slang-shaders/crt/shaders/hyllian/crt-hyllian-multipass/crt-hyllian-pass0.slang

#version 450

/*
   Hyllian's CRT Shader - pass0
  
   Copyright (C) 2011-2016 Hyllian - sergiogdb@gmail.com
   Permission is hereby granted, free of charge, to any person obtaining a copy
   of this software and associated documentation files (the "Software"), to deal
   in the Software without restriction, including without limitation the rights
   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   copies of the Software, and to permit persons to whom the Software is
   furnished to do so, subject to the following conditions:
   The above copyright notice and this permission notice shall be included in
   all copies or substantial portions of the Software.
   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   THE SOFTWARE.
*/

layout(push_constant) uniform Push
{
	vec4 SourceSize;
	vec4 OriginalSize;
	vec4 OutputSize;
	uint FrameCount;
	float SHARPNESS;
	float CRT_ANTI_RINGING;
	float InputGamma;
} params;

#pragma parameter SHARPNESS "CRT - Sharpness Hack" 1.0 1.0 5.0 1.0
#pragma parameter CRT_ANTI_RINGING "CRT - Anti-Ringing" 0.8 0.0 1.0 0.1
#pragma parameter InputGamma "CRT - Input gamma" 2.5 0.0 5.0 0.1

#define SHARPNESS params.SHARPNESS
#define CRT_ANTI_RINGING params.CRT_ANTI_RINGING
#define InputGamma params.InputGamma

layout(std140, set = 0, binding = 0) uniform UBO
{
	mat4 MVP;
} global;

#define GAMMA_IN(color)    pow(color, vec3(InputGamma, InputGamma, InputGamma))

// Horizontal cubic filter.

// Some known filters use these values:

//   B = 0.0, C = 0.0  =>  Hermite cubic filter.
//   B = 1.0, C = 0.0  =>  Cubic B-Spline filter.
//   B = 0.0, C = 0.5  =>  Catmull-Rom Spline filter. This is the default used in this shader.
//   B = C = 1.0/3.0   =>  Mitchell-Netravali cubic filter.
//   B = 0.3782, C = 0.3109  =>  Robidoux filter.
//   B = 0.2620, C = 0.3690  =>  Robidoux Sharp filter.
//   B = 0.36, C = 0.28  =>  My best config for ringing elimination in pixel art (Hyllian).


// For more info, see: http://www.imagemagick.org/Usage/img_diagrams/cubic_survey.gif

// Change these params to configure the horizontal filter.
const  float  B =  0.0; 
const  float  C =  0.5;  

const  mat4 invX = mat4(                    (-B - 6.0*C)/6.0,   (12.0 - 9.0*B - 6.0*C)/6.0,  -(12.0 - 9.0*B - 6.0*C)/6.0,   (B + 6.0*C)/6.0,
                                   (3.0*B + 12.0*C)/6.0, (-18.0 + 12.0*B + 6.0*C)/6.0, (18.0 - 15.0*B - 12.0*C)/6.0,            -C,
                                   (-3.0*B - 6.0*C)/6.0,                    0.0,        (3.0*B + 6.0*C)/6.0,            0.0,
                                              B/6.0,         (6.0 - 2.0*B)/6.0,                  B/6.0,            0.0);


#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;

void main()
{
   vec2 texture_size = vec2(SHARPNESS*params.SourceSize.x, params.SourceSize.y);

   vec3 color;
   vec2 dx = vec2(1.0/texture_size.x, 0.0);
   vec2 dy = vec2(0.0, 1.0/texture_size.y);
   vec2 pix_coord = vTexCoord*texture_size+vec2(-0.5,0.0);

   vec2 tc = (floor(pix_coord)+vec2(0.5,0.001))/texture_size;

   vec2 fp = fract(pix_coord);

   vec3 c10 = GAMMA_IN(texture(Source, tc    - dx).xyz);
   vec3 c11 = GAMMA_IN(texture(Source, tc       ).xyz);
   vec3 c12 = GAMMA_IN(texture(Source, tc    + dx).xyz);
   vec3 c13 = GAMMA_IN(texture(Source, tc + 2.0*dx).xyz);

   //  Get min/max samples
   vec3 min_sample = min(c11,c12);
   vec3 max_sample = max(c11,c12);

   mat4x3 color_matrix = mat4x3(c10, c11, c12, c13);

   vec4 lobes = vec4(fp.x*fp.x*fp.x, fp.x*fp.x, fp.x, 1.0);

   vec4 invX_Px  = invX * lobes;
   color       = color_matrix * invX_Px;

   // Anti-ringing
   vec3 aux = color;
   color = clamp(color, min_sample, max_sample);
   color = mix(aux, color, CRT_ANTI_RINGING);
   FragColor = vec4(color, 1.0);
}