Re: Compare TGeoShape

Hi Jason,

I fully agree that this can be done, but finally why would you need such a check ? The idea in geometry is to replicate whatever you can rather that create shapes with exactly same parameters. If you follow this , the comparison is just a trivial pointer comparison...

Cheers,
Andrei

On 07/15/2010 05:10 PM, Jason Webb wrote:
> Hi Andrei,
>
> Thanks for the reply. I will proceed with my (ugly, error prone,
> difficult to maintain) work around.
>
> However, I think that you are overestimating the effort it would take to
> implement this functionality. If TGeoShape stored a dynamic array of
> parameters then the equality method becomes trivial. Just loop over the
> two arrays and check equality of elements.
>
> Such an array could be created and filled with modest effort. 20 shapes,
> averaging 10 parameters per shape. To store these parameters would take
> approximately 20 x 10 = 200 lines of code. Double for overhead, 400
> lines of code. (pcon and pgon being exceptions, but easily handled).
>
> Composite shapes should also be easy to handle. Check that the
> expressions are the same, and if so, check that each of the named shapes
> are equal.
>
> Cheers,
> Jason
>
> Andrei Gheata wrote:
>> Hi Jason,
>>
>> This comparison is not implemented and not in the plan. The reason is
>> that there are ~20 different shapes and this makes the implementation
>> effort too big and not scaling with the limited use cases. Besides,
>> this cannot be implemented for Boolean composite shapes that can be of
>> infinite variety.
>>
>> Best,
>> Andrei
>>
>> On 07/14/2010 11:03 PM, Jason Webb wrote:
>>> Hi ROOTers,
>>>
>>> Is there a simple way to compare two TGeoShapes to each other?
>>> Specifically I am interested in functionality like
>>>
>>> TGeoShape *shape1 = ...
>>> TGeoShape *shape2 = ...
>>>
>>> if ( shape1->IsEqualTo(shape2) )
>>> {
>>> std::cout << "same"<<std::endl;
>>> }
>>>
>>> where shape1 and shape2 are any of the TGeo shapes, and the 'IsEqualTo'
>>> function would return true if they are of the same class and have the
>>> same parameters.
>>>
>>> Thanks,
>>> Jason
>>>
>
Received on Thu Jul 15 2010 - 18:19:24 CEST