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PostPosted: Wed Aug 09, 2017 9:36 am 
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Joined: Fri Aug 04, 2017 5:10 am
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I try to implement the ant usecase (http://www.bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=9&t=11818), which was originally based on rigid bodies.

As simple example, suppose to have a spehre, and a capsule shape (leg) horicontally pointing away from the sphere (aligned along the x-axis)
I create the shape (which is initially aligned along Y per construction), form the multibody, add the revolute constraint, create the collision shape, rotate is. (following e.g. the example https://github.com/bulletphysics/bullet3/blob/master/examples/MultiBody/InvertedPendulumPDControl.cpp).

My problem is now, that initially (before executing any stepSimulation), everything looks as expected (the leg oricontally).
But right after the 1st timestep, the leg is aligned along the y-axis - like the original shape right after creation, before rotation.
The revolute in principle works well (it acts on the COM); only the shape is displayed rotated (around the COM) from alongx to along-y.

The examples circumvent this problem, as they use boxes which can be created with the long side along x instead along y in the corresponding examples (e.g. constraint feedback, where the pendulum is oriented horicontally).

For the capsule shape, I could not find a possibility to create it such, that is aling with the long side along x - how to do that?

Alex


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