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godot/servers/rendering/renderer_rd/shaders/effects/tonemap.glsl
Allen Pestaluky c5cf73a2e7 Optimize AgX tonemapper's handling of negative values 
This change improves performance of the AgX tonemapper by allowing two matrix multiplications to be combined into one. This comes at the cost of loss of color information that could be correctly interpreted as positive RGB values in the Rec. 2020 color space. Additionally, an insignificant amount of error is intentionally introduced to the input color value to prevent the need for a second max function call before log2. The final negative color clipping has been removed to allow the tonemapper to return negative RGB values, similar to other tonemappers in Godot.
2025-01-13 17:35:35 -05:00

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#[vertex]
#version 450
#VERSION_DEFINES
#ifdef USE_MULTIVIEW
#ifdef has_VK_KHR_multiview
#extension GL_EXT_multiview : enable
#endif
#endif
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
#ifdef has_VK_KHR_multiview
#extension GL_EXT_multiview : enable
#define ViewIndex gl_ViewIndex
#else // has_VK_KHR_multiview
#define ViewIndex 0
#endif // has_VK_KHR_multiview
#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_DEBANDING (1 << 5)
#define FLAG_CONVERT_TO_SRGB (1 << 6)
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) {
//if going to srgb, clamp from 0 to 1.
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
vec3 do_fxaa(vec3 color, float exposure, vec2 uv_interp) {
const float FXAA_REDUCE_MIN = (1.0 / 128.0);
const float FXAA_REDUCE_MUL = (1.0 / 8.0);
const float FXAA_SPAN_MAX = 8.0;
#ifdef USE_MULTIVIEW
vec3 rgbNW = textureLod(source_color, vec3(uv_interp + vec2(-0.5, -0.5) * params.pixel_size, ViewIndex), 0.0).xyz * exposure * params.luminance_multiplier;
vec3 rgbNE = textureLod(source_color, vec3(uv_interp + vec2(0.5, -0.5) * params.pixel_size, ViewIndex), 0.0).xyz * exposure * params.luminance_multiplier;
vec3 rgbSW = textureLod(source_color, vec3(uv_interp + vec2(-0.5, 0.5) * params.pixel_size, ViewIndex), 0.0).xyz * exposure * params.luminance_multiplier;
vec3 rgbSE = textureLod(source_color, vec3(uv_interp + vec2(0.5, 0.5) * params.pixel_size, ViewIndex), 0.0).xyz * exposure * params.luminance_multiplier;
#else
vec3 rgbNW = textureLod(source_color, uv_interp + vec2(-0.5, -0.5) * params.pixel_size, 0.0).xyz * exposure * params.luminance_multiplier;
vec3 rgbNE = textureLod(source_color, uv_interp + vec2(0.5, -0.5) * params.pixel_size, 0.0).xyz * exposure * params.luminance_multiplier;
vec3 rgbSW = textureLod(source_color, uv_interp + vec2(-0.5, 0.5) * params.pixel_size, 0.0).xyz * exposure * params.luminance_multiplier;
vec3 rgbSE = textureLod(source_color, uv_interp + vec2(0.5, 0.5) * params.pixel_size, 0.0).xyz * exposure * params.luminance_multiplier;
#endif
vec3 rgbM = color;
vec3 luma = vec3(0.299, 0.587, 0.114);
float lumaNW = dot(rgbNW, luma);
float lumaNE = dot(rgbNE, luma);
float lumaSW = dot(rgbSW, luma);
float lumaSE = dot(rgbSE, luma);
float lumaM = dot(rgbM, luma);
float lumaMin = min(lumaM, min(min(lumaNW, lumaNE), min(lumaSW, lumaSE)));
float lumaMax = max(lumaM, max(max(lumaNW, lumaNE), max(lumaSW, lumaSE)));
vec2 dir;
dir.x = -((lumaNW + lumaNE) - (lumaSW + lumaSE));
dir.y = ((lumaNW + lumaSW) - (lumaNE + lumaSE));
float dirReduce = max((lumaNW + lumaNE + lumaSW + lumaSE) *
(0.25 * FXAA_REDUCE_MUL),
FXAA_REDUCE_MIN);
float rcpDirMin = 1.0 / (min(abs(dir.x), abs(dir.y)) + dirReduce);
dir = min(vec2(FXAA_SPAN_MAX, FXAA_SPAN_MAX),
max(vec2(-FXAA_SPAN_MAX, -FXAA_SPAN_MAX),
dir * rcpDirMin)) *
params.pixel_size;
#ifdef USE_MULTIVIEW
vec3 rgbA = 0.5 * exposure * (textureLod(source_color, vec3(uv_interp + dir * (1.0 / 3.0 - 0.5), ViewIndex), 0.0).xyz + textureLod(source_color, vec3(uv_interp + dir * (2.0 / 3.0 - 0.5), ViewIndex), 0.0).xyz) * params.luminance_multiplier;
vec3 rgbB = rgbA * 0.5 + 0.25 * exposure * (textureLod(source_color, vec3(uv_interp + dir * -0.5, ViewIndex), 0.0).xyz + textureLod(source_color, vec3(uv_interp + dir * 0.5, ViewIndex), 0.0).xyz) * params.luminance_multiplier;
#else
vec3 rgbA = 0.5 * exposure * (textureLod(source_color, uv_interp + dir * (1.0 / 3.0 - 0.5), 0.0).xyz + textureLod(source_color, uv_interp + dir * (2.0 / 3.0 - 0.5), 0.0).xyz) * params.luminance_multiplier;
vec3 rgbB = rgbA * 0.5 + 0.25 * exposure * (textureLod(source_color, uv_interp + dir * -0.5, 0.0).xyz + textureLod(source_color, uv_interp + dir * 0.5, 0.0).xyz) * params.luminance_multiplier;
#endif
float lumaB = dot(rgbB, luma);
if ((lumaB < lumaMin) || (lumaB > lumaMax)) {
return rgbA;
} else {
return rgbB;
}
}
#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).
vec3 screen_space_dither(vec2 frag_coord) {
// Iestyn's RGB dither (7 asm instructions) from Portal 2 X360, slightly modified for VR.
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.
return (dither.rgb - 0.5) / 255.0;
}
void main() {
#ifdef SUBPASS
// SUBPASS and USE_MULTIVIEW can be combined but in that case we're already reading from the correct layer
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);
if (bool(params.flags & FLAG_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 (bool(params.flags & FLAG_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)) {
color.rgb = apply_color_correction(color.rgb);
}
if (bool(params.flags & FLAG_USE_DEBANDING)) {
// 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.
color.rgb += screen_space_dither(gl_FragCoord.xy);
}
frag_color = color;
}
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