RE: printing three display components

  • To: Tan Ka Ju <kaju@xxxxxxxxxxxxx>
  • Subject: RE: printing three display components
  • From: Tennessee James Leeuwenburg <tjl@xxxxxxxxxx>
  • Date: 28 Jul 2003 11:51:35 +1000
The following link is to the University of Melbourne's graphics course
loecture notes. You'll be able to find good descriptions of these kinds
of problems, and approaches of solving them here. Obviously though the
examples will be theoretical and not related to any particular language
so you'll have to find out the best way to do this in Java.

The buzzword I remember for this kind of thing is "bounding box".

http://www.cs.mu.oz.au/380/#lectureslides

Cheers,
-T

On Fri, 2003-07-25 at 21:05, Tan Ka Ju wrote:
> Thanks Bill for your reply. 
> 
> However, I currently only using Java-2D to generate graph (2D, planning
> to make into 3D after getting 2D done). I was trying to look for the
> algorithm, on how to detect a LINE if it is in a POLYGON, where the
> LINE's end and start points are given, and the POLYGON Area is obtained.
> The polygon is a tilted rectangle or a tilted pentagon. The angle of the
> tilted polygon is the same as the line.
> 
> I know this is really unrelated to VisAD. But I do hope if anyone of you
> did come across any articles or resources on this matter please kindly
> point me to it or guide me.
> 
> Thank you.
> Kj
> 
> Ps: Bill, even with the methods you mentioned, it can only detects a
> point. If this is the case, that means I need to run trough a loop for
> every point in the line in order for me to know if any part of the line
> is in a specified polygon. The problem is that I might need to check for
> hundreds or even thousands of lines (performance issue). Hence, I was
> looking for if there is any geometric or algorithm that can really save
> all of this looping, you know, by using some formula. Thanks.
> 
> 
> 
> 
> -----Original Message-----
> From: Bill Hibbard [mailto:billh@xxxxxxxxxxxxx] 
> Sent: Friday, July 25, 2003 5:35 PM
> To: Tan Ka Ju
> Cc: visad-list@xxxxxxxxxxxxx
> Subject: RE: printing three display components
> 
> If you are using VisAD, then the method:
> 
>   public static boolean inside(float[][] s, float x, float y)
> 
> in visad.DelaunayCustom will tell you if the point (x, y)
> is inside the polygon described by s, which is dimensioned
> float[2][number_of_points].
> 
> On Fri, 25 Jul 2003, Tan Ka Ju wrote:
> 
> > Hello.
> >
> > Is their in Java any method to know is a line contains or inside an
> > arbitrary polygon or shape? Or is the any algorithm or mathematics
> > formula that can solve this problem?
> >
> > Thanks.
> > KJ
> 
> 
> 
>