Original Post
First off, Project Platform: DOS / DJGPP / Allegro
Alright, a while ago I programmed a library that included a less-than-half-implemented set of dirty rectangle routines (in C) for a simple engine class. I've used this engine with Allegro projects for about a year now, and I've decided to actually try to fully implement an accurately-working dirty rectangle drawing routine, as most of my projects are either Fallout-like (screen stays still until the user scrolls), or contain bitmapped menu screens, or somewhere have situations where dirty rectangles would be optimal.
Currently, this is the process I use:
1 store background image in bitmap "backpage"
2 reset dirty rectangle list
3 draw all sprites (words, mouse cursor) on "page"
4 blit all of "page" to "screen"
5 blit "backpage" to "page" using dirty rectangle list
6 goto 2
So basically the only performance gain I'm achieving using this hack job is that I don't have to clear the entire page next cycle. 
If I do this:
1 store background image in bitmap "backpage"
2 reset dirty rectangle list
3 draw all sprites (words, mouse cursor) on "page"
4 blit all of "page" to "screen" using dirty rectangles
5 blit "backpage" to "page" using dirty rectangle list
6 goto 2
..then all the elements that got blitted to "screen" leave mouse-dropping-like artifacts behind, which is a Very Bad Thing.
If anyone could tell me how to actually do the correct dirty rectangles process (with optimizing/sorting of the dirty rectangles, etc.), then I would be as happy as a cheerleader on drugs.
And, on the side, ICQ me if you want to chat about design theories, RPG battle systems, or if want me to send a demonstration of the problem.
____
Kevin Dickerson
Edited by - Sparcbot on 3/28/00 6:55:49 PM
If I do this:
1 store background image in bitmap "backpage"
2 reset dirty rectangle list
3 draw all sprites (words, mouse cursor) on "page"
4 blit all of "page" to "screen" using dirty rectangles
5 blit "backpage" to "page" using dirty rectangle list
6 goto 2
..then all the elements that got blitted to "screen" leave mouse-dropping-like artifacts behind, which is a Very Bad Thing.
If anyone could tell me how to actually do the correct dirty rectangles process (with optimizing/sorting of the dirty rectangles, etc.), then I would be as happy as a cheerleader on drugs.
And, on the side, ICQ me if you want to chat about design theories, RPG battle systems, or if want me to send a demonstration of the problem.
____
Kevin Dickerson
Edited by - Sparcbot on 3/28/00 6:55:49 PM