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Graphics > GBA 3D Performance (Mode 5 rotated)

#7737 - Cranium Megahurt - Mon Jun 23, 2003 7:10 pm

Just a few quick questions about performance of the GBA in a particular situation... I know many here will not know the exact answer, but I would appreciate estimations and guestimations...

1. When you use Mode 5 (160x128x16bit) and rotate it, I've read in a faq that you need to kill 8 pixels for a smooth image. I can understand why you would want to do this for smooth diagonal lines from one corner of the screen to another, but is it really necessary? And more importantly, does it increase performance by a corresponding amount?

2. What sort of performance are the middle-of-the road 3D engines getting? In polygons and pixels per sec... And what sort of performance are the high-end engines getting?

3. Any word on purchasing/licensing a 3D engine? Reasonable or absurd?

Sorry to sound like such a moron about this.
_________________
"I see dead pixels..."

#9584 - Derek - Sat Aug 09, 2003 2:20 pm

The GBA has 240x160 pixels. Resizing from 128 to 240 means each pixel is 240/128 = 1.875 in width.

Therefore, some pixels will double and some will remain single pixels. This causes visible aliasing in 2D. In 3D, the aliasing isn't that noticable since DDA rendering adds its own fair share of visible artifacts.

If you accept a resolution of 160x120 and rotate/expand, then you get a perfect 120x160 resolution and each pixel is doubled in size. ie: 240/120 = 2

I've heard most pro-engines are aiming for 15-20 FPS. When DOS Quake came out, I remember 15FPS was often the minium speed.

RE: Licensing. It seems like Torus Games hold the standard for FPS engines on the GBA.

I developed this engine which has just been released. Email me for the source code, or wait a couple of weeks for me to organise myself.

http://www.theteahouse.com.au/gba/index.html

Derek Evans