RE: [OpenMap Users] Clipping "lines"

From: Chapman, Martin <>
Date: Tue, 21 Sep 2004 15:47:38 -0600

Your problem is that you're zooming in so close that you are splitting
pixels. I had the same problem. The solution is to limit how far you
can zoom in. Once you're at the pixel level the map is invalid if
zoomed in any farther anyway.

        -----Original Message-----
        From: Andrew Hnatiw []
        Sent: Tuesday, September 21, 2004 2:41 PM
        To: ''
        Subject: [OpenMap Users] Clipping "lines"

        I am having program crashes due to zooming in very far and
having things drawn way off the screen, resulting in either tons of
these weird java PRExceptions, or just a sudden exit by the program.
>From what I've read online on old parts of the mailing list for openmap
and on the Sun website, this is just one of those problems with the java
graphics api - it throws these exceptions when you have graphics far
away from the viewable screen. The main thing that causes the problem
in my application is drawing lines that are partially on the screen, but
then stretch far off when I am zoomed in very close. The only solution
I could come up with is clipping the lines. Does anybody have any
advice on how to do this? My lines are not rhumb lines, they are lines
along the great circles, and I was hoping to get this to work for
multiple projection types. My plan is to calculate the equation of the
arc of the great circle that contains the "line", and then find where it
intersects a bounding box denoted by lats and lons.
        So now to the question - Is there any way to get OpenMap to do
this all for me? I have some messy equations using vector math, and I'm
thinking of using the javax.vecmath package that comes with java 3d.
any better ideas... this way seems really math intensive and probably
slow... and I'm not even sure if this will solve the problem - has
anybody else dealt with this problem?
        Andrew Hnatiw

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Received on Tue Sep 21 2004 - 17:48:35 EDT

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