Add C89 support

Allow compilation from C89 compilers.

README

@@ -0,0 +1,189 @@
+TinyGL C89
+==========
+
+TinyGL was originally developed by Fabrice Bellard.
+
+A subtly modified version of TinyGL to support C89 with some of the following
+changes:
+
+- Convert C++ style comments into C89-compliant ones in the following files:
+    - "GLView.h" (line 72)
+    - "light.c" (line 154)
+    - "mech.c" (line 1736)
+    - "zfeatures.h" (lines 38, 40, 41)
+
+- Remove variadic macro in "zgl.h" (line 410).
+
+- Change "static inline" to "static" function in the following files:
+    - "clip.c" (lines 80, 101, 222)
+    - "image_util.c" (line 46)
+    - "light.c" (line 161)
+    - "matrix.c" (line 14)
+    - "vertex.c" (line 148)
+    - "zgl.h" (line 432)
+
+- Define "M_PI" in "gl.h" (Lines 11-13).
+
+- Paste preprocessor output directly into "zgl.h" enumerator and remove old
+  directives (lines 23-89).
+
+NOTE: This modification has not been completely tested and can be improved more,
+as not a lot of time has been put into this fork.
+
+Original README
+===============
+
+TinyGL 0.4 (c) 1997-2002 Fabrice Bellard.
+
+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.)
+
+- MIT license for easy integration in commercial designs (read
+the LICENSE file).
+
+- Subset of GLX for easy testing with X Window.
+
+- GLX like API (NGLX) to use it with NanoX in MicroWindows/NanoX.
+
+- Subset of BGLView under BeOS.
+
+- OpenGL like lightening.
+
+- 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 code size of about 40 kB on x86. The file
+  src/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 sparc-Solaris.
+
+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/GLX implementation. You can also compile them with
+Microwindows.
+
+- texobj illustrates the use of texture objects. Its shows the speed
+of TinyGL in this case.
+
+- glutmech comes from the GLUT packages. It is much bigger and slower
+because it uses the lightening. I have just included some GLU
+functions and suppressed the GLUT related code to make it work. It
+shows the display list handling of TinyGL in particular. You can look
+at the source code to learn the keys to move the robot. The key 't'
+toggles between shaded rendering and wire frame.
+
+- 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).
+
+- GLX interface (zglx).
+
+To use TinyGL in an embedded system, you should look at the GLX layer
+and modify it to suit your need. Adding a more user friendly
+developper layer (as in Mesa) may be useful.
+
+Notes - limitations:
+--------------------
+
+- See the file 'LIMITATIONS' to see the current functions supported by the API.
+
+- The multithreading could be easily implemented since no global state
+is maintainted. The library gets the current context with a function
+which can be modified.
+
+- The lightening is not very fast. I supposed 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.
+
+- List sharing is partialy supported in the source, but not by the
+current TinyGLX implementation (is it really useful ?).
+
+- 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.
+
+- The resizing of the viewport in TinyGLX ensures that the width and
+the height are multiples of 4. This is not optimal because some pixels
+of the window may not be refreshed.
+
+Why ?
+-----
+
+TinyGL was developped 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.
+
+--- end of Original README ---
+
+--- end of README ---