Re: Clipping of polygons partially outside hemisphere

Hi Karen,

I'd check to see what the projection is returning for the getUpperLeft()
and getLowerRight() methods. These methods are used by some layers to
figure out what graphics to place on the map. With some projections,
you don't actually want to return the inverse projection of (0, 0) and
(width, height). The getUpperLeft() method should return the minimum
longitude of the left side of the window and the maximum latitude of the
top of the window. Likewise, the getLowerRight() method should return
the maximum longitude of the right side of the window and the smallest
latitude of the bottom of the window.

You can do a quick check for this by checking to see if the clipping is
occurring according to the upper left and lower right coordinates of the
map.

Hope this helps,

Don

On Friday, January 11, 2002, at 02:15 PM, Karen Wei wrote:

> Hi,
>
> I just added a Stereographic Projection to Openmap by creating a new
> Stereographic class. It appears to be very similar to Orthographic and
> only required a few code changes for the way the coordinates are
> calculated. It's also plotted on a sphere, similar to Orthographic.
> However, when I zoom in on the Stereographic map, polygons that fall
> only partially on the hemisphere are clipped from the map completely.
> For some reason, it's not taking into account the partial polygons and
> is not adding points that lie on the hemisphere edge in order to
> complete the polygon like Orthorgraphic does.
>
> Does anyone have any ideas as to why there is clipping for Stereographic
> but not Orthographic? And how I can go about fixing this?
>
> Thanks!
> Karen
>
> --
> [To unsubscribe to this list send an email to "majdart@bbn.com"
> with the following text in the BODY of the message "unsubscribe
> openmap-users"]
>
>

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Donald Dietrick, dietrick@bbn.com
BBN Technologies, Cambridge, MA
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

--
[To unsubscribe to this list send an email to "majdart@bbn.com"
with the following text in the BODY of the message "unsubscribe openmap-users"]