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2D polygon interior detection

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06 Jun 2010 (Updated )

Detect a whereas a point is interior or exterior to a 2D polygon

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Description

This function tries to improve the slow Matlab INPOLYGON function.

There are few other fast codes on FEX (e.g., by Darren Engwirda). After exploring many different ways, I come to the conclusion that Darren Engwirda's approach is close to optimal. So here you'll find a general method that share many common aspects, but implemented in C-Mex. I have makes few contributions: (1) a lean C-implementation, (2) Using Matlab SORT and HISTC for binning, (3) Derive an empirical rule when to apply the sorting, (4) a more rigorous on-boundary detection.

Acknowledgements

This file inspired Flow Cytometry Gui For Matlab.

MATLAB release MATLAB 7.10 (R2010a)
Other requirements Mex setup
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Comments and Ratings (5)
29 Oct 2014 Roger GALLOU  
04 Feb 2014 Jeffrey Steward  
22 Oct 2012 David  
07 Jun 2010 Bruno Luong

To Matt: this is algorithm designed for for generic polygons (as with INPOLYGON)

07 Jun 2010 Matt J

Does this submission apply to convex polygons or general ones? If the latter, there should be a way to make it faster if the polygon is known a priori to be convex. Perhaps an input parameter to enable this...

Updates
07 Jun 2010

Change the criteria to trigger the presorting step

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