only call buildIslands once for multibody in each timestep

src/BulletSoftBody/btDeformableBackwardEulerObjective.cpp

@@ -128,3 +128,11 @@ void btDeformableBackwardEulerObjective::initialGuess(TVStack& dv, const TVStack
         }
     }
 }
+
+//set constraints as projections
+void btDeformableBackwardEulerObjective::setConstraints()
+{
+    // build islands for multibody solve
+    m_world->btMultiBodyDynamicsWorld::buildIslands();
+    projection.setConstraints();
+}

src/BulletSoftBody/btDeformableBackwardEulerObjective.h

@@ -73,10 +73,7 @@ public:
     void updateVelocity(const TVStack& dv);
     
     //set constraints as projections
-    void setConstraints()
-    {
-        projection.setConstraints();
-    }
+    void setConstraints();
     
     // update the projections and project the residual
     void project(TVStack& r)

src/BulletSoftBody/btDeformableBodySolver.cpp

@@ -31,7 +31,7 @@ void btDeformableBodySolver::solveConstraints(float solverdt)
     backupVelocity();
     
     m_objective->computeResidual(solverdt, m_residual);
-//   m_objective->initialGuess(m_dv, m_residual);
+    
     computeStep(m_dv, m_residual);
     updateVelocity();
 }