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Add agx_white, agx_contrast and HDR support to the AgX tonemapper.

Browse source 
Also optimize all tonemappers to perform less calculations per-pixel.

Note: unlike `white`, `agx_white` is limited to a minimum of `2.0` and defaults to `16.29`. When using a RGB10A2 render buffer, `agx_white` will be ignored and a value of `2.0` will be used instead to ensure good behavior on the Mobile renderer.
This commit is contained in:
Allen Pestaluky 2025-05-29 12:19:00 -04:00
parent 7a228b4b91
commit 628df323e2
24 changed files with 546 additions and 241 deletions
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157
servers/rendering/renderer_rd/shaders/effects/tonemap.glsl
View file

@ -82,23 +82,26 @@ layout(push_constant, std430) uniform Params {
float white;
float auto_exposure_scale;
float luminance_multiplier;
vec4 tonemapper_params;
}
params;
layout(location = 0) out vec4 frag_color;
// Based on Reinhard's extended formula, see equation 4 in https://doi.org/cjbgrt
vec3 tonemap_reinhard(vec3 color, float white) {
float white_squared = white * white;
vec3 tonemap_reinhard(vec3 color) {
float white_squared = params.tonemapper_params.x;
vec3 white_squared_color = white_squared * color;
// Equivalent to color * (1 + color / white_squared) / (1 + color)
return (white_squared_color + color * color) / (white_squared_color + white_squared);
}
vec3 tonemap_filmic(vec3 color, float white) {
// exposure bias: input scale (color *= bias, white *= bias) to make the brightness consistent with other tonemappers
// also useful to scale the input to the range that the tonemapper is designed for (some require very high input values)
// has no effect on the curve's general shape or visual properties
vec3 tonemap_filmic(vec3 color) {
// These constants must match the those in the C++ code that calculates the parameters.
// exposure_bias: Input scale (color *= bias, env->white *= bias) to make the brightness consistent with other tonemappers.
// Also useful to scale the input to the range that the tonemapper is designed for (some require very high input values).
// Has no effect on the curve's general shape or visual properties.
const float exposure_bias = 2.0f;
const float A = 0.22f * exposure_bias * exposure_bias; // bias baked into constants for performance
const float B = 0.30f * exposure_bias;
@ -108,14 +111,14 @@ vec3 tonemap_filmic(vec3 color, float white) {
const float F = 0.30f;
vec3 color_tonemapped = ((color * (A * color + C * B) + D * E) / (color * (A * color + B) + D * F)) - E / F;
float white_tonemapped = ((white * (A * white + C * B) + D * E) / (white * (A * white + B) + D * F)) - E / F;
return color_tonemapped / white_tonemapped;
return color_tonemapped / params.tonemapper_params.x;
}
// Adapted from https://github.com/TheRealMJP/BakingLab/blob/master/BakingLab/ACES.hlsl
// (MIT License).
vec3 tonemap_aces(vec3 color, float white) {
vec3 tonemap_aces(vec3 color) {
// These constants must match the those in the C++ code that calculates the parameters.
const float exposure_bias = 1.8f;
const float A = 0.0245786f;
const float B = 0.000090537f;
@ -138,46 +141,46 @@ vec3 tonemap_aces(vec3 color, float white) {
vec3 color_tonemapped = (color * (color + A) - B) / (color * (C * color + D) + E);
color_tonemapped *= odt_to_rgb;
white *= exposure_bias;
float white_tonemapped = (white * (white + A) - B) / (white * (C * white + D) + E);
return color_tonemapped / white_tonemapped;
return color_tonemapped / params.tonemapper_params.x;
}
// Polynomial approximation of EaryChow's AgX sigmoid curve.
// x must be within the range [0.0, 1.0]
vec3 agx_contrast_approx(vec3 x) {
// Generated with Excel trendline
// Input data: Generated using python sigmoid with EaryChow's configuration and 57 steps
// Additional padding values were added to give correct intersections at 0.0 and 1.0
// 6th order, intercept of 0.0 to remove an operation and ensure intersection at 0.0
vec3 x2 = x * x;
vec3 x4 = x2 * x2;
return 0.021 * x + 4.0111 * x2 - 25.682 * x2 * x + 70.359 * x4 - 74.778 * x4 * x + 27.069 * x4 * x2;
// allenwp tonemapping curve; developed for use in the Godot game engine.
// Source and details: https://allenwp.com/blog/2025/05/29/allenwp-tonemapping-curve/
// Input must be a non-negative linear scene value.
vec3 allenwp_curve(vec3 x) {
const float output_max_value = 1.0; // SDR always has an output_max_value of 1.0
// These constants must match the those in the C++ code that calculates the parameters.
// 18% "middle gray" is perceptually 50% of the brightness of reference white.
const float awp_crossover_point = 0.18;
// When output_max_value and/or awp_crossover_point are no longer constant,
// awp_shoulder_max can be calculated on the CPU and passed in as params.tonemap_e.
const float awp_shoulder_max = output_max_value - awp_crossover_point;
float awp_contrast = params.tonemapper_params.x;
float awp_toe_a = params.tonemapper_params.y;
float awp_slope = params.tonemapper_params.z;
float awp_w = params.tonemapper_params.w;
// Reinhard-like shoulder:
vec3 s = x - awp_crossover_point;
vec3 slope_s = awp_slope * s;
s = slope_s * (1.0 + s / awp_w) / (1.0 + (slope_s / awp_shoulder_max));
s += awp_crossover_point;
// Sigmoid power function toe:
vec3 t = pow(x, vec3(awp_contrast));
t = t / (t + awp_toe_a);
return mix(s, t, lessThan(x, vec3(awp_crossover_point)));
}
// This is an approximation and simplification of EaryChow's AgX implementation that is used by Blender.
// This code is based off of the script that generates the AgX_Base_sRGB.cube LUT that Blender uses.
// Source: https://github.com/EaryChow/AgX_LUT_Gen/blob/main/AgXBasesRGB.py
// Colorspace transformation source: https://www.colour-science.org:8010/apps/rgb_colourspace_transformation_matrix
vec3 tonemap_agx(vec3 color) {
// Combined linear sRGB to linear Rec 2020 and Blender AgX inset matrices:
const mat3 srgb_to_rec2020_agx_inset_matrix = mat3(
0.54490813676363087053, 0.14044005884001287035, 0.088827411851915368603,
0.37377945959812267119, 0.75410959864013760045, 0.17887712465043811023,
0.081384976686407536266, 0.10543358536857773485, 0.73224999956948382528);
// Combined inverse AgX outset matrix and linear Rec 2020 to linear sRGB matrices.
const mat3 agx_outset_rec2020_to_srgb_matrix = mat3(
1.9645509602733325934, -0.29932243390911083839, -0.16436833806080403409,
-0.85585845117807513559, 1.3264510741502356555, -0.23822464068860595117,
-0.10886710826831608324, -0.027084020983874825605, 1.402665347143271889);
// LOG2_MIN = -10.0
// LOG2_MAX = +6.5
// MIDDLE_GRAY = 0.18
const float min_ev = -12.4739311883324; // log2(pow(2, LOG2_MIN) * MIDDLE_GRAY)
const float max_ev = 4.02606881166759; // log2(pow(2, LOG2_MAX) * MIDDLE_GRAY)
// Input color should be non-negative!
// Large negative values in one channel and large positive values in other
// channels can result in a colour that appears darker and more saturated than
// desired after passing it through the inset matrix. For this reason, it is
@ -185,31 +188,43 @@ vec3 tonemap_agx(vec3 color) {
// This is done before the Rec. 2020 transform to allow the Rec. 2020
// transform to be combined with the AgX inset matrix. This results in a loss
// of color information that could be correctly interpreted within the
// Rec. 2020 color space as positive RGB values, but it is less common for Godot
// to provide this function with negative sRGB values and therefore not worth
// Rec. 2020 color space as positive RGB values, but is often not worth
// the performance cost of an additional matrix multiplication.
// A value of 2e-10 intentionally introduces insignificant error to prevent
// log2(0.0) after the inset matrix is applied; color will be >= 1e-10 after
// the matrix transform.
color = max(color, 2e-10);
//
// Additionally, this AgX configuration was created subjectively based on
// output appearance in the Rec. 709 color gamut, so it is possible that these
// matrices will not perform well with non-Rec. 709 output (more testing with
// future wide-gamut displays is be needed).
// See this comment from the author on the decisions made to create the matrices:
// https://github.com/godotengine/godot-proposals/issues/12317#issuecomment-2835824250
// Do AGX in rec2020 to match Blender and then apply inset matrix.
color = srgb_to_rec2020_agx_inset_matrix * color;
// Combined Rec. 709 to Rec. 2020 and Blender AgX inset matrices:
const mat3 rec709_to_rec2020_agx_inset_matrix = mat3(
0.544814746488245, 0.140416948464053, 0.0888104196149096,
0.373787398372697, 0.754137554567394, 0.178871756420858,
0.0813978551390581, 0.105445496968552, 0.732317823964232);
// Log2 space encoding.
// Must be clamped because agx_contrast_approx may not work
// well with values outside of the range [0.0, 1.0]
color = clamp(log2(color), min_ev, max_ev);
color = (color - min_ev) / (max_ev - min_ev);
// Combined inverse AgX outset matrix and Rec. 2020 to Rec. 709 matrices.
const mat3 agx_outset_rec2020_to_rec709_matrix = mat3(
1.96488741169489, -0.299313364904742, -0.164352742528393,
-0.855988495690215, 1.32639796461980, -0.238183969428088,
-0.108898916004672, -0.0270845997150571, 1.40253671195648);
// Apply sigmoid function approximation.
color = agx_contrast_approx(color);
const float output_max_value = 1.0; // SDR always has an output_max_value of 1.0
// Convert back to linear before applying outset matrix.
color = pow(color, vec3(2.4));
// Apply inset matrix.
color = rec709_to_rec2020_agx_inset_matrix * color;
// Apply outset to make the result more chroma-laden and then go back to linear sRGB.
color = agx_outset_rec2020_to_srgb_matrix * color;
// Use the allenwp tonemapping curve to match the Blender AgX curve while
// providing stability across all variable dyanimc range (SDR, HDR, EDR).
color = allenwp_curve(color);
// Clipping to output_max_value is required to address a cyan colour that occurs
// with very bright inputs.
color = min(vec3(output_max_value), color);
// Apply outset to make the result more chroma-laden and then go back to Rec. 709.
color = agx_outset_rec2020_to_rec709_matrix * color;
// Blender's lusRGB.compensate_low_side is too complex for this shader, so
// simply return the color, even if it has negative components. These negative
@ -233,17 +248,21 @@ vec3 srgb_to_linear(vec3 color) {
#define TONEMAPPER_ACES 3
#define TONEMAPPER_AGX 4
vec3 apply_tonemapping(vec3 color, float white) { // inputs are LINEAR
// Ensure color values passed to tonemappers are positive.
// They can be negative in the case of negative lights, which leads to undesired behavior.
vec3 apply_tonemapping(vec3 color) { // inputs are LINEAR
if (params.tonemapper == TONEMAPPER_LINEAR) {
return color;
} else if (params.tonemapper == TONEMAPPER_REINHARD) {
return tonemap_reinhard(max(vec3(0.0f), color), white);
}
// Ensure color values passed to tonemappers are positive.
// They can be negative in the case of negative lights, which leads to undesired behavior.
color = max(vec3(0.0), color);
if (params.tonemapper == TONEMAPPER_REINHARD) {
return tonemap_reinhard(color);
} else if (params.tonemapper == TONEMAPPER_FILMIC) {
return tonemap_filmic(max(vec3(0.0f), color), white);
return tonemap_filmic(color);
} else if (params.tonemapper == TONEMAPPER_ACES) {
return tonemap_aces(max(vec3(0.0f), color), white);
return tonemap_aces(color);
} else { // TONEMAPPER_AGX
return tonemap_agx(color);
}
@ -876,7 +895,7 @@ void main() {
// Tonemap to lower dynamic range.
color.rgb = apply_tonemapping(color.rgb, params.white);
color.rgb = apply_tonemapping(color.rgb);
// Post-tonemap glow.
@ -888,7 +907,7 @@ void main() {
if (params.glow_map_strength > 0.001) {
glow = mix(glow, texture(glow_map, uv_interp).rgb * glow, params.glow_map_strength);
}
glow = apply_tonemapping(glow, params.white);
glow = apply_tonemapping(glow);
color.rgb = apply_glow(color.rgb, glow, params.white);
}

157
servers/rendering/renderer_rd/shaders/effects/tonemap_mobile.glsl
View file

@ -89,23 +89,26 @@ layout(push_constant, std430) uniform Params {
float glow_map_strength;
float exposure;
float white;
vec4 tonemapper_params;
}
params;
layout(location = 0) out vec4 frag_color;
// Based on Reinhard's extended formula, see equation 4 in https://doi.org/cjbgrt
vec3 tonemap_reinhard(vec3 color, float white) {
float white_squared = white * white;
vec3 tonemap_reinhard(vec3 color) {
float white_squared = params.tonemapper_params.x;
vec3 white_squared_color = white_squared * color;
// Equivalent to color * (1 + color / white_squared) / (1 + color)
return (white_squared_color + color * color) / (white_squared_color + white_squared);
}
vec3 tonemap_filmic(vec3 color, float white) {
// exposure bias: input scale (color *= bias, white *= bias) to make the brightness consistent with other tonemappers
// also useful to scale the input to the range that the tonemapper is designed for (some require very high input values)
// has no effect on the curve's general shape or visual properties
vec3 tonemap_filmic(vec3 color) {
// These constants must match the those in the C++ code that calculates the parameters.
// exposure_bias: Input scale (color *= bias, env->white *= bias) to make the brightness consistent with other tonemappers.
// Also useful to scale the input to the range that the tonemapper is designed for (some require very high input values).
// Has no effect on the curve's general shape or visual properties.
const float exposure_bias = 2.0f;
const float A = 0.22f * exposure_bias * exposure_bias; // bias baked into constants for performance
const float B = 0.30f * exposure_bias;
@ -115,14 +118,14 @@ vec3 tonemap_filmic(vec3 color, float white) {
const float F = 0.30f;
vec3 color_tonemapped = ((color * (A * color + C * B) + D * E) / (color * (A * color + B) + D * F)) - E / F;
float white_tonemapped = ((white * (A * white + C * B) + D * E) / (white * (A * white + B) + D * F)) - E / F;
return color_tonemapped / white_tonemapped;
return color_tonemapped / params.tonemapper_params.x;
}
// Adapted from https://github.com/TheRealMJP/BakingLab/blob/master/BakingLab/ACES.hlsl
// (MIT License).
vec3 tonemap_aces(vec3 color, float white) {
vec3 tonemap_aces(vec3 color) {
// These constants must match the those in the C++ code that calculates the parameters.
const float exposure_bias = 1.8f;
const float A = 0.0245786f;
const float B = 0.000090537f;
@ -145,46 +148,46 @@ vec3 tonemap_aces(vec3 color, float white) {
vec3 color_tonemapped = (color * (color + A) - B) / (color * (C * color + D) + E);
color_tonemapped *= odt_to_rgb;
white *= exposure_bias;
float white_tonemapped = (white * (white + A) - B) / (white * (C * white + D) + E);
return color_tonemapped / white_tonemapped;
return color_tonemapped / params.tonemapper_params.x;
}
// Polynomial approximation of EaryChow's AgX sigmoid curve.
// x must be within the range [0.0, 1.0]
vec3 agx_contrast_approx(vec3 x) {
// Generated with Excel trendline
// Input data: Generated using python sigmoid with EaryChow's configuration and 57 steps
// Additional padding values were added to give correct intersections at 0.0 and 1.0
// 6th order, intercept of 0.0 to remove an operation and ensure intersection at 0.0
vec3 x2 = x * x;
vec3 x4 = x2 * x2;
return 0.021 * x + 4.0111 * x2 - 25.682 * x2 * x + 70.359 * x4 - 74.778 * x4 * x + 27.069 * x4 * x2;
// allenwp tonemapping curve; developed for use in the Godot game engine.
// Source and details: https://allenwp.com/blog/2025/05/29/allenwp-tonemapping-curve/
// Input must be a non-negative linear scene value.
vec3 allenwp_curve(vec3 x) {
const float output_max_value = 1.0; // SDR always has an output_max_value of 1.0
// These constants must match the those in the C++ code that calculates the parameters.
// 18% "middle gray" is perceptually 50% of the brightness of reference white.
const float awp_crossover_point = 0.18;
// When output_max_value and/or awp_crossover_point are no longer constant,
// awp_shoulder_max can be calculated on the CPU and passed in as params.tonemap_e.
const float awp_shoulder_max = output_max_value - awp_crossover_point;
float awp_contrast = params.tonemapper_params.x;
float awp_toe_a = params.tonemapper_params.y;
float awp_slope = params.tonemapper_params.z;
float awp_w = params.tonemapper_params.w;
// Reinhard-like shoulder:
vec3 s = x - awp_crossover_point;
vec3 slope_s = awp_slope * s;
s = slope_s * (1.0 + s / awp_w) / (1.0 + (slope_s / awp_shoulder_max));
s += awp_crossover_point;
// Sigmoid power function toe:
vec3 t = pow(x, vec3(awp_contrast));
t = t / (t + awp_toe_a);
return mix(s, t, lessThan(x, vec3(awp_crossover_point)));
}
// This is an approximation and simplification of EaryChow's AgX implementation that is used by Blender.
// This code is based off of the script that generates the AgX_Base_sRGB.cube LUT that Blender uses.
// Source: https://github.com/EaryChow/AgX_LUT_Gen/blob/main/AgXBasesRGB.py
// Colorspace transformation source: https://www.colour-science.org:8010/apps/rgb_colourspace_transformation_matrix
vec3 tonemap_agx(vec3 color) {
// Combined linear sRGB to linear Rec 2020 and Blender AgX inset matrices:
const mat3 srgb_to_rec2020_agx_inset_matrix = mat3(
0.54490813676363087053, 0.14044005884001287035, 0.088827411851915368603,
0.37377945959812267119, 0.75410959864013760045, 0.17887712465043811023,
0.081384976686407536266, 0.10543358536857773485, 0.73224999956948382528);
// Combined inverse AgX outset matrix and linear Rec 2020 to linear sRGB matrices.
const mat3 agx_outset_rec2020_to_srgb_matrix = mat3(
1.9645509602733325934, -0.29932243390911083839, -0.16436833806080403409,
-0.85585845117807513559, 1.3264510741502356555, -0.23822464068860595117,
-0.10886710826831608324, -0.027084020983874825605, 1.402665347143271889);
// LOG2_MIN = -10.0
// LOG2_MAX = +6.5
// MIDDLE_GRAY = 0.18
const float min_ev = -12.4739311883324; // log2(pow(2, LOG2_MIN) * MIDDLE_GRAY)
const float max_ev = 4.02606881166759; // log2(pow(2, LOG2_MAX) * MIDDLE_GRAY)
// Input color should be non-negative!
// Large negative values in one channel and large positive values in other
// channels can result in a colour that appears darker and more saturated than
// desired after passing it through the inset matrix. For this reason, it is
@ -192,31 +195,43 @@ vec3 tonemap_agx(vec3 color) {
// This is done before the Rec. 2020 transform to allow the Rec. 2020
// transform to be combined with the AgX inset matrix. This results in a loss
// of color information that could be correctly interpreted within the
// Rec. 2020 color space as positive RGB values, but it is less common for Godot
// to provide this function with negative sRGB values and therefore not worth
// Rec. 2020 color space as positive RGB values, but is often not worth
// the performance cost of an additional matrix multiplication.
// A value of 2e-10 intentionally introduces insignificant error to prevent
// log2(0.0) after the inset matrix is applied; color will be >= 1e-10 after
// the matrix transform.
color = max(color, 2e-10);
//
// Additionally, this AgX configuration was created subjectively based on
// output appearance in the Rec. 709 color gamut, so it is possible that these
// matrices will not perform well with non-Rec. 709 output (more testing with
// future wide-gamut displays is be needed).
// See this comment from the author on the decisions made to create the matrices:
// https://github.com/godotengine/godot-proposals/issues/12317#issuecomment-2835824250
// Do AGX in rec2020 to match Blender and then apply inset matrix.
color = srgb_to_rec2020_agx_inset_matrix * color;
// Combined Rec. 709 to Rec. 2020 and Blender AgX inset matrices:
const mat3 rec709_to_rec2020_agx_inset_matrix = mat3(
0.544814746488245, 0.140416948464053, 0.0888104196149096,
0.373787398372697, 0.754137554567394, 0.178871756420858,
0.0813978551390581, 0.105445496968552, 0.732317823964232);
// Log2 space encoding.
// Must be clamped because agx_contrast_approx may not work
// well with values outside of the range [0.0, 1.0]
color = clamp(log2(color), min_ev, max_ev);
color = (color - min_ev) / (max_ev - min_ev);
// Combined inverse AgX outset matrix and Rec. 2020 to Rec. 709 matrices.
const mat3 agx_outset_rec2020_to_rec709_matrix = mat3(
1.96488741169489, -0.299313364904742, -0.164352742528393,
-0.855988495690215, 1.32639796461980, -0.238183969428088,
-0.108898916004672, -0.0270845997150571, 1.40253671195648);
// Apply sigmoid function approximation.
color = agx_contrast_approx(color);
const float output_max_value = 1.0; // SDR always has an output_max_value of 1.0
// Convert back to linear before applying outset matrix.
color = pow(color, vec3(2.4));
// Apply inset matrix.
color = rec709_to_rec2020_agx_inset_matrix * color;
// Apply outset to make the result more chroma-laden and then go back to linear sRGB.
color = agx_outset_rec2020_to_srgb_matrix * color;
// Use the allenwp tonemapping curve to match the Blender AgX curve while
// providing stability across all variable dyanimc range (SDR, HDR, EDR).
color = allenwp_curve(color);
// Clipping to output_max_value is required to address a cyan colour that occurs
// with very bright inputs.
color = min(vec3(output_max_value), color);
// Apply outset to make the result more chroma-laden and then go back to Rec. 709.
color = agx_outset_rec2020_to_rec709_matrix * color;
// Blender's lusRGB.compensate_low_side is too complex for this shader, so
// simply return the color, even if it has negative components. These negative
@ -234,17 +249,21 @@ vec3 srgb_to_linear(vec3 color) {
return mix(pow((color.rgb + a) * (1.0f / (vec3(1.0f) + a)), vec3(2.4f)), color.rgb * (1.0f / 12.92f), lessThan(color.rgb, vec3(0.04045f)));
}
vec3 apply_tonemapping(vec3 color, float white) { // inputs are LINEAR
// Ensure color values passed to tonemappers are positive.
// They can be negative in the case of negative lights, which leads to undesired behavior.
vec3 apply_tonemapping(vec3 color) { // inputs are LINEAR
if (tonemapper_linear) {
return color;
} else if (tonemapper_reinhard) {
return tonemap_reinhard(max(vec3(0.0f), color), white);
}
// Ensure color values passed to tonemappers are positive.
// They can be negative in the case of negative lights, which leads to undesired behavior.
color = max(vec3(0.0), color);
if (tonemapper_reinhard) {
return tonemap_reinhard(color);
} else if (tonemapper_filmic) {
return tonemap_filmic(max(vec3(0.0f), color), white);
return tonemap_filmic(color);
} else if (tonemapper_aces) {
return tonemap_aces(max(vec3(0.0f), color), white);
return tonemap_aces(color);
} else { // tonemapper_agx
return tonemap_agx(color);
}
@ -748,7 +767,7 @@ void main() {
// Tonemap to lower dynamic range.
color.rgb = apply_tonemapping(color.rgb, params.white);
color.rgb = apply_tonemapping(color.rgb);
#ifndef SUBPASS
// Post-tonemap glow.
@ -761,7 +780,7 @@ void main() {
if (use_glow_map) {
glow = mix(glow, texture(glow_map, uv_interp).rgb * glow, params.glow_map_strength);
}
glow = apply_tonemapping(glow, params.white);
glow = apply_tonemapping(glow);
color.rgb = apply_glow(color.rgb, glow, params.white);
}
#endif