GX matrices

[davidgf]

Hello!

I'm writing an OpenGL like implementation for GX (more a wrapper than an implementation) and I'm facing problems with some matrices.
Why the matrices involved at gluPerspective differ from the GU one? The calc. is slighlhy different.

Thank you very much!

David

[Izhido]

I'm not an expert, or anything. However, from the DS side, I've noticed that the hardware 3D support is considerably different from what one would expect from OpenGL. A hint from this can be found in the fact that, again under DS, you can actually change *all of your matrices* while inside a glBegin() / glEnd() block, something that the standard strictly forbids. It's like OpenGL support was never considered for the hardware. Maybe that's what happens with Wii's hardware?

Having an OpenGL wrapper for Wii/DS is a good idea... for a few first attempts to coding with the consoles. As you grow, you'll find the hardware is different AND capable of much more, and you will want to go as close to the hardware as possible. In my opinion, and as someone who already tried creating an OpenGL wrapper to the DS, it's not that good of an idea to create such a wrapper, when it will end up not being used for serious coding.

My 2c.

[davidgf]

Hi!

I understand your example but that's not representative. I mean, the base of a 3D system is matrix-vector transformation. Based on this the matrices should be all equal and therefore obtain the same results. So there must be different matrix operations than just plain matrix multiplies right?

I can't find any documentation with high detail on the topic. Someone?

And about the "it will end up not being used for serious coding" you have to consider that there aren't great 3D HB games for Wii, so a OGL wrapper will help a lot porting games. Although dealing with low level stuff is cool while learning it isn't when you develop real software because you'll waste lot of time on system dependent code. I prefer lower performance and features and having a standard API, and the market too!

[WinterMute]

The 3D hardware in the Gamecube and the Wii wasn't designed with openGL in mind, several people have attempted a gl wrapper of sorts and not really got anywhere.

I know shagkur was working on an Irrlicht port he called wiirlicht but I'm not sure how far he got with that. There's also a cross platform 3D library called libknowledge which had wii and gamecube support. Either of these would be much better for your purposes than attempting to port openGL.

[davidgf]

Yeah, I got it. The fact is that the matrices ara slightly different but I made them work.
BTW I've managed to implement the basic things: texture loading (f*ck texture scrambling!), immediate mode, glDraw glPointer functions, matrix, blending, etc...

At this moment I've managed to integrate it on SDLWii and SDLGc and my project work perfect without changing any code! I prefer SDL+OGL because it's portable, I can run my game on PC/PSP/Wii/GC which is great!

I'll show:

http://img593.imageshack.us/i/screengnc.png/