godot/servers/rendering/renderer_rd/shaders/effects/tonemap.glsl

#[vertex]

#version 450

#VERSION_DEFINES

layout(location = 0) out vec2 uv_interp;

void main() {
	// old code, ARM driver bug on Mali-GXXx GPUs and Vulkan API 1.3.xxx
	// https://github.com/godotengine/godot/pull/92817#issuecomment-2168625982
	//vec2 base_arr[3] = vec2[](vec2(-1.0, -1.0), vec2(-1.0, 3.0), vec2(3.0, -1.0));
	//gl_Position = vec4(base_arr[gl_VertexIndex], 0.0, 1.0);
	//uv_interp = clamp(gl_Position.xy, vec2(0.0, 0.0), vec2(1.0, 1.0)) * 2.0; // saturate(x) * 2.0

	vec2 vertex_base;
	if (gl_VertexIndex == 0) {
		vertex_base = vec2(-1.0, -1.0);
	} else if (gl_VertexIndex == 1) {
		vertex_base = vec2(-1.0, 3.0);
	} else {
		vertex_base = vec2(3.0, -1.0);
	}
	gl_Position = vec4(vertex_base, 0.0, 1.0);
	uv_interp = clamp(vertex_base, vec2(0.0, 0.0), vec2(1.0, 1.0)) * 2.0; // saturate(x) * 2.0
}

#[fragment]

#version 450

#VERSION_DEFINES

#ifdef USE_MULTIVIEW
#extension GL_EXT_multiview : enable
#define ViewIndex gl_ViewIndex
#endif //USE_MULTIVIEW

layout(location = 0) in vec2 uv_interp;

#ifdef SUBPASS
layout(input_attachment_index = 0, set = 0, binding = 0) uniform subpassInput input_color;
#elif defined(USE_MULTIVIEW)
layout(set = 0, binding = 0) uniform sampler2DArray source_color;
#else
layout(set = 0, binding = 0) uniform sampler2D source_color;
#endif

layout(set = 1, binding = 0) uniform sampler2D source_auto_exposure;
#ifdef USE_MULTIVIEW
layout(set = 2, binding = 0) uniform sampler2DArray source_glow;
#else
layout(set = 2, binding = 0) uniform sampler2D source_glow;
#endif
layout(set = 2, binding = 1) uniform sampler2D glow_map;

#ifdef USE_1D_LUT
layout(set = 3, binding = 0) uniform sampler2D source_color_correction;
#else
layout(set = 3, binding = 0) uniform sampler3D source_color_correction;
#endif

#define FLAG_USE_BCS (1 << 0)
#define FLAG_USE_GLOW (1 << 1)
#define FLAG_USE_AUTO_EXPOSURE (1 << 2)
#define FLAG_USE_COLOR_CORRECTION (1 << 3)
#define FLAG_USE_FXAA (1 << 4)
#define FLAG_USE_8_BIT_DEBANDING (1 << 5)
#define FLAG_USE_10_BIT_DEBANDING (1 << 6)
#define FLAG_CONVERT_TO_SRGB (1 << 7)

layout(push_constant, std430) uniform Params {
	vec3 bcs;
	uint flags;

	vec2 pixel_size;
	uint tonemapper;
	uint pad;

	uvec2 glow_texture_size;
	float glow_intensity;
	float glow_map_strength;

	uint glow_mode;
	float glow_levels[7];

	float exposure;
	float white;
	float auto_exposure_scale;
	float luminance_multiplier;
}
params;

layout(location = 0) out vec4 frag_color;

#ifdef USE_GLOW_FILTER_BICUBIC
// w0, w1, w2, and w3 are the four cubic B-spline basis functions
float w0(float a) {
	return (1.0f / 6.0f) * (a * (a * (-a + 3.0f) - 3.0f) + 1.0f);
}

float w1(float a) {
	return (1.0f / 6.0f) * (a * a * (3.0f * a - 6.0f) + 4.0f);
}

float w2(float a) {
	return (1.0f / 6.0f) * (a * (a * (-3.0f * a + 3.0f) + 3.0f) + 1.0f);
}

float w3(float a) {
	return (1.0f / 6.0f) * (a * a * a);
}

// g0 and g1 are the two amplitude functions
float g0(float a) {
	return w0(a) + w1(a);
}

float g1(float a) {
	return w2(a) + w3(a);
}

// h0 and h1 are the two offset functions
float h0(float a) {
	return -1.0f + w1(a) / (w0(a) + w1(a));
}

float h1(float a) {
	return 1.0f + w3(a) / (w2(a) + w3(a));
}

#ifdef USE_MULTIVIEW
vec4 texture2D_bicubic(sampler2DArray tex, vec2 uv, int p_lod) {
	float lod = float(p_lod);
	vec2 tex_size = vec2(params.glow_texture_size >> p_lod);
	vec2 pixel_size = vec2(1.0f) / tex_size;

	uv = uv * tex_size + vec2(0.5f);

	vec2 iuv = floor(uv);
	vec2 fuv = fract(uv);

	float g0x = g0(fuv.x);
	float g1x = g1(fuv.x);
	float h0x = h0(fuv.x);
	float h1x = h1(fuv.x);
	float h0y = h0(fuv.y);
	float h1y = h1(fuv.y);

	vec3 p0 = vec3((vec2(iuv.x + h0x, iuv.y + h0y) - vec2(0.5f)) * pixel_size, ViewIndex);
	vec3 p1 = vec3((vec2(iuv.x + h1x, iuv.y + h0y) - vec2(0.5f)) * pixel_size, ViewIndex);
	vec3 p2 = vec3((vec2(iuv.x + h0x, iuv.y + h1y) - vec2(0.5f)) * pixel_size, ViewIndex);
	vec3 p3 = vec3((vec2(iuv.x + h1x, iuv.y + h1y) - vec2(0.5f)) * pixel_size, ViewIndex);

	return (g0(fuv.y) * (g0x * textureLod(tex, p0, lod) + g1x * textureLod(tex, p1, lod))) +
			(g1(fuv.y) * (g0x * textureLod(tex, p2, lod) + g1x * textureLod(tex, p3, lod)));
}

#define GLOW_TEXTURE_SAMPLE(m_tex, m_uv, m_lod) texture2D_bicubic(m_tex, m_uv, m_lod)
#else // USE_MULTIVIEW

vec4 texture2D_bicubic(sampler2D tex, vec2 uv, int p_lod) {
	float lod = float(p_lod);
	vec2 tex_size = vec2(params.glow_texture_size >> p_lod);
	vec2 pixel_size = vec2(1.0f) / tex_size;

	uv = uv * tex_size + vec2(0.5f);

	vec2 iuv = floor(uv);
	vec2 fuv = fract(uv);

	float g0x = g0(fuv.x);
	float g1x = g1(fuv.x);
	float h0x = h0(fuv.x);
	float h1x = h1(fuv.x);
	float h0y = h0(fuv.y);
	float h1y = h1(fuv.y);

	vec2 p0 = (vec2(iuv.x + h0x, iuv.y + h0y) - vec2(0.5f)) * pixel_size;
	vec2 p1 = (vec2(iuv.x + h1x, iuv.y + h0y) - vec2(0.5f)) * pixel_size;
	vec2 p2 = (vec2(iuv.x + h0x, iuv.y + h1y) - vec2(0.5f)) * pixel_size;
	vec2 p3 = (vec2(iuv.x + h1x, iuv.y + h1y) - vec2(0.5f)) * pixel_size;

	return (g0(fuv.y) * (g0x * textureLod(tex, p0, lod) + g1x * textureLod(tex, p1, lod))) +
			(g1(fuv.y) * (g0x * textureLod(tex, p2, lod) + g1x * textureLod(tex, p3, lod)));
}

#define GLOW_TEXTURE_SAMPLE(m_tex, m_uv, m_lod) texture2D_bicubic(m_tex, m_uv, m_lod)
#endif // !USE_MULTIVIEW

#else // USE_GLOW_FILTER_BICUBIC

#ifdef USE_MULTIVIEW
#define GLOW_TEXTURE_SAMPLE(m_tex, m_uv, m_lod) textureLod(m_tex, vec3(m_uv, ViewIndex), float(m_lod))
#else // USE_MULTIVIEW
#define GLOW_TEXTURE_SAMPLE(m_tex, m_uv, m_lod) textureLod(m_tex, m_uv, float(m_lod))
#endif // !USE_MULTIVIEW

#endif // !USE_GLOW_FILTER_BICUBIC

// 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 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
	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;
	const float C = 0.10f;
	const float D = 0.20f;
	const float E = 0.01f;
	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;
}

// Adapted from https://github.com/TheRealMJP/BakingLab/blob/master/BakingLab/ACES.hlsl
// (MIT License).
vec3 tonemap_aces(vec3 color, float white) {
	const float exposure_bias = 1.8f;
	const float A = 0.0245786f;
	const float B = 0.000090537f;
	const float C = 0.983729f;
	const float D = 0.432951f;
	const float E = 0.238081f;

	// Exposure bias baked into transform to save shader instructions. Equivalent to `color *= exposure_bias`
	const mat3 rgb_to_rrt = mat3(
			vec3(0.59719f * exposure_bias, 0.35458f * exposure_bias, 0.04823f * exposure_bias),
			vec3(0.07600f * exposure_bias, 0.90834f * exposure_bias, 0.01566f * exposure_bias),
			vec3(0.02840f * exposure_bias, 0.13383f * exposure_bias, 0.83777f * exposure_bias));

	const mat3 odt_to_rgb = mat3(
			vec3(1.60475f, -0.53108f, -0.07367f),
			vec3(-0.10208f, 1.10813f, -0.00605f),
			vec3(-0.00327f, -0.07276f, 1.07602f));

	color *= rgb_to_rrt;
	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;
}

// 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;
}

// 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
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)

	// 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
	// best to prevent negative input values.
	// 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
	// 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);

	// Do AGX in rec2020 to match Blender and then apply inset matrix.
	color = srgb_to_rec2020_agx_inset_matrix * color;

	// 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);

	// Apply sigmoid function approximation.
	color = agx_contrast_approx(color);

	// Convert back to linear before applying outset matrix.
	color = pow(color, vec3(2.4));

	// Apply outset to make the result more chroma-laden and then go back to linear sRGB.
	color = agx_outset_rec2020_to_srgb_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
	// components may be useful for subsequent color adjustments.
	return color;
}

vec3 linear_to_srgb(vec3 color) {
	// Clamping is not strictly necessary for floating point nonlinear sRGB encoding,
	// but many cases that call this function need the result clamped.
	color = clamp(color, vec3(0.0), vec3(1.0));
	const vec3 a = vec3(0.055f);
	return mix((vec3(1.0f) + a) * pow(color.rgb, vec3(1.0f / 2.4f)) - a, 12.92f * color.rgb, lessThan(color.rgb, vec3(0.0031308f)));
}

#define TONEMAPPER_LINEAR 0
#define TONEMAPPER_REINHARD 1
#define TONEMAPPER_FILMIC 2
#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.
	if (params.tonemapper == TONEMAPPER_LINEAR) {
		return color;
	} else if (params.tonemapper == TONEMAPPER_REINHARD) {
		return tonemap_reinhard(max(vec3(0.0f), color), white);
	} else if (params.tonemapper == TONEMAPPER_FILMIC) {
		return tonemap_filmic(max(vec3(0.0f), color), white);
	} else if (params.tonemapper == TONEMAPPER_ACES) {
		return tonemap_aces(max(vec3(0.0f), color), white);
	} else { // TONEMAPPER_AGX
		return tonemap_agx(color);
	}
}

#ifdef USE_MULTIVIEW
vec3 gather_glow(sampler2DArray tex, vec2 uv) { // sample all selected glow levels, view is added to uv later
#else
vec3 gather_glow(sampler2D tex, vec2 uv) { // sample all selected glow levels
#endif // defined(USE_MULTIVIEW)
	vec3 glow = vec3(0.0f);

	if (params.glow_levels[0] > 0.0001) {
		glow += GLOW_TEXTURE_SAMPLE(tex, uv, 0).rgb * params.glow_levels[0];
	}

	if (params.glow_levels[1] > 0.0001) {
		glow += GLOW_TEXTURE_SAMPLE(tex, uv, 1).rgb * params.glow_levels[1];
	}

	if (params.glow_levels[2] > 0.0001) {
		glow += GLOW_TEXTURE_SAMPLE(tex, uv, 2).rgb * params.glow_levels[2];
	}

	if (params.glow_levels[3] > 0.0001) {
		glow += GLOW_TEXTURE_SAMPLE(tex, uv, 3).rgb * params.glow_levels[3];
	}

	if (params.glow_levels[4] > 0.0001) {
		glow += GLOW_TEXTURE_SAMPLE(tex, uv, 4).rgb * params.glow_levels[4];
	}

	if (params.glow_levels[5] > 0.0001) {
		glow += GLOW_TEXTURE_SAMPLE(tex, uv, 5).rgb * params.glow_levels[5];
	}

	if (params.glow_levels[6] > 0.0001) {
		glow += GLOW_TEXTURE_SAMPLE(tex, uv, 6).rgb * params.glow_levels[6];
	}

	return glow;
}

#define GLOW_MODE_ADD 0
#define GLOW_MODE_SCREEN 1
#define GLOW_MODE_SOFTLIGHT 2
#define GLOW_MODE_REPLACE 3
#define GLOW_MODE_MIX 4

vec3 apply_glow(vec3 color, vec3 glow) { // apply glow using the selected blending mode
	if (params.glow_mode == GLOW_MODE_ADD) {
		return color + glow;
	} else if (params.glow_mode == GLOW_MODE_SCREEN) {
		// Needs color clamping.
		glow.rgb = clamp(glow.rgb, vec3(0.0f), vec3(1.0f));
		return max((color + glow) - (color * glow), vec3(0.0));
	} else if (params.glow_mode == GLOW_MODE_SOFTLIGHT) {
		// Needs color clamping.
		glow.rgb = clamp(glow.rgb, vec3(0.0f), vec3(1.0f));
		glow = glow * vec3(0.5f) + vec3(0.5f);

		color.r = (glow.r <= 0.5f) ? (color.r - (1.0f - 2.0f * glow.r) * color.r * (1.0f - color.r)) : (((glow.r > 0.5f) && (color.r <= 0.25f)) ? (color.r + (2.0f * glow.r - 1.0f) * (4.0f * color.r * (4.0f * color.r + 1.0f) * (color.r - 1.0f) + 7.0f * color.r)) : (color.r + (2.0f * glow.r - 1.0f) * (sqrt(color.r) - color.r)));
		color.g = (glow.g <= 0.5f) ? (color.g - (1.0f - 2.0f * glow.g) * color.g * (1.0f - color.g)) : (((glow.g > 0.5f) && (color.g <= 0.25f)) ? (color.g + (2.0f * glow.g - 1.0f) * (4.0f * color.g * (4.0f * color.g + 1.0f) * (color.g - 1.0f) + 7.0f * color.g)) : (color.g + (2.0f * glow.g - 1.0f) * (sqrt(color.g) - color.g)));
		color.b = (glow.b <= 0.5f) ? (color.b - (1.0f - 2.0f * glow.b) * color.b * (1.0f - color.b)) : (((glow.b > 0.5f) && (color.b <= 0.25f)) ? (color.b + (2.0f * glow.b - 1.0f) * (4.0f * color.b * (4.0f * color.b + 1.0f) * (color.b - 1.0f) + 7.0f * color.b)) : (color.b + (2.0f * glow.b - 1.0f) * (sqrt(color.b) - color.b)));
		return color;
	} else { //replace
		return glow;
	}
}

vec3 apply_bcs(vec3 color, vec3 bcs) {
	color = mix(vec3(0.0f), color, bcs.x);
	color = mix(vec3(0.5f), color, bcs.y);
	color = mix(vec3(dot(vec3(1.0f), color) * 0.33333f), color, bcs.z);

	return color;
}
#ifdef USE_1D_LUT
vec3 apply_color_correction(vec3 color) {
	color.r = texture(source_color_correction, vec2(color.r, 0.0f)).r;
	color.g = texture(source_color_correction, vec2(color.g, 0.0f)).g;
	color.b = texture(source_color_correction, vec2(color.b, 0.0f)).b;
	return color;
}
#else
vec3 apply_color_correction(vec3 color) {
	return textureLod(source_color_correction, color, 0.0).rgb;
}
#endif

#ifndef SUBPASS

// FXAA 3.11 compact, Ported from https://github.com/kosua20/Rendu/blob/master/resources/common/shaders/screens/fxaa.frag
///////////////////////////////////////////////////////////////////////////////////
// MIT License
//
// Copyright (c) 2017 Simon Rodriguez
//
// 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.
///////////////////////////////////////////////////////////////////////////////////

// Nvidia Original FXAA 3.11 License
//----------------------------------------------------------------------------------
// File:        es3-kepler\FXAA/FXAA3_11.h
// SDK Version: v3.00
// Email:       gameworks@nvidia.com
// Site:        http://developer.nvidia.com/
//
// Copyright (c) 2014-2015, NVIDIA CORPORATION. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//  * Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//  * Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//  * Neither the name of NVIDIA CORPORATION nor the names of its
//    contributors may be used to endorse or promote products derived
//    from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
//----------------------------------------------------------------------------------
//
//                    NVIDIA FXAA 3.11 by TIMOTHY LOTTES
//
//----------------------------------------------------------------------------------

float QUALITY(float q) {
	return (q < 5 ? 1.0 : (q > 5 ? (q < 10 ? 2.0 : (q < 11 ? 4.0 : 8.0)) : 1.5));
}

float rgb2luma(vec3 rgb) {
	return sqrt(dot(rgb, vec3(0.299, 0.587, 0.114)));
}

vec3 do_fxaa(vec3 color, float exposure, vec2 uv_interp) {
	const float EDGE_THRESHOLD_MIN = 0.0312;
	const float EDGE_THRESHOLD_MAX = 0.125;
	const int ITERATIONS = 12;
	const float SUBPIXEL_QUALITY = 0.75;

#ifdef USE_MULTIVIEW
	float lumaUp = rgb2luma(textureLodOffset(source_color, vec3(uv_interp, ViewIndex), 0.0, ivec2(0, 1)).xyz * exposure * params.luminance_multiplier);
	float lumaDown = rgb2luma(textureLodOffset(source_color, vec3(uv_interp, ViewIndex), 0.0, ivec2(0, -1)).xyz * exposure * params.luminance_multiplier);
	float lumaLeft = rgb2luma(textureLodOffset(source_color, vec3(uv_interp, ViewIndex), 0.0, ivec2(-1, 0)).xyz * exposure * params.luminance_multiplier);
	float lumaRight = rgb2luma(textureLodOffset(source_color, vec3(uv_interp, ViewIndex), 0.0, ivec2(1, 0)).xyz * exposure * params.luminance_multiplier);

	float lumaCenter = rgb2luma(color);

	float lumaMin = min(lumaCenter, min(min(lumaUp, lumaDown), min(lumaLeft, lumaRight)));
	float lumaMax = max(lumaCenter, max(max(lumaUp, lumaDown), max(lumaLeft, lumaRight)));

	float lumaRange = lumaMax - lumaMin;

	if (lumaRange < max(EDGE_THRESHOLD_MIN, lumaMax * EDGE_THRESHOLD_MAX)) {
		return color;
	}

	float lumaDownLeft = rgb2luma(textureLodOffset(source_color, vec3(uv_interp, ViewIndex), 0.0, ivec2(-1, -1)).xyz * exposure * params.luminance_multiplier);
	float lumaUpRight = rgb2luma(textureLodOffset(source_color, vec3(uv_interp, ViewIndex), 0.0, ivec2(1, 1)).xyz * exposure * params.luminance_multiplier);
	float lumaUpLeft = rgb2luma(textureLodOffset(source_color, vec3(uv_interp, ViewIndex), 0.0, ivec2(-1, 1)).xyz * exposure * params.luminance_multiplier);
	float lumaDownRight = rgb2luma(textureLodOffset(source_color, vec3(uv_interp, ViewIndex), 0.0, ivec2(1, -1)).xyz * exposure * params.luminance_multiplier);

	float lumaDownUp = lumaDown + lumaUp;
	float lumaLeftRight = lumaLeft + lumaRight;

	float lumaLeftCorners = lumaDownLeft + lumaUpLeft;
	float lumaDownCorners = lumaDownLeft + lumaDownRight;
	float lumaRightCorners = lumaDownRight + lumaUpRight;
	float lumaUpCorners = lumaUpRight + lumaUpLeft;

	float edgeHorizontal = abs(-2.0 * lumaLeft + lumaLeftCorners) + abs(-2.0 * lumaCenter + lumaDownUp) * 2.0 + abs(-2.0 * lumaRight + lumaRightCorners);
	float edgeVertical = abs(-2.0 * lumaUp + lumaUpCorners) + abs(-2.0 * lumaCenter + lumaLeftRight) * 2.0 + abs(-2.0 * lumaDown + lumaDownCorners);

	bool isHorizontal = (edgeHorizontal >= edgeVertical);

	float stepLength = isHorizontal ? params.pixel_size.y : params.pixel_size.x;

	float luma1 = isHorizontal ? lumaDown : lumaLeft;
	float luma2 = isHorizontal ? lumaUp : lumaRight;
	float gradient1 = luma1 - lumaCenter;
	float gradient2 = luma2 - lumaCenter;

	bool is1Steepest = abs(gradient1) >= abs(gradient2);

	float gradientScaled = 0.25 * max(abs(gradient1), abs(gradient2));

	float lumaLocalAverage = 0.0;
	if (is1Steepest) {
		stepLength = -stepLength;
		lumaLocalAverage = 0.5 * (luma1 + lumaCenter);
	} else {
		lumaLocalAverage = 0.5 * (luma2 + lumaCenter);
	}

	vec2 currentUv = uv_interp;
	if (isHorizontal) {
		currentUv.y += stepLength * 0.5;
	} else {
		currentUv.x += stepLength * 0.5;
	}

	vec2 offset = isHorizontal ? vec2(params.pixel_size.x, 0.0) : vec2(0.0, params.pixel_size.y);
	vec3 uv1 = vec3(currentUv - offset * QUALITY(0), ViewIndex);
	vec3 uv2 = vec3(currentUv + offset * QUALITY(0), ViewIndex);

	float lumaEnd1 = rgb2luma(textureLod(source_color, uv1, 0.0).xyz * exposure * params.luminance_multiplier);
	float lumaEnd2 = rgb2luma(textureLod(source_color, uv2, 0.0).xyz * exposure * params.luminance_multiplier);
	lumaEnd1 -= lumaLocalAverage;
	lumaEnd2 -= lumaLocalAverage;

	bool reached1 = abs(lumaEnd1) >= gradientScaled;
	bool reached2 = abs(lumaEnd2) >= gradientScaled;
	bool reachedBoth = reached1 && reached2;

	if (!reached1) {
		uv1 -= vec3(offset * QUALITY(1), 0.0);
	}
	if (!reached2) {
		uv2 += vec3(offset * QUALITY(1), 0.0);
	}

	if (!reachedBoth) {
		for (int i = 2; i < ITERATIONS; i++) {
			if (!reached1) {
				lumaEnd1 = rgb2luma(textureLod(source_color, uv1, 0.0).xyz * exposure * params.luminance_multiplier);
				lumaEnd1 = lumaEnd1 - lumaLocalAverage;
			}
			if (!reached2) {
				lumaEnd2 = rgb2luma(textureLod(source_color, uv2, 0.0).xyz * exposure * params.luminance_multiplier);
				lumaEnd2 = lumaEnd2 - lumaLocalAverage;
			}
			reached1 = abs(lumaEnd1) >= gradientScaled;
			reached2 = abs(lumaEnd2) >= gradientScaled;
			reachedBoth = reached1 && reached2;
			if (!reached1) {
				uv1 -= vec3(offset * QUALITY(i), 0.0);
			}
			if (!reached2) {
				uv2 += vec3(offset * QUALITY(i), 0.0);
			}
			if (reachedBoth) {
				break;
			}
		}
	}

	float distance1 = isHorizontal ? (uv_interp.x - uv1.x) : (uv_interp.y - uv1.y);
	float distance2 = isHorizontal ? (uv2.x - uv_interp.x) : (uv2.y - uv_interp.y);

	bool isDirection1 = distance1 < distance2;
	float distanceFinal = min(distance1, distance2);

	float edgeThickness = (distance1 + distance2);

	bool isLumaCenterSmaller = lumaCenter < lumaLocalAverage;

	bool correctVariation1 = (lumaEnd1 < 0.0) != isLumaCenterSmaller;
	bool correctVariation2 = (lumaEnd2 < 0.0) != isLumaCenterSmaller;

	bool correctVariation = isDirection1 ? correctVariation1 : correctVariation2;

	float pixelOffset = -distanceFinal / edgeThickness + 0.5;

	float finalOffset = correctVariation ? pixelOffset : 0.0;

	float lumaAverage = (1.0 / 12.0) * (2.0 * (lumaDownUp + lumaLeftRight) + lumaLeftCorners + lumaRightCorners);

	float subPixelOffset1 = clamp(abs(lumaAverage - lumaCenter) / lumaRange, 0.0, 1.0);
	float subPixelOffset2 = (-2.0 * subPixelOffset1 + 3.0) * subPixelOffset1 * subPixelOffset1;

	float subPixelOffsetFinal = subPixelOffset2 * subPixelOffset2 * SUBPIXEL_QUALITY;

	finalOffset = max(finalOffset, subPixelOffsetFinal);

	vec3 finalUv = vec3(uv_interp, ViewIndex);
	if (isHorizontal) {
		finalUv.y += finalOffset * stepLength;
	} else {
		finalUv.x += finalOffset * stepLength;
	}

	vec3 finalColor = textureLod(source_color, finalUv, 0.0).xyz * exposure * params.luminance_multiplier;
	return finalColor;

#else
	float lumaUp = rgb2luma(textureLodOffset(source_color, uv_interp, 0.0, ivec2(0, 1)).xyz * exposure * params.luminance_multiplier);
	float lumaDown = rgb2luma(textureLodOffset(source_color, uv_interp, 0.0, ivec2(0, -1)).xyz * exposure * params.luminance_multiplier);
	float lumaLeft = rgb2luma(textureLodOffset(source_color, uv_interp, 0.0, ivec2(-1, 0)).xyz * exposure * params.luminance_multiplier);
	float lumaRight = rgb2luma(textureLodOffset(source_color, uv_interp, 0.0, ivec2(1, 0)).xyz * exposure * params.luminance_multiplier);

	float lumaCenter = rgb2luma(color);

	float lumaMin = min(lumaCenter, min(min(lumaUp, lumaDown), min(lumaLeft, lumaRight)));
	float lumaMax = max(lumaCenter, max(max(lumaUp, lumaDown), max(lumaLeft, lumaRight)));

	float lumaRange = lumaMax - lumaMin;

	if (lumaRange < max(EDGE_THRESHOLD_MIN, lumaMax * EDGE_THRESHOLD_MAX)) {
		return color;
	}

	float lumaDownLeft = rgb2luma(textureLodOffset(source_color, uv_interp, 0.0, ivec2(-1, -1)).xyz * exposure * params.luminance_multiplier);
	float lumaUpRight = rgb2luma(textureLodOffset(source_color, uv_interp, 0.0, ivec2(1, 1)).xyz * exposure * params.luminance_multiplier);
	float lumaUpLeft = rgb2luma(textureLodOffset(source_color, uv_interp, 0.0, ivec2(-1, 1)).xyz * exposure * params.luminance_multiplier);
	float lumaDownRight = rgb2luma(textureLodOffset(source_color, uv_interp, 0.0, ivec2(1, -1)).xyz * exposure * params.luminance_multiplier);

	float lumaDownUp = lumaDown + lumaUp;
	float lumaLeftRight = lumaLeft + lumaRight;

	float lumaLeftCorners = lumaDownLeft + lumaUpLeft;
	float lumaDownCorners = lumaDownLeft + lumaDownRight;
	float lumaRightCorners = lumaDownRight + lumaUpRight;
	float lumaUpCorners = lumaUpRight + lumaUpLeft;

	float edgeHorizontal = abs(-2.0 * lumaLeft + lumaLeftCorners) + abs(-2.0 * lumaCenter + lumaDownUp) * 2.0 + abs(-2.0 * lumaRight + lumaRightCorners);
	float edgeVertical = abs(-2.0 * lumaUp + lumaUpCorners) + abs(-2.0 * lumaCenter + lumaLeftRight) * 2.0 + abs(-2.0 * lumaDown + lumaDownCorners);

	bool isHorizontal = (edgeHorizontal >= edgeVertical);

	float stepLength = isHorizontal ? params.pixel_size.y : params.pixel_size.x;

	float luma1 = isHorizontal ? lumaDown : lumaLeft;
	float luma2 = isHorizontal ? lumaUp : lumaRight;
	float gradient1 = luma1 - lumaCenter;
	float gradient2 = luma2 - lumaCenter;

	bool is1Steepest = abs(gradient1) >= abs(gradient2);

	float gradientScaled = 0.25 * max(abs(gradient1), abs(gradient2));

	float lumaLocalAverage = 0.0;
	if (is1Steepest) {
		stepLength = -stepLength;
		lumaLocalAverage = 0.5 * (luma1 + lumaCenter);
	} else {
		lumaLocalAverage = 0.5 * (luma2 + lumaCenter);
	}

	vec2 currentUv = uv_interp;
	if (isHorizontal) {
		currentUv.y += stepLength * 0.5;
	} else {
		currentUv.x += stepLength * 0.5;
	}

	vec2 offset = isHorizontal ? vec2(params.pixel_size.x, 0.0) : vec2(0.0, params.pixel_size.y);
	vec2 uv1 = currentUv - offset * QUALITY(0);
	vec2 uv2 = currentUv + offset * QUALITY(0);

	float lumaEnd1 = rgb2luma(textureLod(source_color, uv1, 0.0).xyz * exposure * params.luminance_multiplier);
	float lumaEnd2 = rgb2luma(textureLod(source_color, uv2, 0.0).xyz * exposure * params.luminance_multiplier);
	lumaEnd1 -= lumaLocalAverage;
	lumaEnd2 -= lumaLocalAverage;

	bool reached1 = abs(lumaEnd1) >= gradientScaled;
	bool reached2 = abs(lumaEnd2) >= gradientScaled;
	bool reachedBoth = reached1 && reached2;

	if (!reached1) {
		uv1 -= offset * QUALITY(1);
	}
	if (!reached2) {
		uv2 += offset * QUALITY(1);
	}

	if (!reachedBoth) {
		for (int i = 2; i < ITERATIONS; i++) {
			if (!reached1) {
				lumaEnd1 = rgb2luma(textureLod(source_color, uv1, 0.0).xyz * exposure * params.luminance_multiplier);
				lumaEnd1 = lumaEnd1 - lumaLocalAverage;
			}
			if (!reached2) {
				lumaEnd2 = rgb2luma(textureLod(source_color, uv2, 0.0).xyz * exposure * params.luminance_multiplier);
				lumaEnd2 = lumaEnd2 - lumaLocalAverage;
			}
			reached1 = abs(lumaEnd1) >= gradientScaled;
			reached2 = abs(lumaEnd2) >= gradientScaled;
			reachedBoth = reached1 && reached2;
			if (!reached1) {
				uv1 -= offset * QUALITY(i);
			}
			if (!reached2) {
				uv2 += offset * QUALITY(i);
			}
			if (reachedBoth) {
				break;
			}
		}
	}

	float distance1 = isHorizontal ? (uv_interp.x - uv1.x) : (uv_interp.y - uv1.y);
	float distance2 = isHorizontal ? (uv2.x - uv_interp.x) : (uv2.y - uv_interp.y);

	bool isDirection1 = distance1 < distance2;
	float distanceFinal = min(distance1, distance2);

	float edgeThickness = (distance1 + distance2);

	bool isLumaCenterSmaller = lumaCenter < lumaLocalAverage;

	bool correctVariation1 = (lumaEnd1 < 0.0) != isLumaCenterSmaller;
	bool correctVariation2 = (lumaEnd2 < 0.0) != isLumaCenterSmaller;

	bool correctVariation = isDirection1 ? correctVariation1 : correctVariation2;

	float pixelOffset = -distanceFinal / edgeThickness + 0.5;

	float finalOffset = correctVariation ? pixelOffset : 0.0;

	float lumaAverage = (1.0 / 12.0) * (2.0 * (lumaDownUp + lumaLeftRight) + lumaLeftCorners + lumaRightCorners);

	float subPixelOffset1 = clamp(abs(lumaAverage - lumaCenter) / lumaRange, 0.0, 1.0);
	float subPixelOffset2 = (-2.0 * subPixelOffset1 + 3.0) * subPixelOffset1 * subPixelOffset1;

	float subPixelOffsetFinal = subPixelOffset2 * subPixelOffset2 * SUBPIXEL_QUALITY;

	finalOffset = max(finalOffset, subPixelOffsetFinal);

	vec2 finalUv = uv_interp;
	if (isHorizontal) {
		finalUv.y += finalOffset * stepLength;
	} else {
		finalUv.x += finalOffset * stepLength;
	}

	vec3 finalColor = textureLod(source_color, finalUv, 0.0).xyz * exposure * params.luminance_multiplier;
	return finalColor;

#endif
}
#endif // !SUBPASS

// From https://alex.vlachos.com/graphics/Alex_Vlachos_Advanced_VR_Rendering_GDC2015.pdf
// and https://www.shadertoy.com/view/MslGR8 (5th one starting from the bottom)
// NOTE: `frag_coord` is in pixels (i.e. not normalized UV).
// This dithering must be applied after encoding changes (linear/nonlinear) have been applied
// as the final step before quantization from floating point to integer values.
vec3 screen_space_dither(vec2 frag_coord, float bit_alignment_diviser) {
	// Iestyn's RGB dither (7 asm instructions) from Portal 2 X360, slightly modified for VR.
	// Removed the time component to avoid passing time into this shader.
	vec3 dither = vec3(dot(vec2(171.0, 231.0), frag_coord));
	dither.rgb = fract(dither.rgb / vec3(103.0, 71.0, 97.0));

	// Subtract 0.5 to avoid slightly brightening the whole viewport.
	// Use a dither strength of 100% rather than the 37.5% suggested by the original source.
	return (dither.rgb - 0.5) / bit_alignment_diviser;
}

void main() {
#ifdef SUBPASS
	// SUBPASS and USE_MULTIVIEW can be combined but in that case we're already reading from the correct layer
#ifdef USE_MULTIVIEW
	// In order to ensure the `SpvCapabilityMultiView` is included in the SPIR-V capabilities, gl_ViewIndex must
	// be read in the shader. Without this, transpilation to Metal fails to include the multi-view variant.
	uint vi = ViewIndex;
#endif
	vec4 color = subpassLoad(input_color);
#elif defined(USE_MULTIVIEW)
	vec4 color = textureLod(source_color, vec3(uv_interp, ViewIndex), 0.0f);
#else
	vec4 color = textureLod(source_color, uv_interp, 0.0f);
#endif
	color.rgb *= params.luminance_multiplier;

	// Exposure

	float exposure = params.exposure;

#ifndef SUBPASS
	if (bool(params.flags & FLAG_USE_AUTO_EXPOSURE)) {
		exposure *= 1.0 / (texelFetch(source_auto_exposure, ivec2(0, 0), 0).r * params.luminance_multiplier / params.auto_exposure_scale);
	}
#endif

	color.rgb *= exposure;

	// Early Tonemap & SRGB Conversion
#ifndef SUBPASS
	if (bool(params.flags & FLAG_USE_FXAA)) {
		// FXAA must be performed before glow to preserve the "bleed" effect of glow.
		color.rgb = do_fxaa(color.rgb, exposure, uv_interp);
	}

	if (bool(params.flags & FLAG_USE_GLOW) && params.glow_mode == GLOW_MODE_MIX) {
		vec3 glow = gather_glow(source_glow, uv_interp) * params.luminance_multiplier;
		if (params.glow_map_strength > 0.001) {
			glow = mix(glow, texture(glow_map, uv_interp).rgb * glow, params.glow_map_strength);
		}
		color.rgb = mix(color.rgb, glow, params.glow_intensity);
	}
#endif

	color.rgb = apply_tonemapping(color.rgb, params.white);

	bool convert_to_srgb = bool(params.flags & FLAG_CONVERT_TO_SRGB);
	if (convert_to_srgb) {
		color.rgb = linear_to_srgb(color.rgb); // Regular linear -> SRGB conversion.
	}
#ifndef SUBPASS
	// Glow
	if (bool(params.flags & FLAG_USE_GLOW) && params.glow_mode != GLOW_MODE_MIX) {
		vec3 glow = gather_glow(source_glow, uv_interp) * params.glow_intensity * params.luminance_multiplier;
		if (params.glow_map_strength > 0.001) {
			glow = mix(glow, texture(glow_map, uv_interp).rgb * glow, params.glow_map_strength);
		}

		// high dynamic range -> SRGB
		glow = apply_tonemapping(glow, params.white);
		if (convert_to_srgb) {
			glow = linear_to_srgb(glow);
		}

		color.rgb = apply_glow(color.rgb, glow);
	}
#endif

	// Additional effects

	if (bool(params.flags & FLAG_USE_BCS)) {
		color.rgb = apply_bcs(color.rgb, params.bcs);
	}

	if (bool(params.flags & FLAG_USE_COLOR_CORRECTION)) {
		// apply_color_correction requires nonlinear sRGB encoding
		if (!convert_to_srgb) {
			color.rgb = linear_to_srgb(color.rgb);
		}
		color.rgb = apply_color_correction(color.rgb);
		// When convert_to_srgb is false, there is no need to convert back to
		// linear because the color correction texture sampling does this for us.
	}

	// Debanding should be done at the end of tonemapping, but before writing to the LDR buffer.
	// Otherwise, we're adding noise to an already-quantized image.

	if (bool(params.flags & FLAG_USE_8_BIT_DEBANDING)) {
		// Divide by 255 to align to 8-bit quantization.
		color.rgb += screen_space_dither(gl_FragCoord.xy, 255.0);
	} else if (bool(params.flags & FLAG_USE_10_BIT_DEBANDING)) {
		// Divide by 1023 to align to 10-bit quantization.
		color.rgb += screen_space_dither(gl_FragCoord.xy, 1023.0);
	}

	frag_color = color;
}