Initial tonemapping options (bevyengine#7594)

# Objective

Splits tone mapping from bevyengine#6677 into a separate PR.
Address bevyengine#2264.
Adds tone mapping options:
- None: Bypasses tonemapping for instances where users want colors output to match those set.
- Reinhard
- Reinhard Luminance: Bevy's exiting tonemapping
- [ACES](https://github.com/TheRealMJP/BakingLab/blob/master/BakingLab/ACES.hlsl) (Fitted version, based on the same implementation that Godot 4 uses) see bevyengine#2264
- [AgX](https://github.com/sobotka/AgX)
- SomewhatBoringDisplayTransform
- TonyMcMapface
- Blender Filmic

This PR also adds support for EXR images so they can be used to compare tonemapping options with reference images.

## Migration Guide
- Tonemapping is now an enum with NONE and the various tonemappers.
- The DebandDither is now a separate component.




Co-authored-by: JMS55 <[email protected]>

Cargo.toml

@@ -50,6 +50,7 @@ default = [
   "x11",
   "filesystem_watcher",
   "android_shared_stdcxx",
+  "tonemapping_luts"
 ]
 
 # Force dynamic linking, which improves iterative compile times
@@ -78,6 +79,7 @@ trace = ["bevy_internal/trace"]
 wgpu_trace = ["bevy_internal/wgpu_trace"]
 
 # Image format support for texture loading (PNG and HDR are enabled by default)
+exr = ["bevy_internal/exr"]
 hdr = ["bevy_internal/hdr"]
 png = ["bevy_internal/png"]
 tga = ["bevy_internal/tga"]
@@ -131,6 +133,9 @@ android_shared_stdcxx = ["bevy_internal/android_shared_stdcxx"]
 # These trace events are expensive even when off, thus they require compile time opt-in.
 detailed_trace = ["bevy_internal/detailed_trace"]
 
+# Include tonemapping LUT KTX2 files.
+tonemapping_luts = ["bevy_internal/tonemapping_luts"]
+
 [dependencies]
 bevy_dylib = { path = "crates/bevy_dylib", version = "0.9.0", default-features = false, optional = true }
 bevy_internal = { path = "crates/bevy_internal", version = "0.9.0", default-features = false }
@@ -389,6 +394,17 @@ description = "Loads and renders a glTF file as a scene"
 category = "3D Rendering"
 wasm = true
 
+[[example]]
+name = "tonemapping"
+path = "examples/3d/tonemapping.rs"
+required-features = ["ktx2", "zstd"]
+
+[package.metadata.example.tonemapping]
+name = "Tonemapping"
+description = "Compares tonemapping options"
+category = "3D Rendering"
+wasm = true
+
 [[example]]
 name = "fxaa"
 path = "examples/3d/fxaa.rs"

assets/shaders/tonemapping_test_patterns.wgsl

@@ -0,0 +1,64 @@
+#import bevy_pbr::mesh_view_bindings
+#import bevy_pbr::mesh_bindings
+#import bevy_pbr::utils
+
+#ifdef TONEMAP_IN_SHADER
+#import bevy_core_pipeline::tonemapping
+#endif
+
+struct FragmentInput {
+    @builtin(front_facing) is_front: bool,
+    @builtin(position) frag_coord: vec4<f32>,
+    #import bevy_pbr::mesh_vertex_output
+};
+
+// Sweep across hues on y axis with value from 0.0 to +15EV across x axis 
+// quantized into 24 steps for both axis.
+fn color_sweep(uv: vec2<f32>) -> vec3<f32> {
+    var uv = uv;
+    let steps = 24.0;
+    uv.y = uv.y * (1.0 + 1.0 / steps);
+    let ratio = 2.0;
+
+    let h = PI * 2.0 * floor(1.0 + steps * uv.y) / steps;
+    let L = floor(uv.x * steps * ratio) / (steps * ratio) - 0.5;
+
+    var color = vec3(0.0);
+    if uv.y < 1.0 { 
+        color = cos(h + vec3(0.0, 1.0, 2.0) * PI * 2.0 / 3.0);
+        let maxRGB = max(color.r, max(color.g, color.b));
+        let minRGB = min(color.r, min(color.g, color.b));
+        color = exp(15.0 * L) * (color - minRGB) / (maxRGB - minRGB);
+    } else {
+        color = vec3(exp(15.0 * L));
+    }
+    return color;
+}
+
+fn hsv_to_srgb(c: vec3<f32>) -> vec3<f32> {
+    let K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
+    let p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
+    return c.z * mix(K.xxx, clamp(p - K.xxx, vec3(0.0), vec3(1.0)), c.y);
+}
+
+// Generates a continuous sRGB sweep.
+fn continuous_hue(uv: vec2<f32>) -> vec3<f32> {
+    return hsv_to_srgb(vec3(uv.x, 1.0, 1.0)) * max(0.0, exp2(uv.y * 9.0) - 1.0);
+}
+
+@fragment
+fn fragment(in: FragmentInput) -> @location(0) vec4<f32> {
+    var uv = in.uv;
+    var out = vec3(0.0);
+    if uv.y > 0.5 {
+        uv.y = 1.0 - uv.y;
+        out = color_sweep(vec2(uv.x, uv.y * 2.0));
+    } else {
+        out = continuous_hue(vec2(uv.y * 2.0, uv.x));
+    }
+    var color = vec4(out, 1.0);
+#ifdef TONEMAP_IN_SHADER
+    color = tone_mapping(color);
+#endif
+    return color;
+}

crates/bevy_core_pipeline/Cargo.toml

@@ -15,6 +15,7 @@ keywords = ["bevy"]
 [features]
 trace = []
 webgl = []
+tonemapping_luts = []
 
 [dependencies]
 # bevy

crates/bevy_core_pipeline/src/core_2d/camera_2d.rs

@@ -1,4 +1,7 @@
-use crate::{clear_color::ClearColorConfig, tonemapping::Tonemapping};
+use crate::{
+    clear_color::ClearColorConfig,
+    tonemapping::{DebandDither, Tonemapping},
+};
 use bevy_ecs::prelude::*;
 use bevy_reflect::Reflect;
 use bevy_render::{
@@ -27,6 +30,7 @@ pub struct Camera2dBundle {
     pub global_transform: GlobalTransform,
     pub camera_2d: Camera2d,
     pub tonemapping: Tonemapping,
+    pub deband_dither: DebandDither,
 }
 
 impl Default for Camera2dBundle {
@@ -67,7 +71,8 @@ impl Camera2dBundle {
             global_transform: Default::default(),
             camera: Camera::default(),
             camera_2d: Camera2d::default(),
-            tonemapping: Tonemapping::Disabled,
+            tonemapping: Tonemapping::None,
+            deband_dither: DebandDither::Disabled,
         }
     }
 }

crates/bevy_core_pipeline/src/core_3d/camera_3d.rs

@@ -1,12 +1,15 @@
-use crate::{clear_color::ClearColorConfig, tonemapping::Tonemapping};
+use crate::{
+    clear_color::ClearColorConfig,
+    tonemapping::{DebandDither, Tonemapping},
+};
 use bevy_ecs::prelude::*;
 use bevy_reflect::{Reflect, ReflectDeserialize, ReflectSerialize};
 use bevy_render::{
     camera::{Camera, CameraRenderGraph, Projection},
     extract_component::ExtractComponent,
     primitives::Frustum,
     render_resource::LoadOp,
-    view::VisibleEntities,
+    view::{ColorGrading, VisibleEntities},
 };
 use bevy_transform::prelude::{GlobalTransform, Transform};
 use serde::{Deserialize, Serialize};
@@ -59,23 +62,25 @@ pub struct Camera3dBundle {
     pub global_transform: GlobalTransform,
     pub camera_3d: Camera3d,
     pub tonemapping: Tonemapping,
+    pub dither: DebandDither,
+    pub color_grading: ColorGrading,
 }
 
 // NOTE: ideally Perspective and Orthographic defaults can share the same impl, but sadly it breaks rust's type inference
 impl Default for Camera3dBundle {
     fn default() -> Self {
         Self {
             camera_render_graph: CameraRenderGraph::new(crate::core_3d::graph::NAME),
-            tonemapping: Tonemapping::Enabled {
-                deband_dither: true,
-            },
             camera: Default::default(),
             projection: Default::default(),
             visible_entities: Default::default(),
             frustum: Default::default(),
             transform: Default::default(),
             global_transform: Default::default(),
             camera_3d: Default::default(),
+            tonemapping: Tonemapping::ReinhardLuminance,
+            dither: DebandDither::Enabled,
+            color_grading: ColorGrading::default(),
         }
     }
 }

crates/bevy_core_pipeline/src/tonemapping/luts/info.txt

@@ -0,0 +1,22 @@
+--- Process for recreating AgX-default_contrast.ktx2 ---
+Download: 
+https://github.com/MrLixm/AgXc/blob/898198e0490b0551ed81412a0c22e0b72fffb7cd/obs/obs-script/AgX-default_contrast.lut.png
+Convert to vertical strip exr with: 
+https://gist.github.com/DGriffin91/fc8e0cfd55aaa175ac10199403bc19b8
+Convert exr to 3D ktx2 with:
+https://gist.github.com/DGriffin91/49401c43378b58bce32059291097d4ca
+
+--- Process for recreating tony_mc_mapface.ktx2 ---
+Download: 
+https://github.com/h3r2tic/tony-mc-mapface/blob/909e51c8a74251fd828770248476cb084081e08c/tony_mc_mapface.dds
+Convert dds to 3D ktx2 with:
+https://gist.github.com/DGriffin91/49401c43378b58bce32059291097d4ca
+
+--- Process for recreating Blender_-11_12.ktx2 ---
+Create LUT stimulus with:
+https://gist.github.com/DGriffin91/e119bf32b520e219f6e102a6eba4a0cf
+Open LUT image in Blender's image editor and make sure color space is set to linear.
+Export from Blender as 32bit EXR, override color space to Filmic sRGB.
+Import EXR back into blender set color space to sRGB, then export as 32bit EXR override color space to linear.
+Convert exr to 3D ktx2 with:
+https://gist.github.com/DGriffin91/49401c43378b58bce32059291097d4ca