio.y - 2.0/3.0*filter_;
weights = weights + scanlineWeights(abs(uv_ratio.y), col)/3.0;
weights2 = weights2 + scanlineWeights(abs(1.0 - uv_ratio.y), col2)/3.0;
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#endif
vec3 mul_res = (col * weights + col2 * weights2).rgb * vec3(cval);
// dot-mask emulation:
// Output pixels are alternately tinted green and magenta.
vec3 dotMaskWeights = mix(
vec3(1.0, 1.0 - DOTMASK, 1.0),
vec3(1.0 - DOTMASK, 1.0, 1.0 - DOTMASK),
floor(mod(mod_factor, 2.0))
);
mul_res *= dotMaskWeights;
// Convert the image gamma for display on our output device.
mul_res = pow(mul_res, vec3(1.0 / monitorgamma));
FragColor = vec4(mul_res, 1.0);
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}