Greg M. Johnson wrote:
> 
> Why would the following code:
> 
>         #declare p0=MyTrack(nclock);
>         #declare p1=MyTrack(nclock+1/npoints);
>         #declare p2=MyTrack(nclock+2/npoints);
> 
>         #declare dr1=p1-p0;
>         #declare drx1=vnormalize(vcross(y+0.001,dr1));
> //this_is_line_76
>         #declare dry1=vnormalize(vcross(drx1-0.0001,dr1));
> //this_is_line_77
> 
> give me an error of:
> 
> File: C:\pov35\ini\sweep05.pov  Line: 76
> Error: Normalizing zero-length vector.
> File: C:\pov35\ini\sweep05.pov  Line: 77
> Error: Normalizing zero-length vector.

If dr1 = k*<.001,1.001,.001>, where k is any scalar value, the
cross product in line 76 will be <0,0,0>.

Since I don't know what the MyTrack macro does, I can't be fully
elucidating.

Regards,
John

Post a reply to this message