[vtkusers] Actor Disappeared

[Alex Malyushytskyy]

Even if somebody wanted to look at your code there is no way to
provide you any reliable advice cause you did not provide a compilable
example.
Simple examples:
 -  depending on the variable type you may or may not have problems in
various places.
 - sizeof also may produce a problem, if for example used with
dynamically allocated array.

Also I doubt you don't get memory leaks. For example
  tPoints = GenerateNewPoints(temp_para, count);
is called multiple times within  loop:
 while(abs(CurErr - PreErr) > threshold)
when only once
        tPoints->Delete();
is called

I would recommend you to get a debugger and check every line and
compare results with your expectations.

Regards,
   Alex


On Tue, Dec 6, 2011 at 2:58 PM, Wenlong Wang <scc.wwl at gmail.com> wrote:
> Dear all,
>
> I'm trying to do a gradient descent in my application. It was working well.
> But as I tried to lower the threshold(which means more iterations are
> happening), the application just stop rendering and give me a blank screen.
> Most misterious is, there is no error happens. No memory leak, no access
> vialation, no nothing. The program just jump out of the loop. I am really
> confused by this.
>
> Here is my code
>
> while(abs(CurErr - PreErr) > threshold)
>     {
>         PreErr = CurErr;
>         tPoints->Delete();
>
>         for (int i = 0; i<sizeof(para)/sizeof(double); i++)
>         {
>             temp_para[i] = para[i];
>         }
>
>         for(int index = 0; index < sizeof(para)/sizeof(double); index++)
>         {
>             temp_para[index] = temp_para[index] + temp_para[index]*step;
>
>
>             tCamera->DeepCopy(markCamera);
>             tPoints = GenerateNewPoints(temp_para, count);
>
>             double err = Dist_2DLandmarks(tPoints, tCamera);
>             temp_para[index] = para[index];
>             par_der[index] = (err - CurErr) / temp_para[index]*step;
>
>         }
>
>         for(int i = 0; i < sizeof(para)/sizeof(double); i++)
>         {
>             para[i] = para[i] - par_der[i] * step;
>         }
>
>         tPoints = GenerateNewPoints(para, count);
>
>         tCamera->DeepCopy(markCamera);
>
>         CurErr = Dist_2DLandmarks(tPoints, tCamera);
>         count ++;
>     }
>
> Thank you very much for any suggestions.
>
> Best regards
> Long
>
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