Tonemapping.cginc
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#ifndef __TONEMAPPING__
#define __TONEMAPPING__
#include "ACES.cginc"
// Set to 1 to use the full reference ACES tonemapper. This should only be used for research
// purposes and it's quite heavy and generally overkill.
#define TONEMAPPING_USE_FULL_ACES 0
//
// Neutral tonemapping (Hable/Hejl/Frostbite)
// Input is linear RGB
//
half3 NeutralCurve(half3 x, half a, half b, half c, half d, half e, half f)
{
return ((x * (a * x + c * b) + d * e) / (x * (a * x + b) + d * f)) - e / f;
}
half3 NeutralTonemap(half3 x, half4 params1, half4 params2)
{
// ACES supports negative color values and WILL output negative values when coming from ACES or ACEScg
// Make sure negative channels are clamped to 0.0 as this neutral tonemapper can't deal with them properly
x = max((0.0).xxx, x);
// Tonemap
half a = params1.x;
half b = params1.y;
half c = params1.z;
half d = params1.w;
half e = params2.x;
half f = params2.y;
half whiteLevel = params2.z;
half whiteClip = params2.w;
half3 whiteScale = (1.0).xxx / NeutralCurve(whiteLevel, a, b, c, d, e, f);
x = NeutralCurve(x * whiteScale, a, b, c, d, e, f);
x *= whiteScale;
// Post-curve white point adjustment
x /= whiteClip.xxx;
return x;
}
//
// Filmic tonemapping (ACES fitting, unless TONEMAPPING_USE_FULL_ACES is set to 1)
// Input is ACES2065-1 (AP0 w/ linear encoding)
//
half3 FilmicTonemap(half3 aces)
{
#if TONEMAPPING_USE_FULL_ACES
half3 oces = RRT(aces);
half3 odt = ODT_RGBmonitor_100nits_dim(oces);
return odt;
#else
// --- Glow module --- //
half saturation = rgb_2_saturation(aces);
half ycIn = rgb_2_yc(aces);
half s = sigmoid_shaper((saturation - 0.4) / 0.2);
half addedGlow = 1.0 + glow_fwd(ycIn, RRT_GLOW_GAIN * s, RRT_GLOW_MID);
aces *= addedGlow;
// --- Red modifier --- //
half hue = rgb_2_hue(aces);
half centeredHue = center_hue(hue, RRT_RED_HUE);
half hueWeight;
{
//hueWeight = cubic_basis_shaper(centeredHue, RRT_RED_WIDTH);
hueWeight = Pow2(smoothstep(0.0, 1.0, 1.0 - abs(2.0 * centeredHue / RRT_RED_WIDTH)));
}
aces.r += hueWeight * saturation * (RRT_RED_PIVOT - aces.r) * (1.0 - RRT_RED_SCALE);
// --- ACES to RGB rendering space --- //
half3 acescg = max(0.0, ACES_to_ACEScg(aces));
// --- Global desaturation --- //
//acescg = mul(RRT_SAT_MAT, acescg);
acescg = lerp(dot(acescg, AP1_RGB2Y).xxx, acescg, RRT_SAT_FACTOR.xxx);
// Luminance fitting of *RRT.a1.0.3 + ODT.Academy.RGBmonitor_100nits_dim.a1.0.3*.
// https://github.com/colour-science/colour-unity/blob/master/Assets/Colour/Notebooks/CIECAM02_Unity.ipynb
// RMSE: 0.0012846272106
const half a = 278.5085;
const half b = 10.7772;
const half c = 293.6045;
const half d = 88.7122;
const half e = 80.6889;
half3 x = acescg;
half3 rgbPost = (x * (a * x + b)) / (x * (c * x + d) + e);
// Scale luminance to linear code value
// half3 linearCV = Y_2_linCV(rgbPost, CINEMA_WHITE, CINEMA_BLACK);
// Apply gamma adjustment to compensate for dim surround
half3 linearCV = darkSurround_to_dimSurround(rgbPost);
// Apply desaturation to compensate for luminance difference
//linearCV = mul(ODT_SAT_MAT, color);
linearCV = lerp(dot(linearCV, AP1_RGB2Y).xxx, linearCV, ODT_SAT_FACTOR.xxx);
// Convert to display primary encoding
// Rendering space RGB to XYZ
half3 XYZ = mul(AP1_2_XYZ_MAT, linearCV);
// Apply CAT from ACES white point to assumed observer adapted white point
XYZ = mul(D60_2_D65_CAT, XYZ);
// CIE XYZ to display primaries
linearCV = mul(XYZ_2_REC709_MAT, XYZ);
return linearCV;
#endif
}
#endif // __TONEMAPPING__