Constraint Ball Joint

[Musa Audu]

In the C++ code of ExampleClosedTopologyMechanism of Simbody, a ball constraint was defined using the form: "Constraint::Ball(linker1, Vec3(linkerHalfDims[0],0,0), rocker1, Vec3(0,-rockerHalfDims[1],0));" When I used the same form in my code as: SimTK::Constraint::Ball(parent_body, loc_p, child_body, loc_c); results in error: "Incomplete type is not allowed". Could anyone explain to me why it works in that scenario and not in my case? Thanks.
Musa

[Michael Sherman]

An incomplete type error can arise from a missing header file in the complaining compilation unit. It would likely help also to know which of the many objects in that statement the compiler is complaining about.

[Dimitar Stanev]

Hi,

It is possible that you provided the Body instances to the Ball constraint. The first argument to the constraint is a MobilizedBody object.

Code: Select all

Ball (MobilizedBody &parent, const Transform &X_PF, const Body &bodyInfo, const Transform &X_BM, Direction=Forward)

Regards