From db0127859aeb27add83afc9440f41e1a0a8db6db Mon Sep 17 00:00:00 2001
From: Malcolm Tyrrell <matyrr@microsoft.com>
Date: Thu, 21 Oct 2021 08:39:44 +0100
Subject: [PATCH] CalculateDistance method

---
 code/Common/SpatialSort.cpp        | 11 ++++++++---
 include/assimp/SpatialSort.h       | 17 ++++++++++++-----
 test/unit/Common/utSpatialSort.cpp |  2 +-
 3 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/code/Common/SpatialSort.cpp b/code/Common/SpatialSort.cpp
index 08a7c55df..9b96887ac 100644
--- a/code/Common/SpatialSort.cpp
+++ b/code/Common/SpatialSort.cpp
@@ -87,6 +87,11 @@ void SpatialSort::Fill(const aiVector3D *pPositions, unsigned int pNumPositions,
     mFinalized = pFinalize;
 }
 
+// ------------------------------------------------------------------------------------------------
+ai_real SpatialSort::CalculateDistance(const aiVector3D &pPosition) const {
+    return (pPosition - mCentroid) * mPlaneNormal;
+}
+
 // ------------------------------------------------------------------------------------------------
 void SpatialSort::Finalize() {
     const ai_real scale = 1.0f / mPositions.size();
@@ -94,7 +99,7 @@ void SpatialSort::Finalize() {
         mCentroid += scale * mPositions[i].mPosition; 
     }
     for (unsigned int i = 0; i < mPositions.size(); i++) {
-        mPositions[i].mDistance = (mPositions[i].mPosition - mCentroid) * mPlaneNormal;
+        mPositions[i].mDistance = CalculateDistance(mPositions[i].mPosition);
     }
     std::sort(mPositions.begin(), mPositions.end());
     mFinalized = true;
@@ -125,7 +130,7 @@ void SpatialSort::Append(const aiVector3D *pPositions, unsigned int pNumPosition
 void SpatialSort::FindPositions(const aiVector3D &pPosition,
         ai_real pRadius, std::vector<unsigned int> &poResults) const {
     ai_assert(mFinalized && "The SpatialSort object must be finalized before FindPositions can be called.");
-    const ai_real dist = (pPosition - mCentroid) * mPlaneNormal;
+    const ai_real dist = CalculateDistance(pPosition);
     const ai_real minDist = dist - pRadius, maxDist = dist + pRadius;
 
     // clear the array
@@ -266,7 +271,7 @@ void SpatialSort::FindIdenticalPositions(const aiVector3D &pPosition, std::vecto
 
     // Convert the plane distance to its signed integer representation so the ULPs tolerance can be
     //  applied. For some reason, VC won't optimize two calls of the bit pattern conversion.
-    const BinFloat minDistBinary = ToBinary((pPosition - mCentroid) * mPlaneNormal) - distanceToleranceInULPs;
+    const BinFloat minDistBinary = ToBinary(CalculateDistance(pPosition)) - distanceToleranceInULPs;
     const BinFloat maxDistBinary = minDistBinary + 2 * distanceToleranceInULPs;
 
     // clear the array in this strange fashion because a simple clear() would also deallocate
diff --git a/include/assimp/SpatialSort.h b/include/assimp/SpatialSort.h
index 39f863b15..c0c4a0292 100644
--- a/include/assimp/SpatialSort.h
+++ b/include/assimp/SpatialSort.h
@@ -143,9 +143,19 @@ public:
             ai_real pRadius) const;
 
 protected:
-    /** Normal of the sorting plane, normalized. */
+    /** Return the distance to the sorting plane. */
+    ai_real CalculateDistance(const aiVector3D &pPosition) const;
+
+protected:
+    /** Normal of the sorting plane, normalized.
+     */
     aiVector3D mPlaneNormal;
 
+    /** The centroid of the positions, which is used as a point on the sorting plane
+     * when calculating distance. This value is calculated in Finalize.
+    */
+    aiVector3D mCentroid;
+
     /** An entry in a spatially sorted position array. Consists of a vertex index,
      * its position and its pre-calculated distance from the reference plane */
     struct Entry {
@@ -161,7 +171,7 @@ protected:
             // empty
         }
         Entry(unsigned int pIndex, const aiVector3D &pPosition) :
-                mIndex(pIndex), mPosition(pPosition) {
+                mIndex(pIndex), mPosition(pPosition), mDistance(std::numeric_limits<ai_real>::max()) {
             // empty
         }
 
@@ -173,9 +183,6 @@ protected:
 
     /// false until the Finalize method is called.
     bool mFinalized;
-
-    /// The centroid of the positions. Calculated in Finalize.
-    aiVector3D mCentroid;
 };
 
 } // end of namespace Assimp
diff --git a/test/unit/Common/utSpatialSort.cpp b/test/unit/Common/utSpatialSort.cpp
index 8ebae76e8..f0b694c7d 100644
--- a/test/unit/Common/utSpatialSort.cpp
+++ b/test/unit/Common/utSpatialSort.cpp
@@ -103,7 +103,7 @@ TEST_F(utSpatialSort, highlyDisplacedPositionsTest) {
     SpatialSort sSort;
     sSort.Fill(positions, totalNumPositions, sizeof(aiVector3D));
 
-    // Enough to pick up a point and its 6 immediate neighbors, but not any other point.
+    // Enough to find a point and its 6 immediate neighbors, but not any other point.
     const ai_real epsilon = 1.1f * step;
     std::vector<unsigned int> indices;
     // Iterate through the _interior_ points of the cube.