From 96e8dcef0f57c730ea1f268d6cd575dac22f5d7e Mon Sep 17 00:00:00 2001
From: Xuchen Han <xuchenhan@xuchenhan-macbookpro.roam.corp.google.com>
Date: Thu, 8 Aug 2019 16:45:19 -0700
Subject: fix bug caused by not reseting to zero

---
 src/BulletSoftBody/btDeformableBodySolver.cpp | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/BulletSoftBody/btDeformableBodySolver.cpp b/src/BulletSoftBody/btDeformableBodySolver.cpp
index fc792bd7f..4dd45edc8 100644
--- a/src/BulletSoftBody/btDeformableBodySolver.cpp
+++ b/src/BulletSoftBody/btDeformableBodySolver.cpp
@@ -55,9 +55,19 @@ void btDeformableBodySolver::reinitialize(const btAlignedObjectArray<btSoftBody
     m_softBodySet.copyFromArray(softBodies);
     bool nodeUpdated = updateNodes();
     
-    m_dv.resize(m_numNodes, btVector3(0,0,0));
-    m_residual.resize(m_numNodes, btVector3(0,0,0));
-    m_backupVelocity.resize(m_numNodes, btVector3(0,0,0));
+    if (nodeUpdated)
+    {
+        m_dv.resize(m_numNodes, btVector3(0,0,0));
+        m_residual.resize(m_numNodes, btVector3(0,0,0));
+        m_backupVelocity.resize(m_numNodes, btVector3(0,0,0));
+    }
+    
+    // need to setZero here as resize only set value for newly allocated items
+    for (int i = 0; i < m_numNodes; ++i)
+    {
+        m_dv[i].setZero();
+        m_residual[i].setZero();
+    }
     
     m_objective->reinitialize(nodeUpdated);
 }
-- 
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