TinyGL 0.4 (c) 1997-2002 Fabrice Bellard. TinySDGL 0.5, 2005 a port to libSDL by Gerald Franz (gfz@o2online.de). General Description: -------------------- TinyGL is intended to be a very small implementation of a subset of OpenGL* for embedded systems or games. It is a software only implementation. Only the main OpenGL calls are implemented. All the calls I considered not important are simply *not implemented*. The main strength of TinyGL is that it is fast and simple because it has not to be exactly compatible with OpenGL. In particular, the texture mapping and the geometrical transformations are very fast. The main features of TinyGL are: - Header compatible with OpenGL (the headers are adapted from the very good Mesa by Brian Paul et al.) - Zlib-like licence for easy integration in commercial designs (read the LICENCE file). - Examples that show the integration into the platform-independent libSDL (http://www.libsdl,org) - Easy porting to further platforms, since all platform-specific code has been moved from the core library into the examples. - OpenGL like lighting. - Complete OpenGL selection mode handling for object picking. - 16 bit Z buffer. 16/24/32 bit RGB rendering. High speed dithering to paletted 8 bits if needed. High speed conversion to 24 bit packed pixel or 32 bit RGBA if needed. - Fast Gouraud shadding optimized for 16 bit RGB. - Fast texture mapping capabilities, with perspective correction and texture objects. - 32 bit float only arithmetic. - Very small: compiled (and stripped) code size of about 40 kB on x86. The file include/zfeatures.h can be used to remove some unused features from TinyGL. - C sources for GCC on 32/64 bit architectures. It has been tested succesfully on x86-Linux and MS Windows. Examples: --------- I took three simple examples from the Mesa package to test the main functions of TinyGL. You can link them to either TinyGL, Mesa or any other OpenGL implementation. - texobj illustrates the use of texture objects. Its shows the speed of TinyGL in this case (example not included in TinySDGL). - You can download and compile the VReng project to see that TinyGL has been successfully used in a big project (http://www-inf.enst.fr/vreng). Architecture: ------------- TinyGL is made up four main modules: - Mathematical routines (zmath). - OpenGL-like emulation (zgl). - Z buffer and rasterisation (zbuffer). To use TinySDGL in a further system, you should look at the examples and replace the SDL specific code by corresponding commands. Notes - limitations: -------------------- - 24 BIT packed pixel format seems not to work correctly under libSDL. - See the file 'LIMITATIONS' to see the current functions supported by the API. - Multithreading could be easily implemented since no global state is maintained. The library gets the current context with a function which can be modified. - Lightening is not very fast. I suppose that in most games the lightening is computed by the 3D engine. - Some changes are needed for 64 bit pointers for the handling of arrays of float with the GLParam union. - No user clipping planes are supported. - No color index mode (no longer useful !) - The mipmapping is not implemented. - The perspecture correction in the mapping code does not use W but 1/Z. In any 'normal scene' it should work. Why ? ----- TinyGL was developed as a student project for a Virtual Reality network system called VReng (see the VReng home page at http://www-inf.enst.fr/vreng). At that time (January 1997), my initial project was to write my own 3D rasterizer based on some old sources I wrote. But I realized that it would be better to use OpenGL to work on any platform. My problem was that I wanted to use texture mapping which was (and is still) quite slower on many software OpenGL implementation. I could have modified Mesa to suit my needs, but I really wanted to use my old sources for that project. I finally decided to use the same syntax as OpenGL but with my own libraries, thinking that later it could ease the porting of VReng to OpenGL. Now VReng is at last compatible with OpenGL, and I managed to patch TinyGL so that VReng can still work with it without any modifications. Since TinyGL may be useful for some people, especially in the world of embedded designs, I decided to release it 'as is', otherwise, it would have been lost on my hard disk ! ------------------------------------------------------------------------------ * OpenGL(R) is a registered trademark of Silicon Graphics, Inc. ------------------------------------------------------------------------------ Fabrice Bellard. (Minor changes by Gerald Franz)