MAYA-109927: Remove dependency on boost::hash_combine.

doc/codingGuidelines.md

@@ -221,14 +221,15 @@ Respect the minimum supported version for Maya and USD stated in [build.md](http
 Recent extensions to the C++ standard introduce many features previously only found in [boost](http://boost.org). To avoid introducing additional dependencies, developers should strive to use functionality in the C++ std over boost. If you encounter usage of boost in the code, consider converting this to the equivalent std mechanism. 
 Our library currently has the following boost dependencies:
 * `boost::python`
-* `boost::hash_combine` (see  [this proposal](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0814r0.pdf) )
 * `boost::make_shared` (preferable to replace with `std::shared_ptr`)
 
 ***Update:***
 * `boost::filesystem` and `boost::system` are removed. Until the transition to C++17 std::filesystem, [ghc::filesystem](https://github.com/gulrak/filesystem) must be used as an alternative across the project.
 
 * Dependency on `boost::thread` is removed from Animal Logic plugin.
 
+* `boost::hash_combine` is replaced with `MayaUsd::hash_combine` and should be used instead across the project.
+
 ## Modern C++
 Our goal is to develop [maya-usd](https://github.com/autodesk/maya-usd) following modern C++ practices. We’ll follow the [C++ Core Guidelines](http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines) and pay attention to:
 * `using` (vs `typedef`) keyword

lib/mayaUsd/render/mayaToHydra/renderOverride.cpp

@@ -24,6 +24,7 @@
 #include <hdMaya/delegates/sceneDelegate.h>
 #include <hdMaya/utils.h>
 #include <mayaUsd/render/px_vp20/utils.h>
+#include <mayaUsd/utils/hash.h>
 
 #include <pxr/base/gf/matrix4d.h>
 #include <pxr/base/tf/instantiateSingleton.h>
@@ -47,8 +48,6 @@
 #include <maya/MTimerMessage.h>
 #include <maya/MUiMessage.h>
 
-#include <boost/functional/hash.hpp>
-
 #include <atomic>
 #include <chrono>
 #include <exception>
@@ -169,10 +168,10 @@ void ResolveUniqueHits_Workaround(const HdxPickHitVector& inHits, HdxPickHitVect
         const HdxPickHit& hit = inHits[i];
 
         size_t hash = 0;
-        boost::hash_combine(hash, hit.delegateId.GetHash());
-        boost::hash_combine(hash, hit.objectId.GetHash());
-        boost::hash_combine(hash, hit.instancerId.GetHash());
-        boost::hash_combine(hash, hit.instanceIndex);
+        MayaUsd::hash_combine(hash, hit.delegateId.GetHash());
+        MayaUsd::hash_combine(hash, hit.objectId.GetHash());
+        MayaUsd::hash_combine(hash, hit.instancerId.GetHash());
+        MayaUsd::hash_combine(hash, hit.instanceIndex);
 
         // As an optimization, keep track of the previous hash value and
         // reject indices that match it without performing a map lookup.

lib/mayaUsd/render/pxrUsdMayaGL/renderParams.h

@@ -18,11 +18,11 @@
 
 /// \file pxrUsdMayaGL/renderParams.h
 
+#include <mayaUsd/utils/hash.h>
+
 #include <pxr/base/gf/vec4f.h>
 #include <pxr/pxr.h>
 
-#include <boost/functional/hash.hpp>
-
 PXR_NAMESPACE_OPEN_SCOPE
 
 struct PxrMayaHdRenderParams
@@ -40,8 +40,11 @@ struct PxrMayaHdRenderParams
     size_t Hash() const
     {
         size_t hash = size_t(enableLighting);
-        boost::hash_combine(hash, useWireframe);
-        boost::hash_combine(hash, wireframeColor);
+        MayaUsd::hash_combine(hash, useWireframe);
+        MayaUsd::hash_combine(hash, wireframeColor[0]);
+        MayaUsd::hash_combine(hash, wireframeColor[1]);
+        MayaUsd::hash_combine(hash, wireframeColor[2]);
+        MayaUsd::hash_combine(hash, wireframeColor[3]);
 
         return hash;
     }

lib/mayaUsd/render/vp2RenderDelegate/render_delegate.cpp

@@ -23,6 +23,7 @@
 #include "render_pass.h"
 
 #include <mayaUsd/render/vp2ShaderFragments/shaderFragments.h>
+#include <mayaUsd/utils/hash.h>
 
 #include <pxr/imaging/hd/bprim.h>
 #include <pxr/imaging/hd/camera.h>
@@ -33,7 +34,6 @@
 
 #include <maya/MProfiler.h>
 
-#include <boost/functional/hash.hpp>
 #include <tbb/reader_writer_lock.h>
 #include <tbb/spin_rw_mutex.h>
 
@@ -134,10 +134,10 @@ struct MColorHash
     std::size_t operator()(const MColor& color) const
     {
         std::size_t seed = 0;
-        boost::hash_combine(seed, color.r);
-        boost::hash_combine(seed, color.g);
-        boost::hash_combine(seed, color.b);
-        boost::hash_combine(seed, color.a);
+        MayaUsd::hash_combine(seed, color.r);
+        MayaUsd::hash_combine(seed, color.g);
+        MayaUsd::hash_combine(seed, color.b);
+        MayaUsd::hash_combine(seed, color.a);
         return seed;
     }
 };
@@ -358,21 +358,21 @@ struct MSamplerStateDescHash
     std::size_t operator()(const MHWRender::MSamplerStateDesc& desc) const
     {
         std::size_t seed = 0;
-        boost::hash_combine(seed, desc.filter);
-        boost::hash_combine(seed, desc.comparisonFn);
-        boost::hash_combine(seed, desc.addressU);
-        boost::hash_combine(seed, desc.addressV);
-        boost::hash_combine(seed, desc.addressW);
-        boost::hash_combine(seed, desc.borderColor[0]);
-        boost::hash_combine(seed, desc.borderColor[1]);
-        boost::hash_combine(seed, desc.borderColor[2]);
-        boost::hash_combine(seed, desc.borderColor[3]);
-        boost::hash_combine(seed, desc.mipLODBias);
-        boost::hash_combine(seed, desc.minLOD);
-        boost::hash_combine(seed, desc.maxLOD);
-        boost::hash_combine(seed, desc.maxAnisotropy);
-        boost::hash_combine(seed, desc.coordCount);
-        boost::hash_combine(seed, desc.elementIndex);
+        MayaUsd::hash_combine(seed, desc.filter);
+        MayaUsd::hash_combine(seed, desc.comparisonFn);
+        MayaUsd::hash_combine(seed, desc.addressU);
+        MayaUsd::hash_combine(seed, desc.addressV);
+        MayaUsd::hash_combine(seed, desc.addressW);
+        MayaUsd::hash_combine(seed, desc.borderColor[0]);
+        MayaUsd::hash_combine(seed, desc.borderColor[1]);
+        MayaUsd::hash_combine(seed, desc.borderColor[2]);
+        MayaUsd::hash_combine(seed, desc.borderColor[3]);
+        MayaUsd::hash_combine(seed, desc.mipLODBias);
+        MayaUsd::hash_combine(seed, desc.minLOD);
+        MayaUsd::hash_combine(seed, desc.maxLOD);
+        MayaUsd::hash_combine(seed, desc.maxAnisotropy);
+        MayaUsd::hash_combine(seed, desc.coordCount);
+        MayaUsd::hash_combine(seed, desc.elementIndex);
         return seed;
     }
 };

lib/mayaUsd/utils/CMakeLists.txt

@@ -28,6 +28,7 @@ set(HEADERS
     util.h
     utilFileSystem.h
     utilSerialization.h
+    hash.h
 )
 
 # -----------------------------------------------------------------------------

lib/mayaUsd/utils/hash.h

@@ -0,0 +1,38 @@
+//
+// Copyright 2021 Autodesk
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+#ifndef MAYAUSD_UTILS_HASH_H
+#define MAYAUSD_UTILS_HASH_H
+
+#include <mayaUsd/base/api.h>
+
+#include <functional>
+
+namespace MAYAUSD_NS_DEF {
+
+// hash combiner taken from:
+// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0814r0.pdf
+
+// boost::hash implementation also relies on the same algorithm:
+// https://www.boost.org/doc/libs/1_64_0/boost/functional/hash/hash.hpp
+
+template <typename T> inline void hash_combine(size_t& seed, const T& value)
+{
+    ::std::hash<T> hasher;
+    seed ^= hasher(value) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
+}
+} // namespace MAYAUSD_NS_DEF
+
+#endif // MAYAUSD_UTILS_HASH_H

lib/usd/hdMaya/adapters/materialAdapter.cpp

@@ -20,6 +20,7 @@
 #include <hdMaya/adapters/mayaAttrs.h>
 #include <hdMaya/adapters/tokens.h>
 #include <hdMaya/utils.h>
+#include <mayaUsd/utils/hash.h>
 
 #include <pxr/base/tf/stl.h>
 #include <pxr/base/tf/token.h>
@@ -258,9 +259,9 @@ class HdMayaShadingEngineAdapter : public HdMayaMaterialAdapter
     {
         auto       hash = filePath.Hash();
         const auto wrapping = GetFileTextureWrappingParams(fileObj);
-        boost::hash_combine(hash, GetDelegate()->GetParams().textureMemoryPerTexture);
-        boost::hash_combine(hash, std::get<0>(wrapping));
-        boost::hash_combine(hash, std::get<1>(wrapping));
+        MayaUsd::hash_combine(hash, GetDelegate()->GetParams().textureMemoryPerTexture);
+        MayaUsd::hash_combine(hash, std::get<0>(wrapping));
+        MayaUsd::hash_combine(hash, std::get<1>(wrapping));
         return HdTextureResource::ID(hash);
     }