I was bored, trying to get the hang of slang shaders and inspired by @hunterk’s recent updates to geom shader family. Thought I’d try to add parameters to the settings in crt-interlaced-halation.

Everything seems to be working fine. Haven’t been able to test the Interlace toggle/detection. Scanline strength only works if GUASSIAN is commented out. Halation has no strength setting because of how its implemented in this shader (at least I didn’t see where to add it.)

Use this instead of the current crt-interlaced-halation-pass2.slang:

```
#version 450
layout(push_constant) uniform Push
{
vec4 SourceSize;
vec4 OriginalSize;
vec4 OutputSize;
uint FrameCount;
float CRTgamma;
float monitorgamma;
float d;
float R;
float cornersize;
float cornersmooth;
float x_tilt;
float y_tilt;
float overscan_x;
float overscan_y;
float DOTMASK;
float SHARPER;
float scanline_weight;
float CURVATURE;
float interlace_detect;
float lum;
} params;
layout(std140, set = 0, binding = 0) uniform UBO
{
mat4 MVP;
} global;
#pragma parameter CRTgamma "CRTGeom Target Gamma" 2.4 0.1 5.0 0.1
#pragma parameter monitorgamma "CRTGeom Monitor Gamma" 2.2 0.1 5.0 0.1
#pragma parameter d "CRTGeom Distance" 1.5 0.1 3.0 0.1
#pragma parameter CURVATURE "CRTGeom Curvature Toggle" 1.0 0.0 1.0 1.0
#pragma parameter R "CRTGeom Curvature Radius" 2.0 0.1 10.0 0.1
#pragma parameter cornersize "CRTGeom Corner Size" 0.03 0.001 1.0 0.005
#pragma parameter cornersmooth "CRTGeom Corner Smoothness" 1000.0 80.0 2000.0 100.0
#pragma parameter x_tilt "CRTGeom Horizontal Tilt" 0.0 -0.5 0.5 0.05
#pragma parameter y_tilt "CRTGeom Vertical Tilt" 0.0 -0.5 0.5 0.05
#pragma parameter overscan_x "CRTGeom Horiz. Overscan %" 100.0 -125.0 125.0 1.0
#pragma parameter overscan_y "CRTGeom Vert. Overscan %" 100.0 -125.0 125.0 1.0
#pragma parameter DOTMASK "CRTGeom Dot Mask Strength" 0.3 0.0 1.0 0.05
#pragma parameter SHARPER "CRTGeom Sharpness" 1.0 1.0 3.0 1.0
#pragma parameter scanline_weight "CRTGeom Scanline Weight" 0.3 0.1 0.5 0.05
#pragma parameter lum "CRTGeom Luminance" 0.0 0.0 1.0 0.01
#pragma parameter interlace_detect "CRTGeom Interlacing Simulation" 1.0 0.0 1.0 1.0
float CRTgamma = params.CRTgamma;
float monitorgamma = params.monitorgamma;
float d = params.d;
float R = params.R;
float cornersize = params.cornersize;
float cornersmooth = params.cornersmooth;
float x_tilt = params.x_tilt;
float y_tilt = params.y_tilt;
float overscan_x = params.overscan_x;
float overscan_y = params.overscan_y;
float DOTMASK = params.DOTMASK;
float SHARPER = params.SHARPER;
float scanline_weight = params.scanline_weight;
float CURVATURE = params.CURVATURE;
float interlace_detect = params.interlace_detect;
float lum = params.lum;
/*
CRT-interlaced-halation shader - pass2
Like the CRT-interlaced shader, but adds a subtle glow around bright areas
of the screen.
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
"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."
)
*/
// Comment the next line to disable interpolation in linear gamma (and
// gain speed).
#define LINEAR_PROCESSING
// Enable 3x oversampling of the beam profile
//#define OVERSAMPLE
// Use the older, purely gaussian beam profile
#define USEGAUSSIAN
//Enable if using several shaders.
//Disabling it reduces moire for single pass.
#define MULTIPASS
// Macros.
#define FIX(c) max(abs(c), 1e-5);
#define PI 3.141592653589
#ifdef LINEAR_PROCESSING
# define TEX2D(c) pow(texture(Original, (c)), vec4(CRTgamma))
#else
# define TEX2D(c) texture(Original, (c))
#endif
vec2 aspect = vec2(1.0, 0.75);
float intersect(vec2 xy, vec2 sinangle, vec2 cosangle)
{
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);
}
vec2 bkwtrans(vec2 xy, vec2 sinangle, vec2 cosangle)
{
float c = intersect(xy, sinangle, cosangle);
vec2 point = vec2(c)*xy;
point -= vec2(-R)*sinangle;
point /= vec2(R);
vec2 tang = sinangle/cosangle;
vec2 poc = point/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);
}
vec2 fwtrans(vec2 uv, vec2 sinangle, vec2 cosangle)
{
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;
}
vec3 maxscale(vec2 sinangle, vec2 cosangle)
{
vec2 c = bkwtrans(-R * sinangle / (1.0 + R/d*cosangle.x*cosangle.y), sinangle, cosangle);
vec2 a = vec2(0.5,0.5)*aspect;
vec2 lo = vec2(fwtrans(vec2(-a.x,c.y), sinangle, cosangle).x,
fwtrans(vec2(c.x,-a.y), sinangle, cosangle).y)/aspect;
vec2 hi = vec2(fwtrans(vec2(+a.x,c.y), sinangle, cosangle).x,
fwtrans(vec2(c.x,+a.y), sinangle, cosangle).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 (lum + 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 (lum + 1.4) * exp(-pow(weights * inversesqrt(0.5 * wid), wid)) / (0.6 + 0.2 * wid);
#endif
}
#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 one;
layout(location = 2) out float mod_factor;
layout(location = 3) out vec2 ilfac;
layout(location = 4) out vec3 stretch;
layout(location = 5) out vec2 sinangle;
layout(location = 6) out vec2 cosangle;
layout(location = 7) out vec2 TextureSize;
void main()
{
gl_Position = global.MVP * Position;
vTexCoord = TexCoord;
// 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(sinangle, cosangle);
TextureSize = vec2(SHARPER * params.SourceSize.x, params.SourceSize.y);
ilfac = vec2(1.0,clamp(floor(params.SourceSize.y/200.0),1.0,2.0));
// 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 * params.SourceSize.x * params.OutputSize.x / params.SourceSize.x;
}
#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
layout(location = 1) in vec2 one;
layout(location = 2) in float mod_factor;
layout(location = 3) in vec2 ilfac;
layout(location = 4) in vec3 stretch;
layout(location = 5) in vec2 sinangle;
layout(location = 6) in vec2 cosangle;
layout(location = 7) in vec2 TextureSize;
layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D Source;
layout(set = 0, binding = 3) uniform sampler2D Original;
#define mul(a, b) (b * a)
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.
vec2 xy, cd;
if (CURVATURE > 0.5)
{
cd = vTexCoord;
cd = (cd-vec2(0.5))*aspect*stretch.z+stretch.xy;
xy = (bkwtrans(cd, sinangle, cosangle)/vec2(overscan_x / 100.0, overscan_y / 100.0)/aspect+vec2(0.5,0.5));// * ORIG.video_size / ORIG.texture_size;
} else
{
xy = vTexCoord;
}
vec2 cd2 = xy;
//cd2 *= ORIG.texture_size / ORIG.video_size;
cd2 = (cd2 - vec2(0.5)) * vec2(overscan_x / 100.0, overscan_y / 100.0) + vec2(0.5, 0.5);
cd2 = min(cd2, vec2(1.0)-cd2) * aspect;
vec2 cdist = vec2(cornersize);
cd2 = (cdist - min(cd2,cdist));
float dist = sqrt(dot(cd2,cd2));
float cval = clamp((cdist.x-dist)*cornersmooth,0.0, 1.0);
vec2 xy2 = ((xy-vec2(0.5))*vec2(1.0,1.0)+vec2(0.5));//*IN.video_size/IN.texture_size;
// Of all the pixels that are mapped onto the texel we are
// currently rendering, which pixel are we currently rendering?
vec2 ilfloat = vec2(0.0,ilfac.y > 1.5 ? mod(vec2(params.FrameCount,params.FrameCount).x,2.0) : 0.0);
vec2 ratio_scale = (xy * TextureSize - vec2(0.5, 0.5) + ilfloat)/ilfac;
#ifdef OVERSAMPLE
//float filter = fwidth(ratio_scale.y);
float os_filter = params.SourceSize.y / params.OutputSize.y;
#endif
vec2 uv_ratio = fract(ratio_scale);
// Snap to the center of the underlying texel.
xy = (floor(ratio_scale)*ilfac + vec2(0.5, 0.5) - ilfloat) / 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(mul(coeffs, mat4x4(
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)))),
0.0, 1.0);
vec4 col2 = clamp(mul(coeffs, mat4x4(
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)))),
0.0, 1.0);
#ifndef LINEAR_PROCESSING
col = pow(col , vec4(CRTgamma));
col2 = pow(col2, vec4(CRTgamma));
#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);
#ifdef OVERSAMPLE
uv_ratio.y =uv_ratio.y+1.0/3.0*os_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*os_filter;
weights=weights+scanlineWeights(abs(uv_ratio.y), col)/3.0;
weights2=weights2+scanlineWeights(abs(1.0-uv_ratio.y), col2)/3.0;
#endif
vec3 mul_res = (col * weights + col2 * weights2).rgb;
#ifdef MULTIPASS
mul_res += pow(texture(Source, xy2).rgb, vec3(monitorgamma))*0.1;
#endif
mul_res *= 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));
// Color the texel.
FragColor = vec4(mul_res, 1.0);
}
```