Michael Abrash’s Mode-X articles in DDJ and Chris Hecker’s Game Developer articles on perspective correct texture mapping should be required reading for anybody interested in this kind of thing.

My Google-fu failed to turn up Abrash’s articles but it sounds like they were reprinted in his Graphics Programming Black Book special edition.

Chris Hecker’s series of articles on perspective texture mapping can be found on his website: http://chrishecker.com/Miscellaneous_Technical_Articles#Perspective_Texture_Mapping

Cheers

Derek

Sent: Thursday, 11 August 2011 4:05 PM
To: Game Development Algorithms
Subject: Re: [Algorithms] Draw & fill regular polygon?

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 <grhodes@ara.com> 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
www.cs.virginia.edu/~asb/teaching/cs445-fall06/slides/09-rasterization.ppt

I even found this YouTube video:

Graham

-----Original Message-----

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
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