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<div class="title">Frequently Asked Questions </div> </div>
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<li>Q: <em>Why are the Python bindings not built?</em> <br/>
<b>Short answer (most likely case)</b>: after running <code>cmake</code>, type “<code>make update_bindings</code>”.<br/>
<b>Long answer</b>: the bindings are automatically generated by a script. You may not have all dependencies correctly installed (or detected by cmake). Check <a class="el" href="installation.html">Installation</a> and <a class="el" href="python.html#updating_python_bindings">(Re)generating the Python bindings</a> for details on installing dependencies and the individual steps involved in creating Python bindings, respectively.</li>
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<li>Q: <em>Why is the code I added to the OMPL source not being compiled?</em> <br/>
See <a class="el" href="buildSystem.html">Integrate your own code with OMPL's build system</a>. Essentially, just run <code>cmake</code> again after adding new files.</li>
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<li>Q: <em>How do I specify collision checking for a planner?</em> <br/>
A: See <a class="el" href="classompl_1_1base_1_1SpaceInformation.html#a0449ec0893e02aca2bdfc63323b624e5" title="Set the instance of the state validity checker to use. Parallel implementations of planners assume th...">ompl::base::SpaceInformation::setStateValidityChecker()</a> and <a class="el" href="classompl_1_1base_1_1StateValidityChecker.html" title="Abstract definition for a class checking the validity of states. The implementation of this class mus...">ompl::base::StateValidityChecker</a>.</li>
</ul>
<ul>
<li>Q: <em>Can I visualize the exploration datastructure used by a planner?</em> <br/>
A: Yes. You need to call <a class="el" href="classompl_1_1base_1_1Planner.html#afaaf08c87f8797803fbeb60771635ea5" title="Get information about the current run of the motion planner. Repeated calls to this function will upd...">ompl::base::Planner::getPlannerData()</a>. This will give you an instance of <a class="el" href="classompl_1_1base_1_1PlannerData.html" title="Datatype holding data a planner can expose for debug purposes.">ompl::base::PlannerData</a> which contains all the states and the edges between them. Functionality for plotting this data is however not available.</li>
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<ul>
<li>Q: <em>Can I change the state space during planning?</em> <br/>
A: No. Such changes will make the code crash.</li>
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<li>Q: <em>Can I set the sampler to use for a planner?</em> <br/>
A: Yes. The sampler instances used by planners are allocated by either <a class="el" href="classompl_1_1base_1_1SpaceInformation.html#a65ba2c60529f5aa23098d43c6c2b6da4" title="Allocate a uniform state sampler for the state space.">ompl::base::SpaceInformation::allocStateSampler()</a> (which calls <a class="el" href="classompl_1_1base_1_1StateSpace.html#a345d227779a17370264430aa2958c055" title="Allocate an instance of a uniform state sampler for this space.">ompl::base::StateSpace::allocStateSampler()</a> under the hood) or by <a class="el" href="classompl_1_1base_1_1SpaceInformation.html#acb94231d22c1763e3f79e5d67e5e7428" title="Allocate an instance of a valid state sampler for this space. If setValidStateSamplerAllocator() was ...">ompl::base::SpaceInformation::allocValidStateSampler()</a>. By default, <a class="el" href="classompl_1_1base_1_1SpaceInformation.html#acb94231d22c1763e3f79e5d67e5e7428" title="Allocate an instance of a valid state sampler for this space. If setValidStateSamplerAllocator() was ...">ompl::base::SpaceInformation::allocValidStateSampler()</a> produces an instance of <a class="el" href="classompl_1_1base_1_1UniformValidStateSampler.html" title="A state sampler that only samples valid states, uniformly.">ompl::base::UniformValidStateSampler</a>, unless a sampler allocator was specified. Calling <a class="el" href="classompl_1_1base_1_1SpaceInformation.html#ae6391771fc74984a3266f986cfe07780" title="Set the allocator to use for a valid state sampler. This replaces the default uniform valid state sam...">ompl::base::SpaceInformation::setValidStateSamplerAllocator()</a> allows the user to specify the valid state sampler allocator, thus changing the sampling strategy used by planners. <div class="fragment"><pre class="fragment"><span class="preprocessor"> #include "ompl/base/samplers/ObstacleBasedValidStateSampler.h"</span>
...
<a class="code" href="classompl_1_1base_1_1ValidStateSamplerPtr.html" title="A boost shared pointer wrapper for ompl::base::ValidStateSampler.">ompl::base::ValidStateSamplerPtr</a> allocValidStateSampler(<span class="keyword">const</span> <a class="code" href="classompl_1_1base_1_1SpaceInformation.html" title="The base class for space information. This contains all the information about the space planning is d...">ompl::base::SpaceInformation</a> *si)
{
<span class="keywordflow">return</span> <a class="code" href="classompl_1_1base_1_1ValidStateSamplerPtr.html" title="A boost shared pointer wrapper for ompl::base::ValidStateSampler.">ompl::base::ValidStateSamplerPtr</a>(<span class="keyword">new</span> <a class="code" href="classompl_1_1base_1_1ObstacleBasedValidStateSampler.html" title="Generate valid samples using the Bridge Test.">ompl::base::ObstacleBasedValidStateSampler</a>(si));
}
...
<a class="code" href="classompl_1_1base_1_1StateSpacePtr.html" title="A boost shared pointer wrapper for ompl::base::StateSpace.">ompl::base::StateSpacePtr</a> space(...);
<a class="code" href="classompl_1_1base_1_1SpaceInformationPtr.html" title="A boost shared pointer wrapper for ompl::base::SpaceInformation.">ompl::base::SpaceInformationPtr</a> si(<span class="keyword">new</span> <a class="code" href="classompl_1_1base_1_1SpaceInformation.html" title="The base class for space information. This contains all the information about the space planning is d...">ompl::base::SpaceInformation</a>(space));
si-><a class="code" href="classompl_1_1base_1_1SpaceInformation.html#ae6391771fc74984a3266f986cfe07780" title="Set the allocator to use for a valid state sampler. This replaces the default uniform valid state sam...">setValidStateSamplerAllocator</a>(boost::bind(&allocValidStateSampler, _1));
<span class="comment">// for simplified calls, you can also use:</span>
<span class="comment">// si->setValidStateSamplerAllocator(&allocValidStateSampler);</span>
</pre></div></li>
</ul>
<p><br/>
If your question is still not answered, another good place to check is the <a href="http://sourceforge.net/mailarchive/forum.php?forum_name=ompl-users">mailing list archive</a>. </p>
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