Comments on: Implementing a Graphic Driver Abstraction

By: ent

ent — Wed, 23 Apr 2008 10:34:30 +0000

Hi Angelo,

There is one clear advantage to me in using interfaces: hiding the implementation details. Or what is the same: reducing incremental building times. As the architecture grows and grows, building times can easily become a serious bottleneck.

If, when profiling, you discover that the vtable is adding a notable overhead you always can do a simple:

typedef MyInterface MyImplementationClass;

and voila!, your problems disappear.

By: Angelo Pesce

Angelo Pesce — Wed, 23 Apr 2008 02:14:56 +0000

I hate the idea of using pure virtual functions, not because of the overhead but because it’s another, useless class to change when you have to modify a definition. Also it’s not safe, someone could add a function only in the DirectX10 implementation and forget to add it to the abstract interface. Also they are an abuse, an interface that has only one implementation (because the PS3 one won’t be in the X360 project, so in a given project you end up having only one)…
What I did is to have a common header, with platform specific includes for the inline functions and platform specific implementations.

By: pixelame.net

pixelame.net — Thu, 06 Mar 2008 13:01:19 +0000

Implementing a Graphic Driver Abstraction…

En esta entrada del blog de Jesus de Santos, nos explica a rasgos generales los puntos fundamentales a tener en cuenta a la hora de crear la abstraccion del API del rasterizador. Muy recomendado para la gente que esta haciendo motores. No os perdais lo…

By: Ricky

Ricky — Wed, 05 Mar 2008 10:35:10 +0000

Great post!!
I’m looking forward to learn more about this subject in the upcoming course about Videogame Graphics Engines you are going to give for the GameLab on April.

By: Miguel Herrero

Miguel Herrero — Tue, 04 Mar 2008 17:47:55 +0000

Now it makes more sense
Though it seems like it’s hard work.

By: ent

ent — Tue, 04 Mar 2008 16:03:59 +0000

Hi Miguel,

Yes, the GameBryo approach exposes only high level primitives: meshes, particles systems. You implement those primitives in each platform, for example in DX10 you could implement the particles using geometry shaders and export capabilities while you could use dynamic vertex buffers in DX9.

With immediate mode I mean the mode in which the orders send to the API are executed immediately. Of course, you need some kind of batch for the GUI. You should render all the quads with the same texture in a single call.

So, instead of having only a retained mode API, I prefer having a retained mode API implemented using a immediante mode API. This way you can have several retained mode APIs: one for the scene3D, one for the GUI, one for draw debug elements, etc

By: Zalo

Zalo — Tue, 04 Mar 2008 13:23:27 +0000

Pretty interesting

I have applied some of these tips in my engine for DS and Symbian

By: Miguel Herrero

Miguel Herrero — Tue, 04 Mar 2008 08:38:23 +0000

Great post! It was nice to read and still have interesting tips.

I’ve taken the Gamebryo aproach which, if I understood correctly, doesn’t have a custom vertex stream object, but only high level objects isn’t it?

The only thing that surprised me was the ‘immediate mode’ in the GUI. Really? I thought immediate mode was very inneficient and so I only use it to debug.