Last updated: 1.11.2005
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General
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   This folder contains the files needed to implement the Polygon Clipper "gpc" in Matlab.

   Credit for the gpc-library goes to ... 

	Alan Murta
	Advanced Interfaces Group
	Department of Computer Science
	University of Manchester
	Manchester M13 9PL, UK
	http://www.cs.man.ac.uk/~toby/alan/software//
	
	The gateway to Matlab has been designed to work for the library version gpc 2.32 (included in this folder).
	If compiled with past resp. future versions of gpc, the gateway might also work, however I can not assure this and
	I will not give any support for versions other than 2.32 ...
	

Description
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	The Polygon Clipper is used to calculate ...
		... difference
		... union
		... XOR
		... AND
	between two arbitrary polygons. Each polygon may be constructed of several contours and may contain holes (s.examples).
	
Content
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	Files in this folder are ...
	gpc.*:               Original Polygon Clipper files taken from the above home page (used Version: 2.32)
	gpc_mexfile.*:       File containing the mexfile, i.e. the gateway between Matlab and the gpc library.
	PolygonClip.dll:     Comiled library (mex-file for windows), which can be called from Matlab (s. Example.m).
	                     If this file does not work for you (e.g. under Linux), you will have to recompile.
	Example.m:           Simple example file, which demonstrates how to use the library in Matlab.
	ReadMe.txt:          This file

Examples
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	Try out the file Example.m for a demonstration in Matlab.
	Alan Murta's home page offers general examples (e.g. for Windows: ftp://ftp.cs.man.ac.uk/pub/toby/gpc/gpc_test.zip).


How to compile
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	If you need to recompile the code, e.g. for Linux, try the following command, which worked for me:
	
		mex gpc.c gpc_mexfile.c -O -output PolygonClip              % optimized
		mex gpc.c gpc_mexfile.c -argcheck -output PolygonClip       % with argument checking
		mex gpc.c gpc_mexfile.c -g -output PolygonClip              % for debugging
		
	You need a C-compiler installed on your computer for this to work.
	
Bugs
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    ??? 1) It seems that the routine is sometimes passing back empty arrays (0 vertex). This should be handled. ???

PS ...
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	I'm not exactly an experienced C-programmer. If you have any suggestions for improving the gateway, i.e. the files 
	gpc_mexfile.* (and only these files!!!), I will incorporate necessary changes.
	
Author (for gateway)
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	Dipl. Geophys. Sebastian Hölz
	Geophysik
	TU Berlin
	Germany
	hoelz_*_geophysik.tu-berlin.de   
	(replace _*_ with @)
	