Gfx Performance

[Adventus]

Im considering moving into the GP2X game development scene, but first i would like to know what this interesting little machine is capable of, particularly in the graphics department. I have some experience (2 years) in the indie game scene and I'm moderately fluent in OpenGL and C++.... Still I'm not quite willing to write my own software rasterizer....

I've seen the gpu940 egoboo port (quite impressive) amongst other things (Quake, PSX emu, etc), and i have a few questions i hope you guys can answer:

• 1. In the current gpu940 build what is a feasible maximum onscreen textured triangle count at say 266mhz and 25~30fps (non-perspective & no z buffer) ?.
• 2. Would gpu940 be a good choice for a 2d topdown game which relies heavily on screen and sprite rotation? or would Vincent/Hw SDL be faster?.... Payback proves this type of game is possible (with Additve Bloom and lightmaps to boot), although im not aiming for that level of 3d-ness.
• 3. Does gpu940 perform hidden surface removal? Im guessing it does....
• 4. Does gpu940 support any varieties of blending? i.e. additive, alpha, etc.

Sorry if these questions have been asked before, but i cant seem to find anything specifically relating to what im asking. Also note that i do not currently have a GP2X in my sweaty paws (ill wait for the F200), so dont tell me to test it myself. XD.

 

[letsridebmx104]

F-200 is coming out this month ... preorder yours now

 

[Adventus]

QUOTE
F-200 is coming out this month ... preorder yours now
Well aware, twas just hoping I could guage its performance before i decided on whether a PSP would better suit me.

 

[Squidge]

If your into 3D software development, then the 2X will be a poor choice. You would be better with the PSP which has hardware 3D support (or perhaps wait till next year for the Craiginator which will be more than twice as fast as the 2X and have hardware 3D, yet still be homebrew friendly)

 

[Adventus]

QUOTE
If your into 3D software development, then the 2X will be a poor choice. You would be better with the PSP which has hardware 3D support (or perhaps wait till next year for the Craiginator which will be more than twice as fast as the 2X and have hardware 3D, yet still be homebrew friendly)
Im not hugely interested in raw perspective 3d.... fairly intensive 2d is more my focus (payback is probably prettier/more intensive than what i aim for). I would mainly be using a 3d engine so that rotations are faster/less ram intensive.

Yea the PSP sounds good, but im somewhat adverse to the Sony attitude.... im also unsure about how much homebrew support is available.... and it'll probably cost about $150+AU more.

The craiganator sounds almost too good to be true, but im not willing to wait that long.... Im sure if its as good as it sounds it'll find its way into my hands some way or another.

 

[skeezix]

For rotations and scaling .. you woudl likely just use some functions, or write your own, rather than a '3d engine' (that term implies a whole lot more .. surfacve removal and so forth, shading etc).

PSP homebrew is wide open at any given time, but down the road they might shut it down; if you never upgrade.. if you just get a PSP for homebrew, then you're always good for it. Its only a problem if you're chasing the latest firmwares and/.or games, before they've been cracked open. (Or if all the firmware hackers bail out.) So far, every firmware is wide open.

GP2x is easiest handheld to code for, but its all roll-your-own; if you want 3d, you'll not be using some handy lib since it wouldn't be optimized enough to be useful probably; that said, 200MHz or so can do okay as you've seen with payback..

jeff

 

[jimmyslam]

Basically gp2x is good for 2D. We have emulated games running @60FPS like NEOGEO,CPS2, Megadrive, games... and that is emulation... I dont think we have seen any great good homebrew game yet... I was making one, without any acceleration and the tests point that was good so far.

http://www.youtube.com/watch?v=OP6z49fEBx4

I wont carry on with it until i finish a project I ma working on right now.

 

[Adventus]

QUOTE
For rotations and scaling .. you woudl likely just use some functions, or write your own, rather than a '3d engine' (that term implies a whole lot more .. surfacve removal and so forth, shading etc).
I was assuming something like gpu940 would, despite some inherent overhead, be able to render a rotated quad faster using scanline algorithms.... rather than using SDL rotozoom/"whatever i come up" with functions. Compare DirectDraw with Direct3d and you'll understand where im coming from. I wonder if i could write a fast enough bilinear rotozoom (without learning ASM)....

QUOTE
Basically gp2x is good for 2D. We have emulated games running @60FPS like NEOGEO,CPS2, Megadrive, games... and that is emulation... I dont think we have seen any great good homebrew game yet... I was making one, without any acceleration and the tests point that was good so far.
Looks pretty nifty. You've got quite a decent amount of onscreen sprites there, especially for a software render.

Anyway, i've pretty much given the boot to the PSP.... for now, i'll pre-order a F200.

 

[woogal]

I'm not sure why you think that a 3d engine running on 2d hardware would be faster than a 2d engine running on 2d hardware.

 

[Adventus]

QUOTE
I'm not sure why you think that a 3d engine running on 2d hardware would be faster than a 2d engine running on 2d hardware.
Yea it probably wasn't a good analogy. Its just the technique thats being used (scanline vs blitting) and what ever other optimisations (ie better ASM production, frustum culling, etc) are possible. Im not saying a purpose built 2d algorithm wouldn't be faster, just that gpu940 might be faster than what i could be bothered to write.... at least initially.

You do have a point thou, obviously im used to PC dev.... im relativelty ignorant of software rendering. Eventually i will end up writing my own 2d library for the 940.