PyBullet: handle the switch from fixed base to floating base when changing mass from zero to non-zero

examples/pybullet/examples/changeDynamicsMass.py

@@ -0,0 +1,15 @@
+import pybullet as p
+import time
+
+p.connect(p.GUI)
+cube2 = p.loadURDF("cube.urdf",[0,0,3], useFixedBase=True)
+cube = p.loadURDF("cube.urdf", useFixedBase=True)
+p.setGravity(0,0,-10)
+timeStep = 1./240.
+p.setTimeStep(timeStep)
+p.changeDynamics(cube2,-1,mass=1)
+#now cube2 will have a floating base and move
+
+while (p.isConnected()):
+	p.stepSimulation()
+	time.sleep(timeStep)