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From: schwager@m.cs.uiuc.edu
Newsgroups: comp.sys.amiga.tech
Subject: Clicking on Irregular Shapes
Message-ID: <42700015@m.cs.uiuc.edu>
Date: 20 Jun 89 23:16:02 GMT
Lines: 29
Nf-ID: #N:m.cs.uiuc.edu:42700015:000:1488
Nf-From: m.cs.uiuc.edu!schwager    Jun 19 17:35:00 1989


Hope someone can help with this C question:

Given an irregularly shaped object on a Screen, how can one tell if
the mouse button has been pressed inside of it?  I don't want a box all
around or inside it; I want the object and exactly the object.  Here's
why I ask: I'm going to be drawing a map on the screen (into a Backdrop
window of a workbenchscreen) and I want to be able to select individual
countries.  Take something like Italy- if the user selects the toe of
the boot or the top, it should acknowledge either.  But I don't want them
to be able to select Italy while they're just a tad into Switzerland.  Nor
do I want them to be able to click in a corner of Italy and have them
wondering why the Amiga didn't grab their click.

I was looking at info about gadgets, but I didn't find them handy cuz
the active part is a box.  I don't like the way collision detection is
handled with Bobs, either (I was thinking of checking the collision of
the mouse pointer with Bobs- but the way it's done, the collision
borders for the Bob become a square, also).

Also- the countries will be bordered, if that helps.  Maybe I need to
define my countries by a series of borders, and see if the mouse click
falls inside a border.

So, wizened ones, can anyone help or point me in the direction of some
sample code?  Thanks.
-Mike Schwager				schwager@a.cs.uiuc.edu
-- {uunet,convex,pur-ee}!uiucdcs!schwager   schwager%uiuc@csnet-relay.arpa
	University of Illinois, Dept. of Computer Science