Autodesk · sebastienblor · May 20, 2026 · May 20, 2026
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -6,6 +6,7 @@
 ### Features
 
 - [usd#2619](https://github.com/Autodesk/arnold-usd/issues/2619) - Add MtoA scene index plugin for MayaHydra support of custom attributes
+- [usd#2650](https://github.com/Autodesk/arnold-usd/issues/2650) - Optionally use Hydra Render Settings primitive instead of settings map
 - [usd#2583](https://github.com/Autodesk/arnold-usd/issues/2583) - Support nested instancers with lightweight shape instancing
 - [usd#2594](https://github.com/Autodesk/arnold-usd/issues/2594) - Use a global map for shared arrays
 - [usd#2608](https://github.com/Autodesk/arnold-usd/issues/2608) - Implement preliminary support for ParticleField3DGaussianSplat.

diff --git a/cmake/utils/options.cmake b/cmake/utils/options.cmake
@@ -49,7 +49,6 @@ option(BUILD_USDGENSCHEMA_ARNOLD "Build and use a custom usdgenschema" OFF)
 # Configurations:
 option(ENABLE_HYDRA_IN_USD_PROCEDURAL "Enable hydra in the procedural" ON)
 option(ENABLE_SHARED_ARRAYS "Enable using shared arrays" OFF)
-option(ENABLE_HYDRA2_RENDERSETTINGS "Enable using RenderSetting hydra prim" OFF)
 option(ENABLE_SCENE_INDEX_IN_BUNDLE "Add the scene index filters in the bundle" OFF)
 option(ENABLE_TRACING "Enable USD trace instrumentation (TRACE_FUNCTION/TRACE_SCOPE)." OFF)
 option(MTOA_BUILD "Build MtoA-specific plugins (e.g. the ai<Name> primvar remap scene index)" OFF)

diff --git a/libs/render_delegate/CMakeLists.txt b/libs/render_delegate/CMakeLists.txt
@@ -72,9 +72,6 @@ target_link_libraries(render_delegate INTERFACE common)
 if (ENABLE_SHARED_ARRAYS)
     target_compile_definitions(render_delegate PUBLIC ENABLE_SHARED_ARRAYS=1)
 endif()
-if (ENABLE_HYDRA2_RENDERSETTINGS)
-    target_compile_definitions(render_delegate PUBLIC ENABLE_HYDRA2_RENDERSETTINGS=1)
-endif()
 if (HYDRA_NORMALIZE_DEPTH)
     target_compile_definitions(render_delegate PUBLIC HYDRA_NORMALIZE_DEPTH=1)
 endif()

diff --git a/libs/render_delegate/SConscript b/libs/render_delegate/SConscript
@@ -58,9 +58,6 @@ if local_env['USD_HAS_FULLSCREEN_SHADER']:
 if local_env['ENABLE_SHARED_ARRAYS']:
     local_env.Append(CPPDEFINES = ['ENABLE_SHARED_ARRAYS'])
 
-if local_env['ENABLE_HYDRA2_RENDERSETTINGS']:
-    local_env.Append(CPPDEFINES = ['ENABLE_HYDRA2_RENDERSETTINGS'])
-
 if local_env['BUILD_SCENE_INDEX_PLUGIN']:
     local_env.Append(CPPDEFINES = ['ENABLE_SCENE_INDEX'])
 

diff --git a/libs/render_delegate/reader.cpp b/libs/render_delegate/reader.cpp
@@ -35,6 +35,9 @@ PXR_NAMESPACE_USING_DIRECTIVE
 // clang-format off
 TF_DEFINE_PRIVATE_TOKENS(_tokens,
     ((hydraProcCamera, "/ArnoldHydraProceduralCamera"))
+    (renderSettingsSrc)
+    (hydraSceneRenderSettingsSrc)
+
 );
 
 // check pxr/imaging/hd/testenv/testHdRenderIndex.cpp
@@ -299,24 +302,22 @@ void HydraArnoldReader::ReadStage(UsdStageRefPtr stage,
             TRACE_SCOPE("ChooseRenderSettings");
             ChooseRenderSettings(stage, _renderSettings, _time);
         }
-// TODO HERE WE COULD CHECK IF WE WANT TO USE HYDRA2
+
         if (!_renderSettings.empty()) {
             TRACE_SCOPE("ReadRenderSettings");
             // Sets the default parameters on the Arnold option node (AA_samples, GI_diffuse_depth, ...)
             SetArnoldDefaultOptions(_universe);
-#ifdef ENABLE_HYDRA2_RENDERSETTINGS
             // We want to use the RenderSetting hydra prim only if we use the scene index system
             if (_useSceneIndex) {
                 // TODO set metadata only if it it not already set
+                VtValue val(_tokens->hydraSceneRenderSettingsSrc);
+                // Tell the arnold render delegate to use the hydra render settings
+                arnoldRenderDelegate->SetRenderSetting(_tokens->renderSettingsSrc, val);
                 stage->SetMetadata(UsdRenderTokens->renderSettingsPrimPath, _renderSettings);
             } else {
                 UsdPrim renderSettingsPrim = stage->GetPrimAtPath(SdfPath(_renderSettings));
                 ReadRenderSettings(renderSettingsPrim, arnoldRenderDelegate->GetAPIAdapter(), this, _time, _universe, _renderCameraPath);
             }
-#else
-            UsdPrim renderSettingsPrim = stage->GetPrimAtPath(SdfPath(_renderSettings));
-            ReadRenderSettings(renderSettingsPrim, arnoldRenderDelegate->GetAPIAdapter(), this, _time, _universe, _renderCameraPath);
-#endif
         }
     } 
 

diff --git a/libs/render_delegate/render_delegate.cpp b/libs/render_delegate/render_delegate.cpp
@@ -68,10 +68,7 @@
 #include "render_pass.h"
 #include "volume.h"
 #include <cctype>
-
-#ifdef ENABLE_HYDRA2_RENDERSETTINGS
 #include "render_settings.h"
-#endif
 
 PXR_NAMESPACE_OPEN_SCOPE
 
@@ -112,6 +109,9 @@ TF_DEFINE_PRIVATE_TOKENS(_tokens,
     (GeometryLight)
     (dataWindowNDC)
     (resolution)
+    (renderSettingsSrc)
+    (hydraSceneRenderSettingsSrc)
+
     // The following tokens are also defined in read_options.cpp, we need them
     // here for the conversion from TfToken to HdFormat, while in read_options they
     // are used for the conversion of HdFormat to TfToken.
@@ -294,11 +294,7 @@ inline const TfTokenVector& _SupportedBprimTypes(bool ownsUniverse)
     } else
 #endif
     {
-#ifdef ENABLE_HYDRA2_RENDERSETTINGS
         static const TfTokenVector r{HdPrimTypeTokens->renderBuffer, _tokens->openvdbAsset, HdPrimTypeTokens->renderSettings};
-#else
-        static const TfTokenVector r{HdPrimTypeTokens->renderBuffer, _tokens->openvdbAsset};
-#endif
         return r;
     }
 }
@@ -716,6 +712,12 @@ void HdArnoldRenderDelegate::_SetRenderSetting(const TfToken& _key, const VtValu
         _ParseDelegateRenderProducts(_value);
         return;
     }
+    if (_key == _tokens->renderSettingsSrc) {
+        if (_value.IsHolding<TfToken>()) {
+            TfToken renderSettingsSrc = _value.UncheckedGet<TfToken>();
+            _useHydraRenderSettings = (renderSettingsSrc == _tokens->hydraSceneRenderSettingsSrc);
+        }
+    }
     TfToken key;
     _RemoveArnoldGlobalPrefix(_key, key);
 
@@ -1126,15 +1128,6 @@ HdRenderSettingDescriptorList HdArnoldRenderDelegate::GetRenderSettingDescriptor
     return ret;
 }
 
-// for testing in batch mode. TODO: correctly check the if we can and want to use the hydra render settings
-bool HdArnoldRenderDelegate::IsUsingHydraRenderSettings() const { 
-#ifdef ENABLE_HYDRA2_RENDERSETTINGS
-    return true; 
-#else
-    return false;
-#endif
-}
-
 VtDictionary HdArnoldRenderDelegate::GetRenderStats() const
 {
     VtDictionary stats;
@@ -1367,14 +1360,9 @@ HdBprim* HdArnoldRenderDelegate::CreateBprim(const TfToken& typeId, const SdfPat
 #if PXR_VERSION >= 2208
     // Only support render settings when we don't own the universe (procedural context).
     // When we own the universe (batch context), settings come through SetRenderSettings.
-#ifdef ENABLE_HYDRA2_RENDERSETTINGS
     if (typeId == HdPrimTypeTokens->renderSettings /*&& !_renderDelegateOwnsUniverse*/) {
-        return new HdArnoldRenderSettings(bprimId);
+        return new HdArnoldRenderSettings(this, bprimId);
     }
-#else
-    if (typeId == HdPrimTypeTokens->renderSettings)
-        return nullptr;
-#endif // ENABLE_HYDRA2_RENDERSETTINGS
 #endif // PXR_VERSION >= 2208
 
     TF_CODING_ERROR("Unknown Bprim Type %s", typeId.GetText());

diff --git a/libs/render_delegate/render_delegate.h b/libs/render_delegate/render_delegate.h
@@ -699,7 +699,7 @@ class HdArnoldRenderDelegate final : public HdRenderDelegate {
     void SetHasCryptomatte(bool b);
     void SetInstancerCryptoOffset(AtNode *node, size_t numInstances);
 
-    bool IsUsingHydraRenderSettings() const;
+    bool IsUsingHydraRenderSettings() const {return _useHydraRenderSettings;}
 
 private:    
     HdArnoldRenderDelegate(const HdArnoldRenderDelegate&) = delete;
@@ -827,6 +827,7 @@ class HdArnoldRenderDelegate final : public HdRenderDelegate {
     bool _enableNodesDestruction = true;
     bool _supportShapeInstancing = true;
     bool _forceIgnoreMotionBlur = false;
+    bool _useHydraRenderSettings = false;
     std::unordered_map<std::string, AtNode *> _nodeNames;
 
     // We store a list of functions that must be run once all the prims are synced

diff --git a/libs/render_delegate/render_pass.cpp b/libs/render_delegate/render_pass.cpp
@@ -47,9 +47,7 @@
 #include "nodes/nodes.h"
 #include "utils.h"
 #include "rendersettings_utils.h"
-#ifdef ENABLE_HYDRA2_RENDERSETTINGS
 #include "render_settings.h"
-#endif
 #include <regex>
 #include <cmath>
 #include <cstdio>
@@ -501,7 +499,6 @@ HdArnoldRenderPass::~HdArnoldRenderPass()
 void HdArnoldRenderPass::_Execute(const HdRenderPassStateSharedPtr& renderPassState, const TfTokenVector& renderTags)
 {
     HdArnoldRenderParam* renderParam = reinterpret_cast<HdArnoldRenderParam*>(_renderDelegate->GetRenderParam());
-#ifdef ENABLE_HYDRA2_RENDERSETTINGS
     if (_renderDelegate->IsUsingHydraRenderSettings()) {
         // If we are using the hydra render settings, we let the render settings prim handle the conversion.
         // We need to provide a camera pas
@@ -529,7 +526,6 @@ void HdArnoldRenderPass::_Execute(const HdRenderPassStateSharedPtr& renderPassSt
         }
         // We couldn't use the render settings, we fall back to the original code
     }
-#endif
 
     if (_renderDelegate->SetRenderTags(renderTags)) {
         // Render tags have changed, let's iterate through all the nodes
@@ -1341,7 +1337,6 @@ void HdArnoldRenderPass::_ClearRenderBuffers()
     decltype(_renderBuffers){}.swap(_renderBuffers);
 }
 
-#ifdef ENABLE_HYDRA2_RENDERSETTINGS
 #if PXR_VERSION >= 2308
 HdArnoldRenderSettings*
 HdArnoldRenderPass::_GetHydraRenderSettingsPrim() const
@@ -1354,6 +1349,5 @@ HdArnoldRenderPass::_GetHydraRenderSettingsPrim() const
         renderParam->GetHydraRenderSettingsPrimPath()));
 }
 #endif
-#endif
 
 PXR_NAMESPACE_CLOSE_SCOPE
diff --git a/libs/render_delegate/render_pass.h b/libs/render_delegate/render_pass.h
@@ -50,9 +50,7 @@
 
 PXR_NAMESPACE_OPEN_SCOPE
 
-#ifdef ENABLE_HYDRA2_RENDERSETTINGS
 class HdArnoldRenderSettings;
-#endif
 
 /// Utility class for handling Render Passes.
 class HdArnoldRenderPass : public HdRenderPass {
@@ -95,14 +93,12 @@ class HdArnoldRenderPass : public HdRenderPass {
     HDARNOLD_API
     void _ClearRenderBuffers();
 
-#ifdef ENABLE_HYDRA2_RENDERSETTINGS
 #if PXR_VERSION >= 2308
     /// Gets the driving hydra render settings prim.
     ///
     /// @return Pointer to the HdArnoldRenderSettings prim.
     HdArnoldRenderSettings* _GetHydraRenderSettingsPrim() const;
 #endif
-#endif
 
 private:
     HdArnoldRenderBufferStorage _renderBuffers;   ///< Render buffer storage.