Unity uses a left-handed, y-up system, which is different with the common right-handed system in a lot of libraries for robotics.
We provide the functions for converting Unity frame to PyBullet frame in PoseUtils
PoseUtils converts the position, rotation (euler angle), and scale between Unity and PyBullet.
Run pose_convert.py on Python side:
unity_pos = [0.52, 2.28, 0.75]
unity_qua = [0, 0.258819103, 0, 0.965925813]
unity_euler = [0, 30, 0]
unity_sca = [1., 2., 1.5]
id_simulator = p.connect(p.GUI)
p.setTimeStep(0.02)
pose = PoseUtils()
box = p.createVisualShape(shapeType=p.GEOM_BOX, halfExtents=pose.unity_scale_to_bullet_scale((np.array(unity_sca) / 2).tolist()))
p.createMultiBody(baseVisualShapeIndex=box, basePosition=pose.unity_pos_to_bullet_pos(unity_pos), baseOrientation=pose.unity_qua_to_bullet_qua(unity_qua))
while 1:
p.stepSimulation(id_simulator)
time.sleep(0.02)
On Unity, open pose_utils scene. There is a cube with unity_pos , unity_euler , and unity_sca . This python script will convert the pose in unity to pybullet, and render a box with the same properties.
| Function | Description |
|---|---|
| bullet_pos_to_unity_pos | Convert bullet position to unity position |
| unity_pos_to_bullet_pos | Convert unity position to bullet position |
| bullet_qua_to_unity_qua | Convert bullet quartenion to unity quaternion |
| unity_qua_to_bullet_qua | Convert unity quaternion to bullet quaternion |
| bullet_sca_to_unity_sca | Convert bullet scale to unity scale |
| unity_sca_to_bullet_sca | Convert unity scale to bullet scale |
from pyrcareworld.utils import PoseUtils
env = RCareWorld()
pose_convert = PoseUtils()
my_unity_pose = pose_convert.bullet_pos_to_unity_pos([0, 0, 1])
<aside> 💡 Coordinate system and rotation can be different in different simulation platforms, and can be confusing but very important. To get a better understanding of Unity’s rotation, check
Unity Quaternion and Rotation Guide for beginners - VionixStudio
</aside>