From ca606a5e0858dec0cccd85c393f85e61e45ab362 Mon Sep 17 00:00:00 2001
From: dmcdiar <dmcdiar@amazon.com>
Date: Wed, 30 Jun 2021 18:35:25 -0700
Subject: [PATCH] Set IBL exposure value to 0.0 while baking ReflectionProbe
 cubemaps

Signed-off-by: dmcdiar <dmcdiar@amazon.com>
---
 .../ReflectionProbe/ReflectionProbe.cpp       | 35 ++++++++++++++-----
 .../Source/ReflectionProbe/ReflectionProbe.h  |  2 ++
 2 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/Gems/Atom/Feature/Common/Code/Source/ReflectionProbe/ReflectionProbe.cpp b/Gems/Atom/Feature/Common/Code/Source/ReflectionProbe/ReflectionProbe.cpp
index 10e8f16b4c..95755fc509 100644
--- a/Gems/Atom/Feature/Common/Code/Source/ReflectionProbe/ReflectionProbe.cpp
+++ b/Gems/Atom/Feature/Common/Code/Source/ReflectionProbe/ReflectionProbe.cpp
@@ -96,16 +96,29 @@ namespace AZ
 
         void ReflectionProbe::Simulate(uint32_t probeIndex)
         {
-            if (m_buildingCubeMap && m_environmentCubeMapPass->IsFinished())
+            if (m_buildingCubeMap)
             {
-                // all faces of the cubemap have been rendered, invoke the callback
-                m_callback(m_environmentCubeMapPass->GetTextureData(), m_environmentCubeMapPass->GetTextureFormat());
-
-                // remove the pipeline
-                m_scene->RemoveRenderPipeline(m_environmentCubeMapPipelineId);
-                m_environmentCubeMapPass = nullptr;
-
-                m_buildingCubeMap = false;
+                Data::Instance<RPI::ShaderResourceGroup> sceneSrg = m_scene->GetShaderResourceGroup();
+
+                if (m_environmentCubeMapPass->IsFinished())
+                {
+                    // all faces of the cubemap have been rendered, invoke the callback
+                    m_callback(m_environmentCubeMapPass->GetTextureData(), m_environmentCubeMapPass->GetTextureFormat());
+
+                    // remove the pipeline
+                    m_scene->RemoveRenderPipeline(m_environmentCubeMapPipelineId);
+                    m_environmentCubeMapPass = nullptr;
+
+                    // restore exposure
+                    sceneSrg->SetConstant(m_iblExposureConstantIndex, m_previousExposure);
+
+                    m_buildingCubeMap = false;
+                }
+                else
+                {
+                    // set exposure to 0.0 while baking the cubemap
+                    sceneSrg->SetConstant(m_iblExposureConstantIndex, 0.0f);
+                }
             }
 
             // track if we need to update culling based on changes to the draw packets or Srg
@@ -283,6 +296,10 @@ namespace AZ
             const RPI::Ptr<RPI::ParentPass>& rootPass = environmentCubeMapPipeline->GetRootPass();
             rootPass->AddChild(m_environmentCubeMapPass);
 
+            // store the current IBL exposure value
+            Data::Instance<RPI::ShaderResourceGroup> sceneSrg = m_scene->GetShaderResourceGroup();
+            m_previousExposure = sceneSrg->GetConstant<float>(m_iblExposureConstantIndex);
+
             m_scene->AddRenderPipeline(environmentCubeMapPipeline);
         }
 
diff --git a/Gems/Atom/Feature/Common/Code/Source/ReflectionProbe/ReflectionProbe.h b/Gems/Atom/Feature/Common/Code/Source/ReflectionProbe/ReflectionProbe.h
index c354d39d53..48add33260 100644
--- a/Gems/Atom/Feature/Common/Code/Source/ReflectionProbe/ReflectionProbe.h
+++ b/Gems/Atom/Feature/Common/Code/Source/ReflectionProbe/ReflectionProbe.h
@@ -163,6 +163,8 @@ namespace AZ
             RPI::Ptr<RPI::EnvironmentCubeMapPass> m_environmentCubeMapPass = nullptr;
             RPI::RenderPipelineId m_environmentCubeMapPipelineId;
             BuildCubeMapCallback m_callback;
+            RHI::ShaderInputNameIndex m_iblExposureConstantIndex = "m_iblExposure";
+            float m_previousExposure = 0.0f;
             bool m_buildingCubeMap = false;
         };