[SDL] 2D API evolution (SDL 1.3/2.0)

Mon Aug 14 17:05:24 PDT 2006

David,

how is the current status of glSDL backend? is there any links to download 
the latest SDL 1.2.11 with it embedded?

also, Im interested on glSDL branches that you have named...again...any 
link?

btw, Im following the SDL 1.3 development to see how we can use opengl or 
d3d to render our 2D stuff.

For the time being...this is an amazing time! soo many news! :)

Cheers!

----- Original Message ----- 
From: "David Olofson" <david at olofson.net>
To: "A list for developers using the SDL library. (includes SDL-announce)" 
<sdl at libsdl.org>
Sent: Monday, August 14, 2006 11:56 PM
Subject: [SDL] 2D API evolution (SDL 1.3/2.0)

>
> I've been thinking about 2D rendering APIs every now and then, and I
> usually come to the conclusion that if you want more than the SDL 1.2
> 2D API, you're better of using OpenGL. (If you're into massive
> blending and transformation effects, and don't care much about non
> hardcore gamers running MS Windows, I still maintain this position.)
>
> However, using OpenGL as the rendering API for a "mostly 2D"
> application has several issues;
>
> * OpenGL is not the safest bet for 3D acceleration
>   on all systems. Some operating systems favor other
>   APIs, and there are 3D accelerators for which there
>   are no OpenGL drivers. Implementing OpenGL over
>   other 3D APIs has proven to be far from trivial, and
>   AFAIK, there are no seriously usable Free/Open
>   Source, or even free-as-in-beer solutions at this
>   point. (Any progress here lately?)
>
> * OpenGL is not available at all on some platforms -
>   even some that provide some, but not all features
>   that are more or less required for accelerated
>   OpenGL. (Consoles and handheld devices, mostly.)
>
> * OpenGL is overkill if you basically just need a
>   supercharger on the rendering backend of the SDL
>   1.2 2D API.
>
> * Software OpenGL implementations are usually
>   (always?) too slow for real time applications -
>   especially on the low end systems that tend to be
>   the ones lacking hardware accelerated OpenGL! The
>   OpenGL API is not designed to support the shortcuts
>   that custom software rasterizers for games need to
>   take to achieve playable frame rates. Meanwhile,
>   most of these shortcuts aren't even relevant to
>   "mostly 2D" applications in the first place.
>
> * Implementing a "mostly 2D" application directly
>   over OpenGL can result in an application that is
>   hard to adapt to software rendering, or less
>   advanced (than OpenGL) accelerated rendering APIs.
>   (Of course, any porting job is complicated when
>   hard to implement features are missing on the
>   target platform...)
>
>
> What I'm thinking is basically something like a subset of OpenGL,
> aimed at 2D rendering with basic transforms and blending. Like the
> current SDL API, it should be easy to understand and use, and
> (relatively speaking) easy to implement in software as well as over
> various 2D and 3D rendering APIs.
>
>
> An alternative to building higher level features into the SDL API to
> allow the backends to accelerate them, is to provide a generic
> "Backend Extension Interface", so that add-on libraries can plug into
> explicitly supported backends to cooperate with them more intimately.
>
> However, I'm worried that such a solution would do more harm than
> good;
> "I'm using SDL_PrimitivesA which works great with
> OpenGL and software - but I need to use the API
> incompatible SDL_PrimitivesB instead to get
> acceleration with Direct3D!"
>
> Maybe it's better to just agree on a feature set, implement software
> fallbacks for it, and then keep any accelerated implementations
> inside SDL. Full acceleration could actually still be provided by
> plugins, to keep the main SDL lib lean and mean, but I have a feeling
> it's not worth the effort.
>
>
> I was inspired to write this part because I've found various extended
> versions of glSDL/wrapper with rotation, scaling, accelerated drawing
> primitives and whatnot. Stuff that isn't too hard to implement in
> software, and that is trivial to implement over OpenGL, Direct3D and
> probably some 2D APIs. Stuff that is pretty much mandatory these
> days, when most 2D games are implemented directly over Direct3D, and
> even casual gamers expect the kind of look and feel that fully
> accelerated 2D can provide.
>
> (The vast majority of these games are developed using various RAD
> tools with integrated support for Direct3D, and in some cases, Linux
> and/or Mac versions that transparently use OpenGL instead. However,
> these tools are not Free/Open Source, and many developers don't care
> much for the language most of these tools use: BASIC. Also, it can't
> be right when the Free/Open Source community is missing something
> that is considered standard in the rest of the world. ;-)
>
> That is, now there are applications that either rely on OpenGL to run
> at all, or have separate backends for "plain" SDL, but still use a
> slightly extended version of the SDL 2D API when rendering through
> OpenGL.
>
> Technically, this could be classified as abuse of glSDL/wrapper, as in
> "They should be writing their own, proper OpenGL wrapper instead!"
> However, I believe it is more useful to take this as a hint as to
> what programmers expect from a 2D API today.
>
> The current situation with the new SDL 1.3 backends, various versions
> of glSDL/wrapper, people writing their own 2D layers over OpenGL
> and/or Direct3D etc is causing confusion, duplication of effort and
> portability issues. Now I'm headed there myself, trying to decide
> whether to rely entirely on OpenGL, implement support for both OpenGL
> and Direct3D and perhaps a software fallback, or maybe investing that
> time in SDL 1.3/2.0 instead, or...?
>
> What are the plans for the 2D API of SDL 1.3 and/or 2.0?
>
>
> //David Olofson - Programmer, Composer, Open Source Advocate
>
> .-------  http://olofson.net - Games, SDL examples  -------.
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