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C-Chads / tinygl

The penultimate portable graphics library
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c c99 cpp embedded fabrice-bellard opengl portable rasterizer tinygl

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TinyGL

tgl logo A major overhaul of Fabrice Bellard's TinyGL to be more useful as a software rasterizer.

Now with limited multithreading support

Tightly tweaked and tuned for performance

The library has been tightly tuned using valgrind, perf stat, and other tools.

On a single thread on an i7-6700 (Skylake, 2015), the standard "gears" demo runs at a higher framerate than glxgears on Mesa using a Ryzen 3900x (2019) (NOTE: TinyGL Compared without SDL overhead)

I think I can safely say, this is the fastest single-threaded FOSS software GL implementation in existence.

It's probably also the most portable

Safety features

TinyGL contains the following safety features:

  1. compiletime options for glGetError() functionality which obviously slows down speed but increases debugging capability.

  2. OpenGL 2.0 buffers, for easy memory management (Anything you put in a buffer using glBufferData will be free'd upon glClose())

  3. Fully leak checked using Valgrind- The only leaks you'll see are from your system's SDL. the Raw demos have zero leaks.

Incredibly portable

TinyGL is written in pure C99, and requires very few functions from the C standard library, it doesn't even require malloc and free (The calls are aliased to gl_malloc() and gl_free(), which you can replace with your own memory management model if you desire)

How portable?

The SDL examples are now confirmed building with TCC, using TinyCC built from the latest source.

You can test compiling TinyGL and running it on platforms without SDL by running the RAW DEMOS, which do not require ANYTHING Except the C standard library and stdio. You may have to change the destination written to by the raw demos on platforms without standard file systems.

These are the C standard library includes used in the RAW DEMOS.

#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>

If your system supports it, the library can also take advantage of alignas to get improved SIMD support, which can be disabled in zfeatures. This adds a dependency to stdalign.h but greatly increases vertex processing speed.

(This is disabled by default for maximum portability)

If you are unsure if your target platform can support TinyGL, compile it with the buildtime and runtime tests enabled (They are, by default)

if you get a TGL_BUILDT error, then you've failed the buildtime test.

if you try to initialize the library and you get a crash with a print to standard out "TINYGL_FAILED_RUNTIME_COMPAT_TEST" then you've failed the runtime test.

The SDL examples have been tested building on Debian 10 and Windows 10, while tinygl itself has been confirmed to compile on many more platforms.

Includes a small SIMD-accelerated public domain replacement for GLU

the "Chad Math Library" has been included (CC0, public domain) for your programming needs.

it is simd accelerated on supported platforms, but it contains ZERO platform-specific code- it relies on an optimizing compiler to get vectorized ops. SIMD acceleration is improved by enabling alignas.

NOTE: There are graphical artifacts visible in these gifs which have been corrected in this version of the library.

Without Polygon Stipple:

GIF Video of demo

With Polygon Stipple:

GIF Video of demo

Hello World test:

model loading demo

Texturing Test:

Screenshot of Texture test

Model loading tests:

model loading demo

model loading demo

Without lighting:

model loading demo

model loading demo

This is a demo of the NO_DRAW_COLOR feature. Notice that the object appears to have a hole in it.

model loading demo

Blending:

model loading demo

Specular:

GIF Video of demo

OpenIMGUI standard demo:

OpenIMGUI

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:

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:

HOW DO I USE THIS LIBRARY???

TinyGL is not header only, it is a combination of C files, internal headers, and external headers.

The internal headers are only used while compiling the library,

the external headers (gl.h, zfeatures.h, zbuffer.h) are required to use the library.

You CAN compile the library along with your final program into a single compilation unit without separating out the library.

Doing so is the most likely compiling method for embedded platforms and how I got TinyGL running on the 3DS.

The codebase uses very simple compiler flags to compile- in fact it will compile if you just compile all c files together

in the src/ directory.

You can compile the code yourself without makefiles using these directives:

# inside the src directory
gcc -O3 -c *.c 
ar rcs libTinyGL.a *.o
# the library is now compiled
cp libTinyGL.a ../lib
cd ..
cd SDL_Examples/
# build the menu demo
gcc -O3 menu.c -o menu -lSDL ../lib/libTinyGL.a -lm
# gears
gcc -O3 gears.c -o gears -lSDL ../lib/libTinyGL.a -lm

This is how you use TinyGL in a program:

//First you have to include
//(Note that you must either link against libTinyGL.a or compile it in the same compilation unit as your program)
#include "../include/GL/gl.h"
#include "../include/zbuffer.h"

/*
    Somewhere in your program...
*/

//Next, open a framebuffer.
//The "0" parameter is where you pass in a framebuffer pointer if you've already made one.
ZBuffer* frameBuffer = ZB_open(winSizeX, winSizeY, mode, 0);

//Tell TinyGL to initialize on that framebuffer
glInit(frameBuffer);

//Begin making TinyGL calls!

//When you want to copy to your target screen
//Pitch is the width of the target in bytes, or bytes per pixel times width;
ZB_copyFrameBuffer(frameBuffer, screen->pixels, screen->pitch);

//At the end of your application, when you want to clean up.
ZB_close(frameBuffer);
glClose();

Note that while you... can invoke ZB_Resize to resize the framebuffer, you really shouldn't. It isn't tested.

WHAT ARE THE MINIMUM REQUIREMENTS OF THIS LIBRARY?

SDL 1.2 is required to run most of the demos I've written, but if you don't have SDL you can still check out the library by compiling one of the "Raw Demos" which write their output to a file (At the time of writing this, only gears has been added.)

SDL is by no means required to compile or use this library. SDL is used as a reasonable means of displaying the output of TinyGL for testing.

(I also included some bonus libraries that work well with SDL in the SDL examples if you want to write games using TinyGL!) (Try compiling the demos with -D PLAY_MUSIC if you have mixer!)

There is no FILE* usage, or I/O outside of 'msghandling.c' so if you want to remove all stdio dependency, just stub out the calls there.

Multithreading support

OpenMP is used on supported platforms to multithread certain operations.

(OpenMP is also used in the math library (zmath.h and zmath.c) to explicitly force certain operations to be SIMD accelerated, so it is recommended that you compile the library with OpenMP support!)

These are the operations that are accelerated by multithreading:

Every scanline is drawn by a separate thread.

Every call of the function pointer is run by a separate thread.

Every scan line is copied by a separate thread.

Every scan line is copied by a separate thread.

Compile the library with -fopenmp to see them in action (default). They are used in the texture demo, make sure to add the argument -pp

You do not need a multithreaded processor to use TinyGL!

Performance Recommendations

it is recommended that for best performance you keep TinyGL on a separate thread from SDL, and to guard TinyGL's buffer with a mutex.

This is not done in the demos but you can test the... thickness of the SDL stack by invoking gears or helloworld with -nosdl

The framerate doubles.

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 unless specifically listed.

glDeleteList

An easier to use version of glDeleteLists. glDeleteLists is also implemented.

glSetEnableSpecular(int shouldenablespecular);

This function can be added to display lists.

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 as glPlotPixel calls, the text is not saved in a display list.

Is capable of rendering the entire 8 bit latin extended character set (7 bit ascii plus characters 0xa0 and onward...)

You can check how to embed non-standard characters in your strings in the gears demo.

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.

glGenBuffers, glDeleteBuffers, glBindBuffer (valid target: ARRAY_BUFFER), glBindBufferAsArray

Serverside buffers! Makes it a bit easier to do clientside array stuff at the moment. may be the site of future hardware acceleration.

Please look at the model.c demo to see how to use these functions. They function very similarly to their GL 2.0+ counterparts.

glPostProcess(GLuint (*postprocess)(GLint x, GLint y, GLuint pixel, GLushort z))

Fast, Multithreaded Postprocessing for TinyGL.

You simply send in a function pointer (The function's name) and glPostProcess does the heavy lifting

The return value is the pixel (ARGB or 5R6G5B depending on mode).

x and y are the screen coordinataes.

pixel is the current color value of the pixel, ARGB or 5R6G5B depending on mode.

z is TinyGL's internal Z buffer representation. Larger values are considered to be "in front" of smaller ones.

This function is multithreaded on supported platforms for maximum execution speed. It of course still works without multithreading, but

it will not be as fast.

Note that you may have to take special care to prevent race conditions when using multithreading with this function.

NEW glGet calls!!!

You can query glGetIntegerV with these new definitions

    GL_POLYGON_MAX_VERTEX = 0xf001,
    GL_MAX_BUFFERS = 0xf002,
    GL_TEXTURE_HASH_TABLE_SIZE = 0xf003,
    GL_MAX_TEXTURE_LEVELS = 0xf004,
    GL_MAX_SPECULAR_BUFFERS = 0xf005,
    GL_MAX_DISPLAY_LISTS = 0xf006,
    GL_ERROR_CHECK_LEVEL = 0xf007,
    GL_IS_SPECULAR_ENABLED = 0xf008,

to query the configuration of TinyGL.

TOGGLEABLE FEATURES

See include/zfeatures.h

This changes too often to maintain documentation here.

The compiletime test is now disabled by default since it may not be "liked" by some obscure compilers... you can enable it in GL/gl.h

//at the top of include/GL/gl.h
//Enable TinyGL's Compiletime Compatibility Test (Scroll down)
#define COMPILETIME_TINYGL_COMPAT_TEST 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.

The whole library was filled with memory leaks and read-past-by-one type errors, and they have been corrected.

Notorious bugs from the original that have been fixed

FULLY COMPATIBLE WITH RGBA!

The library is now able to be configured properly for RGBA rendering. Note that the output is actually ARGB 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:

#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

Todo: add updated benchmarks

OpenIMGUI Standard

TinyGL includes an implementation of the OpenIMGUI standard, visible in SDL_EXAMPLES/menu.c

it is a standards proposal I've created for cross-platform immediate mode GUIs as a replacement for common solutions like "imgui" and Nuklear, which have glaring flaws when discussing their portability.

Consider using it!

Here is the old description of TinyGL, saved for historical/attribution purposes:

I do not endorse or promote its contents, they are here for attribution only.

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:

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.

Architecture:

TinyGL is made up four main modules:

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:

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 !