enable planar reflection in MinitaurGymEnv

enable follow cam in other Gym locomotion environments
add testing assets for multi-material obj files -> sdf conversion.
Also use ER_NO_SEGMENTATION_MASK flag for TinyRenderer/EGL plugin renderer

examples/pybullet/gym/pybullet_envs/env_bases.py

@@ -111,6 +111,16 @@ class MJCFBaseBulletEnv(gym.Env):
 	# backwards compatibility for gym >= v0.9.x
 	# for extension of this class.
 	def step(self, *args, **kwargs):
+		if self.isRender:
+			base_pos=[0,0,0]
+			if (hasattr(self,'robot')):
+				if (hasattr(self.robot,'body_xyz')):
+					base_pos = self.robot.body_xyz
+					# Keep the previous orientation of the camera set by the user.
+					#[yaw, pitch, dist] = self._p.getDebugVisualizerCamera()[8:11]
+					self._p.resetDebugVisualizerCamera(3,0,0, base_pos)
+
+
 		return self._step(*args, **kwargs)
 
 	if parse_version(gym.__version__)>=parse_version('0.9.6'):

examples/pybullet/gym/pybullet_envs/minitaur/envs/minitaur_gym_env.py

@@ -271,7 +271,7 @@ class MinitaurGymEnv(gym.Env):
           "%s/plane.urdf" % self._urdf_root)
       if (self._reflection):
         self._pybullet_client.changeVisualShape(self._ground_id,-1,rgbaColor=[1,1,1,0.8])
-        #self._pybullet_client.configureDebugVisualizer(self._pybullet_client.COV_ENABLE_PLANAR_REFLECTION,1)
+        self._pybullet_client.configureDebugVisualizer(self._pybullet_client.COV_ENABLE_PLANAR_REFLECTION,self._ground_id)
       self._pybullet_client.setGravity(0, 0, -10)
       acc_motor = self._accurate_motor_model_enabled
       motor_protect = self._motor_overheat_protection