Add comment on changed prime numbers

Signed-off-by: Benedikt Mersch <benedikt.mersch@gmail.com>
AcademySoftwareFoundation · Jun 26, 2023 · f18dc75 · f18dc75
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diff --git a/nanovdb/nanovdb/NanoVDB.h b/nanovdb/nanovdb/NanoVDB.h
@@ -1134,6 +1134,8 @@ class Coord
 
     /// @brief Return a hash key derived from the existing coordinates.
     /// @details For details on this hash function please see the VDB paper.
+    /// The prime numbers are modified based on the ACM Transactions on Graphics paper:
+    /// "Real-time 3D reconstruction at scale using voxel hashing"
     template<int Log2N = 3 + 4 + 5>
     __hostdev__ uint32_t hash() const { return ((1 << Log2N) - 1) & (mVec[0] * 73856093 ^ mVec[1] * 19349669 ^ mVec[2] * 83492791); }
 

diff --git a/openvdb/openvdb/math/Coord.h b/openvdb/openvdb/math/Coord.h
@@ -224,8 +224,10 @@ class Coord
 
     /// @brief Return a hash value for this coordinate
     /// @note Log2N is the binary logarithm of the hash table size.
-    /// @details The hash function is taken from the SIGGRAPH paper:
+    /// @details The hash function is originally taken from the SIGGRAPH paper:
     /// "VDB: High-resolution sparse volumes with dynamic topology"
+    /// and the prime numbers are modified based on the ACM Transactions on Graphics paper:
+    /// "Real-time 3D reconstruction at scale using voxel hashing"
     template<int Log2N = 20>
     size_t hash() const
     {