From a4074eaf26d64be11d8f60b5a12d2fd0b84d783e Mon Sep 17 00:00:00 2001
From: krickw <william.krick@autodesk.com>
Date: Wed, 10 Jun 2020 13:58:33 -0400
Subject: [PATCH 1/2] Remove duplicate instance indices.

---
 .../render/vp2RenderDelegate/basisCurves.cpp  | 21 ++++++++++++++++++
 lib/mayaUsd/render/vp2RenderDelegate/mesh.cpp | 22 +++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/lib/mayaUsd/render/vp2RenderDelegate/basisCurves.cpp b/lib/mayaUsd/render/vp2RenderDelegate/basisCurves.cpp
index 8eb83e5f47..126c610bf9 100644
--- a/lib/mayaUsd/render/vp2RenderDelegate/basisCurves.cpp
+++ b/lib/mayaUsd/render/vp2RenderDelegate/basisCurves.cpp
@@ -1101,6 +1101,26 @@ HdVP2BasisCurves::_UpdateDrawItem(
                 }
             }
             else if (auto state = drawScene.GetPrimSelectionState(id)) {
+#if USD_VERSION_NUM <= 2005
+                // In 20.05 and older GetPrimSelectionState may have duplicate entries
+                // in instanceIndices, which will cause Maya to draw that instance multiple
+                // times. Remove the duplicates here to avoid that problem.
+                std::vector<bool> selectedIndices;
+                selectedIndices.resize(instanceCount); // bool default ctor sets the value to false
+                for (const auto& indexArray : state->instanceIndices) {   
+                    for (const auto index : indexArray) {
+                        selectedIndices[index] = true;
+                    }
+                }
+                for (unsigned int index=0; index<instanceCount; index++)
+                {
+                    if (!selectedIndices[index])
+                        continue;
+                    transforms[index].Get(instanceMatrix.matrix);
+                    instanceMatrix = worldMatrix * instanceMatrix;
+                    stateToCommit._instanceTransforms.append(instanceMatrix);
+                }
+#else
                 for (const auto& indexArray : state->instanceIndices) {
                     for (const auto index : indexArray) {
                         transforms[index].Get(instanceMatrix.matrix);
@@ -1108,6 +1128,7 @@ HdVP2BasisCurves::_UpdateDrawItem(
                         stateToCommit._instanceTransforms.append(instanceMatrix);
                     }
                 }
+#endif
             }
         }
         else {
diff --git a/lib/mayaUsd/render/vp2RenderDelegate/mesh.cpp b/lib/mayaUsd/render/vp2RenderDelegate/mesh.cpp
index 29fd2430ef..0e8485fa5d 100644
--- a/lib/mayaUsd/render/vp2RenderDelegate/mesh.cpp
+++ b/lib/mayaUsd/render/vp2RenderDelegate/mesh.cpp
@@ -16,6 +16,7 @@
 #include "mesh.h"
 
 #include <numeric>
+#include <unordered_set>
 
 #include <maya/MMatrix.h>
 #include <maya/MProfiler.h>
@@ -1293,6 +1294,26 @@ void HdVP2Mesh::_UpdateDrawItem(
                 }
             }
             else if (auto state = drawScene.GetPrimSelectionState(id)) {
+#if USD_VERSION_NUM <= 2005
+                // In 20.05 and older GetPrimSelectionState may have duplicate entries
+                // in instanceIndices, which will cause Maya to draw that instance multiple
+                // times. Remove the duplicates here to avoid that problem.
+                std::vector<bool> selectedIndices;
+                selectedIndices.resize(instanceCount); // bool default ctor sets the value to false
+                for (const auto& indexArray : state->instanceIndices) {   
+                    for (const auto index : indexArray) {
+                        selectedIndices[index] = true;
+                    }
+                }
+                for (unsigned int index=0; index<instanceCount; index++)
+                {
+                    if (!selectedIndices[index])
+                        continue;
+                    transforms[index].Get(instanceMatrix.matrix);
+                    instanceMatrix = worldMatrix * instanceMatrix;
+                    stateToCommit._instanceTransforms.append(instanceMatrix);
+                }
+#else
                 for (const auto& indexArray : state->instanceIndices) {
                     for (const auto index : indexArray) {
                         transforms[index].Get(instanceMatrix.matrix);
@@ -1300,6 +1321,7 @@ void HdVP2Mesh::_UpdateDrawItem(
                         stateToCommit._instanceTransforms.append(instanceMatrix);
                     }
                 }
+#endif
             }
         }
         else {

From ba7666d2146b49584b48462c4f5132d0a4c3895d Mon Sep 17 00:00:00 2001
From: krickw <william.krick@autodesk.com>
Date: Wed, 10 Jun 2020 15:47:53 -0400
Subject: [PATCH 2/2] Remove unused header.

---
 lib/mayaUsd/render/vp2RenderDelegate/mesh.cpp | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/mayaUsd/render/vp2RenderDelegate/mesh.cpp b/lib/mayaUsd/render/vp2RenderDelegate/mesh.cpp
index 0e8485fa5d..7dd7ecc846 100644
--- a/lib/mayaUsd/render/vp2RenderDelegate/mesh.cpp
+++ b/lib/mayaUsd/render/vp2RenderDelegate/mesh.cpp
@@ -16,7 +16,6 @@
 #include "mesh.h"
 
 #include <numeric>
-#include <unordered_set>
 
 #include <maya/MMatrix.h>
 #include <maya/MProfiler.h>