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Path: utzoo!utgpu!sarathy
From: sarathy@gpu.utcs.utoronto.ca (Rajiv Sarathy)
Date: Tue, 17-Oct-89 17:51:25 EDT
Message-ID: <1989Oct17.175125.23371@gpu.utcs.utoronto.ca>
Organization: University of Toronto Computing Services
Newsgroups: comp.graphics
Subject: Re: Variable-width Bresenham
References: <4162@deimos.cis.ksu.edu>
Reply-To: sarathy@gpu.utcs.UUCP (Rajiv Sarathy)

In article <4162@deimos.cis.ksu.edu> neil@calvin (Neil Erdwien) writes:
>I'm looking for references/ideas for implementing a variable-width
>version of Bresenham's algorithm for quantising line segments.
>
>In other words, I'm not content with single-pixel lines that result
>from the standard algorithm.  I'd like to be able to draw 2, 3, and
>perhaps even fractional line widths.  This seems like a common problem
>and I assume someone has a more elegant solution than just drawing
>multiple closely spaced lines.

How about the next-most obvious way?:

	In the algorithm, plot more pixels:

		If you're stepping by x, then plot as many more pixels as you
		need vertically.

		If you're stepping by y, then plot as many more pixels as you
		need horizontally.


		Example:

			For a 2-pixel-width line with horizontal stepping:

			xx
			**xxxx
			  ****xxx
			      ***

			Where '*' is drawn by Bresenham, and 'x' is drawn
			by your additional SetPixel().

		Of course, you'd need to build in some intelligence to not
		draw over viewport/window/screen boundaries.  You might also 
		want to check to make sure that your lines have even density.

-- 
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