<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hey Jothy,<div><br></div><div>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. </div><div><br></div><div>So, instead of doing something like </div><div><br></div><div>n = ComputeNormal(...)</div><div><br></div><div>He's just doing </div><div><br></div><div>ComputeNormal(...,n);</div><div><br></div><div>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.</div><div><br></div><div>-Eric</div><div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; ">------------------------------------------------------<br>Eric E Monson<br>Duke Visualization Technology Group<br></span>
</div>
<div><br></div><br><div><div>On Apr 12, 2010, at 5:56 AM, Jothybasu K Selvaraj wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr">Hi David,<br><br>I need a bit of clarification as I am not much familiar with c++.<br><br><br>double n[3];<b><span style="color: rgb(255, 0, 0);"> // you have declared the variable n</span></b><br><br>
polygon->ComputeNormal(<div id=":ss" class="ii gt">polygon->GetPoints()->GetNumberOfPoints(),<br>
static_cast<double*>(polygon->GetPoints()->GetData()->GetVoidPointer(0)),<br>
<b><span style="color: rgb(255, 0, 0);">n);// How do you set this as an input to an argument as it doesn't hold any value</span></b><br><br>Did you mistyped or am I misinterpreted?<br><br>Thanks,<br><br>Jothy<br><br>
<br></div><br><br><div class="gmail_quote">On Thu, Apr 8, 2010 at 12:43 AM, David Doria <span dir="ltr"><<a href="mailto:daviddoria%2Bvtk@gmail.com">daviddoria+vtk@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div class="im">On Tue, Apr 6, 2010 at 11:33 AM, Bill Lorensen <<a href="mailto:bill.lorensen@gmail.com">bill.lorensen@gmail.com</a>> wrote:<br>
> n is the normal to the face of the polygon<br>
> numPts is the number of points in the polygon<br>
> pts is an array of xyz points<br>
<br>
<br>
</div>The call was pretty nasty:<br>
<br>
<br>
double n[3];<br>
polygon->ComputeNormal(polygon->GetPoints()->GetNumberOfPoints(),<br>
static_cast<double*>(polygon->GetPoints()->GetData()->GetVoidPointer(0)),<br>
n);<br>
<br>
double bounds[6];<br>
polygon->GetPoints()->GetBounds(bounds);<br>
<br>
cout << "test x in polygon? " << polygon->PointInPolygon(x,<br>
polygon->GetPoints()->GetNumberOfPoints(),<br>
static_cast<double*>(polygon->GetPoints()->GetData()->GetVoidPointer(0)),<br>
bounds, n) << endl;<br>
<br>
I just wrote a convenience function and submitted it to the developers<br>
mailing list. If it is approved, in the future you can simply call<br>
<br>
cout << "test x in polygon? " << polygon->PointInPolygon(x) << endl;<br>
<br>
Thanks,<br>
<font color="#888888"><br>
David<br>
</font></blockquote></div><br></div>
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