Cannot go under a bridge-like mesh

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robee00
Posts: 3
Joined: Wed Feb 26, 2014 6:23 pm

Cannot go under a bridge-like mesh

Post by robee00 »

Hi!

I started using Bullet, and in my project, I load an obj file, which looks like a stone bridge. I create a TriangleMeshShape from it, it has a mass of 0, so it's static. When I want to go under it with a CapsuleShape, I can't. I looks like they are colliding, but they are not. I made sure that the capsule is small enough to go under the bridge, but I just cannot go. The mesh looks like this: http://i.imgur.com/Hmwfp.png

Thanks!
bwelch
Posts: 48
Joined: Thu Dec 12, 2013 4:04 pm

Re: Cannot go under a bridge-like mesh

Post by bwelch »

Not sure if any of this will help you, but they're the first things that came to mind when I read your post.
-Is the mesh you're importing only the brown arch part? Could the ground be getting added, too, which might be causing your collisions?
-Have you tried dropping the mesh into one of the Bullet Demos so you can visualize the collision geometry? I have to do this sometimes with the project I'm working on since Bullet objects are invisible in my display program. It might help you figure out what's going on.
-Check to see that Bullet's X, Y, and Z correspond to any other coordinate systems you're using. In my project, Bullet's Y axis is my display's Z axis, so I have to flip everything. Maybe your model is turned on its side?

Hope you get your issue solved!
robee00
Posts: 3
Joined: Wed Feb 26, 2014 6:23 pm

Re: Cannot go under a bridge-like mesh

Post by robee00 »

I dropped in a GLDebugDrawer so I can visualize my model's collision geometry.
Yes, only the brown part is imported, and I think the coordinate system is okay, as my mesh looks normal.
robee00
Posts: 3
Joined: Wed Feb 26, 2014 6:23 pm

Re: Cannot go under a bridge-like mesh

Post by robee00 »

I dropped in the mesh to Unity, and used a capsule collider with the same parameters in unity, and can go under the mesh. The mesh collider is the same in unity.
Systemtechniker
Posts: 1
Joined: Wed Jul 21, 2021 8:51 pm

Re: Cannot go under a bridge-like mesh

Post by Systemtechniker »

I have the same problem with a pipe that should encompass other objects, but it acts as a solid cylinder in the simulation. Here the URDF:

The mesh looks like this: Image

Code: Select all

<robot
  name="PlayPenURDF">
  <link
    name="Body">
    <inertial>
      <origin
        xyz="-5.55111512312578E-17 -0.00480014107726523 0"
        rpy="0 0 0" />
      <mass
        value="13.9758586349204" />
      <inertia
        ixx="1.74953594219083"
        ixy="-2.36355193514317E-17"
        ixz="3.70074341541718E-16"
        iyy="3.4790390640101"
        iyz="-1.31174746495725E-18"
        izz="1.74953594219083" />
    </inertial>
    <visual>
      <origin
        xyz="0 0 0"
        rpy="0 0 0" />
      <geometry>
        <mesh
          filename="package://PlayPenURDF/meshes/Body.STL" />
      </geometry>
      <material
        name="">
        <color
          rgba="0.752941176470588 0.752941176470588 0.752941176470588 1" />
      </material>
    </visual>
    <collision>
      <origin
        xyz="0 0 0"
        rpy="0 0 0" />
      <geometry>
        <mesh
          filename="package://PlayPenURDF/meshes/Body.STL" />
      </geometry>
    </collision>
  </link>
</robot>
Any help is appreciated.
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