From ab579c89c09edff0baab57d1392b66e12a7f1138 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E7=A0=94=E7=A9=B6=E7=A4=BE=E4=BA=A4?= <cryscan@umich.edu>
Date: Sun, 26 Jun 2022 00:00:23 +0000
Subject: [PATCH] Separate PBR and tone mapping into 2 functions (#5078)

# Objective

- Allow custom shaders to reuse the HDR results of PBR.

## Solution

- Separate `pbr()` and `tone_mapping()` into 2 functions in `pbr_functions.wgsl`.
---
 crates/bevy_pbr/src/render/pbr.wgsl           | 2 +-
 crates/bevy_pbr/src/render/pbr_functions.wgsl | 9 ++++++---
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/crates/bevy_pbr/src/render/pbr.wgsl b/crates/bevy_pbr/src/render/pbr.wgsl
index 3f169d5104f665..f4ba112e6e5553 100644
--- a/crates/bevy_pbr/src/render/pbr.wgsl
+++ b/crates/bevy_pbr/src/render/pbr.wgsl
@@ -85,7 +85,7 @@ fn fragment(in: FragmentInput) -> [[location(0)]] vec4<f32> {
         );
         pbr_input.V = calculate_view(in.world_position, pbr_input.is_orthographic);
 
-        output_color = pbr(pbr_input);
+        output_color = tone_mapping(pbr(pbr_input));
     }
 
     return output_color;
diff --git a/crates/bevy_pbr/src/render/pbr_functions.wgsl b/crates/bevy_pbr/src/render/pbr_functions.wgsl
index a2349fcbdeee38..04986fad1586eb 100644
--- a/crates/bevy_pbr/src/render/pbr_functions.wgsl
+++ b/crates/bevy_pbr/src/render/pbr_functions.wgsl
@@ -186,11 +186,14 @@ fn pbr(
         cluster_index,
     );
 
+    return output_color;
+}
+
+fn tone_mapping(in: vec4<f32>) -> vec4<f32> {
     // tone_mapping
-    output_color = vec4<f32>(reinhard_luminance(output_color.rgb), output_color.a);
+    return vec4<f32>(reinhard_luminance(in.rgb), in.a);
+    
     // Gamma correction.
     // Not needed with sRGB buffer
     // output_color.rgb = pow(output_color.rgb, vec3(1.0 / 2.2));
-
-    return output_color;
 }