Misc GapiDraw Questions

by **mlepage** » Sep 11, 2003 @ 4:19am

How do I create a new surface that is a copy of an existing surface? (Say, to take a copy of the back buffer.) Can I just use the copy constructor?

by **InexorableTash** » Sep 11, 2003 @ 4:22am

Create a new surface the same width and height, and then BltFast.

(I would highly recommend against copy constructors being used for this sort of thing. C++ compilers like to use them in all sorts of places you wouldn't expect, and with a large memory copy you could find performance hits you weren't expecting.)

by **mlepage** » Sep 28, 2003 @ 6:05am

by **Johan** » Sep 28, 2003 @ 11:27am

by **mlepage** » Oct 18, 2003 @ 5:41am

by **mlepage** » Feb 9, 2004 @ 5:10am

by **mlepage** » Feb 9, 2004 @ 6:18am

by **InexorableTash** » Feb 12, 2004 @ 5:31am

You don't have to use the CGapiApplication frame timer mechanism; I'd recommend either rolling your own, or instead of using frame ticks switching to absolute times (e.g. your high performance tick counts) to position items in the game world.

Think about this scenario: average frames take 20ms, per-frame time is set at 30ms (so 33.3 frames per second - that makes the other number round). So on average, the timer is going to sleep for 10ms per frame. Now you run into a frame that takes 45ms to render. Now, the timer would have to sleep for -5 seconds to catch up.

Most commercial games that I've seen either just "stutter" when there's an intense frame (e.g. the game slows down when there's lots of activity) or use absolute times (e.g. it takes 5 seconds for a ship to fly across the screen, whether that's 1 frame or 150 frames). In the latter case you probably want to cap the frame rate at some reasonable number so you're not consuming 100% CPU. The CGapiApplication timer seems to be an adequate implementation for both scenarios, but may not be for yours.

by **mlepage** » Feb 12, 2004 @ 6:26am