slang-shaders/crt/shaders/mame_hlsl/shaders/mame_distortion.slang

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#version 450
// license:BSD-3-Clause
// copyright-holders:ImJezze
//-----------------------------------------------------------------------------
// Distortion Effect
//-----------------------------------------------------------------------------
layout(push_constant) uniform Push
{
vec4 SourceSize;
vec4 OriginalSize;
vec4 OutputSize;
uint FrameCount;
vec4 FinalViewportSize;
} params;
#include "mame_parameters.inc"
#pragma stage vertex
layout(location = 0) in vec4 Position;
layout(location = 1) in vec2 TexCoord;
layout(location = 0) out vec2 v_texcoord0;
void main()
{
gl_Position = global.MVP * Position;
v_texcoord0 = TexCoord;
}
#pragma stage fragment
layout(location = 0) in vec2 v_texcoord0;
layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D Source;
vec4 u_distortion = vec4(global.distortion_amount);
vec4 u_cubic_distortion = vec4(global.cubic_distortion_amount);
vec4 u_distort_corner = vec4(global.distort_corner_amount);
vec4 u_round_corner = vec4(global.round_corner_amount);
vec4 u_smooth_border = vec4(global.smooth_border_amount);
vec4 u_vignetting = vec4(global.vignette_amount);
vec4 u_reflection = vec4(global.reflection_amount);
#define s_tex Source
#define saturate(c) clamp(c, 0., 1.)
// Functions
// www.stackoverflow.com/questions/5149544/can-i-generate-a-random-number-inside-a-pixel-shader/
float rand(vec2 seed)
{
// irrationals for pseudo randomness
vec2 i = vec2(23.140692, 2.6651442); // e^pi (Gelfond constant), 2^sqrt(2) (Gelfond-Schneider constant)
return fract(cos(dot(seed, i)) * 123456.0);
}
// www.dinodini.wordpress.com/2010/04/05/normalized-tunable-sigmoid-functions/
float normalizedSigmoid(float n, float k)
{
// valid for n and k in range of -1.0 and 1.0
return (n - n * k) / (k - abs(n) * 2.0 * k + 1.0);
}
// www.iquilezles.org/www/articles/distfunctions/distfunctions.htm
float roundBox(vec2 p, vec2 b, float r)
{
return length(max(abs(p) - b + r, 0.0)) - r;
}
float GetNoiseFactor(float n, float random)
{
// smaller n become more noisy
return 1.0 + random * max(0.0, 0.25 * pow(2.7182817, -8.0 * n));
}
float GetVignetteFactor(vec2 coord, float amount)
{
vec2 VignetteCoord = coord;
float VignetteLength = length(VignetteCoord);
float VignetteBlur = (amount * 0.75) + 0.25;
// 0.5 full screen fitting circle
float VignetteRadius = 1.0 - (amount * 0.25);
float Vignette = smoothstep(VignetteRadius, VignetteRadius - VignetteBlur, VignetteLength);
return saturate(Vignette);
}
float GetSpotAddend(vec2 coord, float amount)
{
vec2 SpotCoord = coord;
// upper right quadrant
vec2 spotOffset = vec2(-0.25, 0.25);
// normalized screen canvas ratio
vec2 CanvasRatio = ((u_swap_xy.x > 0.0) ? vec2(1.0, u_quad_dims.x / u_quad_dims.y) : vec2(1.0, u_quad_dims.y / u_quad_dims.x));
SpotCoord += spotOffset;
SpotCoord *= CanvasRatio;
float SpotBlur = amount;
// 0.5 full screen fitting circle
float SpotRadius = amount * 0.75;
float Spot = smoothstep(SpotRadius, SpotRadius - SpotBlur, length(SpotCoord));
float SigmoidSpot = amount * normalizedSigmoid(Spot, 0.75);
// increase strength by 100%
SigmoidSpot = SigmoidSpot * 2.0;
return saturate(SigmoidSpot);
}
float GetBoundsFactor(vec2 coord, vec2 bounds, float radiusAmount, float smoothAmount)
{
// reduce smooth amount down to radius amount
smoothAmount = min(smoothAmount, radiusAmount);
float range = min(bounds.x, bounds.y);
float amountMinimum = range > 0.0f ? 1.0f / range : 0.0f;
float radius = range * max(radiusAmount, amountMinimum);
float smooth_val = 1.0f / (range * max(smoothAmount, amountMinimum * 2.0f));
// compute box
float box = roundBox(bounds * (coord * 2.0f), bounds, radius);
// apply smooth
box *= smooth_val;
box += 1.0 - pow(smooth_val * 0.5, 0.5);
float border = smoothstep(1.0, 0.0, box);
return saturate(border);
}
// www.francois-tarlier.com/blog/cubic-lens-distortion-shader/
vec2 GetDistortedCoords(vec2 centerCoord, float amount, float amountCube)
{
// lens distortion coefficient
float k = amount;
// cubic distortion value
float kcube = amountCube;
// compute cubic distortion factor
float r2 = centerCoord.x * centerCoord.x + centerCoord.y * centerCoord.y;
float f = kcube == 0.0 ? 1.0 + r2 * k : 1.0 + r2 * (k + kcube * sqrt(r2));
// fit screen bounds
f /= 1.0 + amount * 0.25 + amountCube * 0.125;
// apply cubic distortion factor
centerCoord *= f;
return centerCoord;
}
vec2 GetTextureCoords(vec2 coord, float distortionAmount, float cubicDistortionAmount)
{
// center coordinates
coord -= 0.5;
// distort coordinates
coord = GetDistortedCoords(coord, distortionAmount, cubicDistortionAmount);
// un-center coordinates
coord += 0.5;
return coord;
}
vec2 GetQuadCoords(vec2 coord, vec2 scale, float distortionAmount, float cubicDistortionAmount)
{
// center coordinates
coord -= 0.5;
// apply scale
coord *= scale;
// distort coordinates
coord = GetDistortedCoords(coord, distortionAmount, cubicDistortionAmount);
return coord;
}
float noise(vec2 p){
vec2 ip = floor(p);
vec2 u = fract(p);
u = u*u*(3.0-2.0*u);
float res = mix(
mix(rand(ip),rand(ip+vec2(1.0,0.0)),u.x),
mix(rand(ip+vec2(0.0,1.0)),rand(ip+vec2(1.0,1.0)),u.x),u.y);
return res*res;
}
vec2 noisecoord(vec2 coord){
float offset_x = noise(sin(gl_FragCoord.xy) * float(mod(params.FrameCount + 873, 3061.)));
float offset_y = noise(cos(gl_FragCoord.yx) * float(mod(params.FrameCount + 2157, 8703.)));
return coord + vec2(offset_x, offset_y) * 0.001 * global.noise_amt;
}
void main()
{
if (!Distortion)
{
FragColor = texture(s_tex, v_texcoord0);
}
else
{
float distortionAmount = u_distortion.x;
float cubicDistortionAmount = u_cubic_distortion.x > 0.0
? u_cubic_distortion.x * 1.1 // cubic distortion need to be a little higher to compensate the quartic distortion
: u_cubic_distortion.x * 1.2; // negativ values even more
// corner distortion at least by the amount of the image distorition
float distortCornerAmount = max(u_distort_corner.x, u_distortion.x + u_cubic_distortion.x);
float roundCornerAmount = u_round_corner.x * 0.5;
float smoothBorderAmount = u_smooth_border.x * 0.5;
vec2 TexelDims = vec2(1.0 / u_target_dims.x, 1.0 / u_target_dims.y);
// base-target dimensions (without oversampling)
vec2 BaseTargetDims = u_target_dims.xy / u_target_scale.xy;
BaseTargetDims = (u_swap_xy.x > 0.0)
? BaseTargetDims.yx
: BaseTargetDims.xy;
// base-target/quad difference scale
vec2 BaseTargetQuadScale = (u_screen_count.x > 0.0 && u_screen_count.x < 2.0)
? BaseTargetDims / u_quad_dims.xy // keeps the coords inside of the quad bounds of a single screen
: vec2(1.0, 1.0);
// Screen Texture Curvature
vec2 BaseCoord = GetTextureCoords(v_texcoord0, distortionAmount, cubicDistortionAmount);
BaseCoord = noisecoord(BaseCoord);
// Screen Quad Curvature
vec2 QuadCoord = GetQuadCoords(v_texcoord0, BaseTargetQuadScale, distortCornerAmount, 0.0);
// Color
vec4 BaseColor = texture(s_tex, BaseCoord);
// Clamp
if (BaseCoord.x > 1.0 + TexelDims.x || BaseCoord.y > 1.0 + TexelDims.y || BaseCoord.x < 0.0 - TexelDims.x || BaseCoord.y < 0.0 - TexelDims.y)
{
FragColor = vec4(0.0, 0.0, 0.0, 0.0);
}
else
{
// Vignetting Simulation
vec2 VignetteCoord = QuadCoord;
float VignetteFactor = GetVignetteFactor(VignetteCoord, u_vignetting.x);
BaseColor.rgb *= VignetteFactor;
// Light Reflection Simulation
vec4 LightColor = vec4(1.0, 0.90, 0.80, 1.0); // color temperature 5.000 Kelvin
vec2 SpotCoord = QuadCoord;
vec2 NoiseCoord = QuadCoord;
float SpotAddend = GetSpotAddend(SpotCoord, u_reflection.x);
float NoiseFactor = GetNoiseFactor(SpotAddend, rand(NoiseCoord));
BaseColor += SpotAddend * NoiseFactor * LightColor;
// Round Corners Simulation
vec2 RoundCornerCoord = QuadCoord;
vec2 RoundCornerBounds = (u_screen_count.x > 0.0 && u_screen_count.x < 2.0)
? u_quad_dims.xy // align corners to screen quad bounds
: BaseTargetDims; // align corners to target texture bounds
RoundCornerBounds = (u_swap_xy.x > 0.0)
? RoundCornerBounds.yx
: RoundCornerBounds.xy;
float roundCornerFactor = GetBoundsFactor(RoundCornerCoord, RoundCornerBounds, roundCornerAmount, smoothBorderAmount);
BaseColor.rgb *= roundCornerFactor;
FragColor = BaseColor;
}
}
}