[vtkusers] PoinInPolygon arguments

[Jothybasu K Selvaraj]

Thanks, I understood.

Jothy

On Mon, Apr 12, 2010 at 12:31 PM, Eric E. Monson <emonson at cs.duke.edu>wrote:

> Hey Jothy,
>
> It is common in C++ to prepare space for an array of values, and then hand
> that array or variable to another method where it places the answer in that
> array.
>
> So, instead of doing something like
>
> n = ComputeNormal(...)
>
> He's just doing
>
> ComputeNormal(...,n);
>
> and the normal is getting placed into the three-value array "n" by the
> routine. Think of it as passing a bucket to the algorithm where it will
> place the answer.
>
> -Eric
>
> ------------------------------------------------------
> Eric E Monson
> Duke Visualization Technology Group
>
>
> On Apr 12, 2010, at 5:56 AM, Jothybasu K Selvaraj wrote:
>
> Hi David,
>
> I need a bit of clarification as I am not much familiar with c++.
>
>
> double n[3];* // you have declared the variable n*
>
>  polygon->ComputeNormal(
> polygon->GetPoints()->GetNumberOfPoints(),
> static_cast<double*>(polygon->GetPoints()->GetData()->GetVoidPointer(0)),
> *n);// How do you set this as an input to an argument as it doesn't hold
> any value*
>
> Did you mistyped or am I misinterpreted?
>
> Thanks,
>
> Jothy
>
>
>
>
> On Thu, Apr 8, 2010 at 12:43 AM, David Doria <daviddoria+vtk at gmail.com<daviddoria%2Bvtk at gmail.com>
> > wrote:
>
>> On Tue, Apr 6, 2010 at 11:33 AM, Bill Lorensen <bill.lorensen at gmail.com>
>> wrote:
>> > n is the normal to the face of the polygon
>> > numPts is the number of points in the polygon
>> > pts is an array of xyz points
>>
>>
>> The call was pretty nasty:
>>
>>
>>  double n[3];
>>  polygon->ComputeNormal(polygon->GetPoints()->GetNumberOfPoints(),
>> static_cast<double*>(polygon->GetPoints()->GetData()->GetVoidPointer(0)),
>> n);
>>
>>  double bounds[6];
>>  polygon->GetPoints()->GetBounds(bounds);
>>
>>  cout << "test x in polygon? " << polygon->PointInPolygon(x,
>> polygon->GetPoints()->GetNumberOfPoints(),
>> static_cast<double*>(polygon->GetPoints()->GetData()->GetVoidPointer(0)),
>> bounds, n) << endl;
>>
>> I just wrote a convenience function and submitted it to the developers
>> mailing list. If it is approved, in the future you can simply call
>>
>> cout << "test x in polygon? " << polygon->PointInPolygon(x) << endl;
>>
>> Thanks,
>>
>> David
>>
>
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