## Re: [Algorithms] Draw & fill regular polygon?

 Re: [Algorithms] Draw & fill regular polygon? From: Martin Gladnishki - 2011-08-11 06:05:35 Attachments: Message as HTML ```There are also a number of line rasterizing algorithms that do 2, even 3 pixels per iteration, i.e. with them you will be able to fill the arrays faster. Lookup for double-step rasterizing algorithms. Also, in my experience the extrema arrays are not needed: for convex polygons there are only two active edges at a time, therefore you just need to traverse the poly in clockwise and anti-clockwise order to switch the active edges until they meet at the maximum Y coordinate. Hope that helps further. Cheers, Martin On Wed, Aug 10, 2011 at 6:29 PM, Graham Rhodes ARA/SED wrote: > Some helpful Google search terms are "polygon rasterization" and "polygon > scan conversion." Someone else mentioned the Foley/van Dam book/et al. book, > which is a good reference that describes the classic algorithm. The book > Graphics Gems I also has a discussion, though it is brief. You can also find > this stuff online, for free. For example, two sets of lecture slides from > University of Virginia that look good: > > > http://www.cs.virginia.edu/~gfx/courses/2004/Intro.Fall.04/handouts/11-polyscan.pdf > http://www.cs.virginia.edu/~asb/teaching/cs445-fall06/slides/09-rasterization.ppt; > > I even found this YouTube video: > > http://www.youtube.com/watch?v=TNbkX5bYrtE > > Graham > > -----Original Message----- > From: Joel B [mailto:onephatcat@...] > Sent: Wednesday, August 10, 2011 7:49 AM > To: Game Development Algorithms > Subject: [Algorithms] Draw & fill regular polygon? > > I should know how to do this, but i don't. I only have the ability in my > system to draw lines (x1,y1,x2,y2)' to a bitmap, or write to the bitmap as a > byte array. Can someone tell me the stepwise procedure to draw a polygon of > n sides and then fill it? Having trouble finding anything online that > doesn't use pre-existing primitives or libraries. > > Thanks, > > Joel > Sent from my iPhone > > ------------------------------------------------------------------------------ > uberSVN's rich system and user administration capabilities and model > configuration take the hassle out of deploying and managing Subversion and > the tools developers use with it. Learn more about uberSVN and get a free > download at: http://p.sf.net/sfu/wandisco-dev2dev > _______________________________________________ > GDAlgorithms-list mailing list > GDAlgorithms-list@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithms-list > > > ------------------------------------------------------------------------------ > uberSVN's rich system and user administration capabilities and model > configuration take the hassle out of deploying and managing Subversion and > the tools developers use with it. Learn more about uberSVN and get a free > download at: http://p.sf.net/sfu/wandisco-dev2dev > _______________________________________________ > GDAlgorithms-list mailing list > GDAlgorithms-list@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithms-list > ```