Fix SampleConsensusModel constructor to not use a virtual function

[jmackay2]

Calling virtual functions from a constructor is considered dangerous. This removes the call of the virtual function setInputCloud by setting the indices. This also simplifies some of the duplicate code in the constructors.

[mvieth]

Sorry for the delay!
Maybe a dumb question, but what is the possible danger with calling setInputCloud from the constructor here?

[mvieth]

Could adding a default value for indices not create a possible ambiguity if only the cloud parameter is given? Then there would not be a way to distinguish between this ctor and SampleConsensusModel (const PointCloudConstPtr &cloud, const bool random = false), right?

[jmackay2]

Yes, this is definitely ambiguous. This has been fixed by removing the default for indices.

[jmackay2]

Sorry for the delay! Maybe a dumb question, but what is the possible danger with calling setInputCloud from the constructor here?

From my understanding, the danger is that setInputCloud is a virtual function for this class, which means it may not be available in the constructor since the SampleConsensusModel object has not been created yet. This means it is likely or possible to call the base function instead of the virtual function in this class.

[mvieth]

I still do not see the specific danger in this case since SampleConsensusModel does not have a parent class, so as far as I can see, the only version of setInputCloud that could be called from the constructor is the one in SampleConsensusModel (as one would expect). But I guess following the general rule to not call a virtual function from a constructor is still a good idea. Thanks!