ref: e2e12c60ee18888709eaccaa8fc55b7c9fb3cf45
dir: /README.md/
# TinyGL- New and Improved A rework of Fabrice Bellard's TinyGL (still compiling with -std=c99) to be more useful as a software rasterizer. Without Polygon Stipple:  With Polygon Stipple:  Hello World test:  Texturing Test:  Model loading tests:   TinyGL 0.8 (c) 1997-2021 Fabrice Bellard, C-Chads, Gek (see License, it's free software) This is a maintained fork of TinyGL, by the C-Chads. It is a small, suckless Software-only partial GL 1.1 implementation. The original project was by Fabrice Bellard. We have forked it. The changelog is as such: * Disabled 8, 15, and 24 bit rendering modes. 16 and 32 are the only supported rendering modes (Coincidentally, they are also the fastest) * Implemented new functions and some of GL 1.1's prototypes including polygon stipple. * Fixed a myriad of bugs and... weirdnesses Note that this Softrast **is not GL 1.1 compliant** and does not constitute a complete GL implementation. You *will* have to tweak your code to work with this library. That said, once you have, it will run anywhere that you can get C99. TinyGL has very few external dependencies. Notable limitations: * The only supported texture size and format is RGB 256x256 * there is no GL_BLEND compatibility whatsoever * A lot of prototypes are missing. * A triangle cannot be textured and lit at the same time. (This is planned to be fixed) * <Undocumented limitations that have not been tested> ### NEW FUNCTIONS These are functions not in the GL 1.1 spec that i've added to make this library more useful. These functions cannot be added as opcodes to display lists. ### glDeleteList An easier to use version of glDeleteLists. glDeleteLists is also implemented. ### glSetEnableSpecular(int shouldenablespecular); Allows you to configure specular rendering. Turn it off if you want to use GL_LIGHTING but don't plan on using specular lighting. it will save cycles. ### glGetTexturePixmap(int text, int level, int* xsize, int* ysize) Allows the user to retrieve the raw pixel data of a texture, for their own modification. ### glDrawText(const unsigned char* text, int x, int y, unsigned int pixel) This function can be added to display lists. Draws a pre-made 8x8 font to the screen. You can change its displayed size with... ### glTextSize(GLTEXTSIZE mode) This function can be added to display lists. Set size of text drawn to the buffer in aforementioned function. ### glPlotPixel(int x, int y, unsigned int pixel) This function can be added to display lists. Plot pixel directly to the buffer. ## TOGGLEABLE FEATURES See `include/zfeatures.h` Standard OpenGL features that you can disable for extra performance or smaller binary size. Note that Polygon Stipple is OFF by default, to improve performance. ```c #define TGL_FEATURE_ARRAYS 1 #define TGL_FEATURE_DISPLAYLISTS 1 #define TGL_FEATURE_POLYGON_OFFSET 1 #define TGL_FEATURE_POLYGON_STIPPLE 0 ``` Change the dimensions of a polygon stipple pattern, and how it's interpreted. If you're only ever going to use very small stipple patterns, it's recommended you alter these settings. ```c //A stipple pattern is 128 bytes in size. #define TGL_POLYGON_STIPPLE_BYTES 128 //A stipple pattern is 2^5 (32) bits wide. #define TGL_POLYGON_STIPPLE_POW2_WIDTH 5 //The stipple pattern mask (the last bits of the screen coordinates used for indexing) //The default pattern is 32 bits wide and 32 bits tall, or 4 bytes per row and 32 tall, 4 * 32 = 128 bytes. #define TGL_POLYGON_STIPPLE_MASK_X 31 #define TGL_POLYGON_STIPPLE_MASK_Y 31 ``` These features enable you to achieve the effect of `discard` in GLSL shaders. You can use this to draw objects which only ever need discard-type alpha transparency. Simply specify a color to use for that purpose. My favorite choice is hideous magenta (0xff00ff) The color mask is "and'd" with the color before the test, in case you wanted to only test one color (red, for instance) Note that when changing between bit depths, you will need to alter the NO_COPY_COLOR and NO_DRAW_COLOR if you use those features. ```c #define TGL_FEATURE_NO_COPY_COLOR 0 #define TGL_FEATURE_NO_DRAW_COLOR 0 #define TGL_FEATURE_FORCE_CLEAR_NO_COPY_COLOR 0 #define TGL_NO_COPY_COLOR 0xff00ff #define TGL_NO_DRAW_COLOR 0xff00ff //^ solid debug pink. #define TGL_COLOR_MASK 0x00ffffff ``` Alter the bit depth of rendering. Note that all textures loaded are assumed to be R8G8B8 (in that order, with no Alpha or padding) Textures are converted internally (see image_util.c) to the renderer's output format. at the current time, only 16 and 32 bit rendering are maintained and tested regularly. ```c #define TGL_FEATURE_8_BITS 0 #define TGL_FEATURE_24_BITS 0 //These are the only maintained modes. #define TGL_FEATURE_16_BITS 0 #define TGL_FEATURE_32_BITS 1 ``` ## FIXED BUGS FROM THE ORIGINAL! TinyGL 0.4 by Bellard had incorrect color interpolation and issues with GL_FLAT, causing the hello world triangle to look rather... wrong. Additionally, per vertex color is just cool. ## Notorious bugs from the original that have been fixed * GLParam is a union of float, int, uint, and void* which is assumed to be 32 bit... but isn't on 64 bit systems * Per vertex color is broken due to a faulty optimization in clip.c * The conventions for 32 bit color were RGBA for textured triangles and ABGR for non-textured. Now both render as ABGR. * Little endian was assumed in a thousand places in the code * Non-normalized position was used for lights at infinity. * Insert unknown bugs here. ## FULLY COMPATIBLE WITH RGBA! The library is now able to be configured properly for RGBA rendering. Note that the output *is actually ABGR* but adjusting it is easy, see the SDL examples under SDL_EXAMPLES (They require SDL 1.2 and Mixer to compile) The library is sometimes by default configured for RGBA or 5R6G5B, check include/zfeatures.h and change the values in this table: ```c #define TGL_FEATURE_8_BITS 0 #define TGL_FEATURE_24_BITS 0 //These are the only maintained modes. #define TGL_FEATURE_16_BITS 1 #define TGL_FEATURE_32_BITS 0 ``` make sure that only ONE of these values is 1. ## ALSO COMPATIBLE WITH 16 BIT # Here is the old description of TinyGL, saved for historical/attribution purposes: ### 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). - 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.