slang-shaders/ntsc/shaders/analog_overshoot.slang

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2022-09-28 01:17:59 +10:00
#version 450
// Analog Overshoot
// by Astherix
// adapted for slang from NTSC Codec (w/Overshoot & Noise) shadertoy
// https://www.shadertoy.com/view/flG3zd
// Licensed LGPLv3
// This pass applies a simulation of analog overshoot, which
// is the cause for ghosting artifacts around edges (sharp transitions)
// This is not necessary for encoding/decoding.
layout(push_constant) uniform Push
{
vec4 SourceSize;
vec4 OriginalSize;
vec4 OutputSize;
uint FrameCount;
float hermite_tension, hermite_bias, decode_chroma_luma_separately;
} params;
// These two define the tension and bias parameters
// of the Hermite interpolation function
// Values closer to 0.5 on both parameters yield
// more aggressive ghosting artifacts
#pragma parameter hermite_tension "Hermite Tension" 0.25 0.01 1.0 0.01
#pragma parameter hermite_bias "Hermite Bias" 0.75 0.01 1.0 0.01
#pragma parameter decode_chroma_luma_separately "Decode Chroma and Luma Separately" 1.0 0.0 1.0 1.0
#define DECODE_CHROMA_LUMA_SEPARATELY params.decode_chroma_luma_separately
#define HERMITE_TENSION params.hermite_tension
#define HERMITE_BIAS params.hermite_bias
#define iChannel0 Source
#define iResolution params.OutputSize.xy
#define fragCoord (vTexCoord.xy * params.OutputSize.xy)
#define fragColor FragColor
#define iFrame params.FrameCount
#define iTime (params.FrameCount / 60)
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 * 1.0001;
}
#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D Source;
float hermite(float y0, float y1, float y2, float y3, float m, float tension, float bias) {
float m2 = m*m,
m3 = m2*m,
m0 = (y1-y0)*(1.0+bias)*(1.0-tension)/2.0;
m0 = m0 + (y2-y1)*(1.0-bias)*(1.0-tension)/2.0;
float m1 = (y2-y1)*(1.0+bias)*(1.0-tension)/2.0;
m1 = m1 + (y3-y2)*(1.0-bias)*(1.0-tension)/2.0;
float a0 = 2.0*m3 - 3.0*m2 + 1.0,
a1 = m3 - 2.0*m2 + m,
a2 = m3 - m2,
a3 = -2.0*m3 + 3.0*m2;
return (a0*y1+a1*m0+a2*m1+a3*y2);
}
void main()
{
vec2 px = vTexCoord.xy * params.OutputSize.zw;
// Normalized pixel coordinates (from 0 to 1)
vec2 fcm1 = vec2(fragCoord.x-4.0, fragCoord.y)/iResolution.xy,
fcm0 = vec2(fragCoord.x-0.0, fragCoord.y)/iResolution.xy,
fcp1 = vec2(fragCoord.x+4.0, fragCoord.y)/iResolution.xy,
fcp2 = vec2(fragCoord.x+8.0, fragCoord.y)/iResolution.xy;
vec3 y0 = texture(Source, fcm1).xyz,
y1 = texture(Source, fcm0).xyz,
y2 = texture(Source, fcp1).xyz,
y3 = texture(Source, fcp2).xyz;
vec3 o = y1;
float l = HERMITE_TENSION, y = HERMITE_BIAS;
vec3 f = vec3(
hermite(y0.x, y1.x, y2.x, y3.x, l, y, y * 50.0),
hermite(y0.y, y1.y, y2.y, y3.y, l, y, y * 50.0),
hermite(y0.z, y1.z, y2.z, y3.z, l, y, y * 50.0)
);
fragColor = mix(vec4(f, 1.0), vec4(y1, 1.0), DECODE_CHROMA_LUMA_SEPARATELY);
}