Graphene

A thin layer of types for graphic libraries

When creating graphic libraries you most likely end up dealing with points and rectangles. If you're particularly unlucky, you may end up dealing with affine matrices and 2D transformations. If you're writing a graphic library with 3D transformations, though, you are going to hit the jackpot: 4x4 matrices, projections, transformations, vectors, and quaternions.

Most of this stuff exists, in various forms, in other libraries, but it has the major drawback of coming along with the rest of those libraries, which may or may not be what you want. Those libraries are also available in various languages, as long as those languages are C++; again, it may or may not be something you want.

For this reason, I decided to write the thinnest, smallest possible layer needed to write a canvas library; given its relative size, and the propensity for graphics libraries to have a pun in their name, I decided to call it Graphene.

This library provides types and their relative API; it does not deal with windowing system surfaces, drawing, scene graphs, or input. You're supposed to do that yourself, in your own canvas implementation, which is the whole point of writing the library in the first place.

Dependencies

Graphene has little dependencies.

Graphene contains optimizations for speeding up vector operations; those optimizations are optional, and used only if both Graphene was compiled with support for them and if the system you're running on has them. Currently, Graphene supports the following platform-specific fast paths:

• Streaming SIMD Extensions (SSE) 2
• ARM NEON
• GCC vector extensions

In the remote case in which none of these optimizations are available, Graphene will fall back to a naive scalar implementation.

Graphene can, optionally, provide types for integrating with GObject properties and signals, as well as introspection information for its use with other languages through introspection-based bindings.

Installation

In order to build and install Graphene you will need development tools and the headers of the dependencies.

First of all, clone the Git repository:

$ git clone git://github.com/ebassi/graphene
$ cd graphene

Then run:

$ ./autogen.sh
$ make
$ make check
# make install

It is possible, when building Graphene, to disable specific optimizations by passing options to the configure script:

• --disable-sse2 - will disable the SSE2 fast paths
• --disable-arm-neon - will disable the ARM NEON fast paths
• --disable-gcc-vector - will disable the GCC vector intrinsics

If you don't plan on generating introspection data, use --disable-introspection when configuring Graphene; similarly, if you don't plan on using GObject with Graphene, use --disable-gobject-types. Disabling GObject types will also automatically disable generating introspection data.

You can also disable building the test suite and the benchmark suite, using the --disable-tests and --disable-benchmarks configuration switches respectively.

See the output of configure --help for more information on the available configuration switches and environment variables.

Installing on Windows

In order to build on Windows, it's recommended to use the MSYS2 environment.

First, install MSYS2

Then, use pacman to set up the build environment, by installing the necessary prerequisites:

$ pacman -Sy
$ pacman -S automake
$ pacman -S autoconf
$ pacman -S libtool
$ pacman -S pkg-config
$ pacman -S gtk-doc
$ pacman -S make

Then, clone the Graphene repository and build as usual by following the instructions in the section above.

Contributing

If you found a bug (which I'm sure there will be plenty), or if you want to add your own pet feature, then follow these steps:

1. Fork the ebassi/graphene repo
2. Fix bugs or add new features and push them to your clone
3. Open a new issue
4. Open a pull request
5. Wait for me to give feedback on the pull request
6. Celebrate when your code gets merged

That's pretty much it.

Please, respect the coding style when writing patches for Graphene. The coding style can be immediately gleaned from the existing code, but here is a short version:

• Indentation is made of spaces, and only spaces — no tabs
• Each indentation level is 2 spaces
• Curly braces for blocks go on a separate indentation level
• Except for functions
• Do not use curly braces for single-statement blocks
• When declaring or defining a function, arguments go on separate lines
• When calling a function never break a line between the function name and the opening parenthesis, and between the opening parenthesis and the first argument
• Leave a space between functions and parenthesis

A more comprehensive coding style document is available in the docs directory.

Documentation

Available types

Graphene provides common types needed to handle 3D transformations:

• 2D points
• 3D points
• triangles
• rectangles
• quads
• quaternions
• euler angles
• vectors (2, 3, or 4-sized)
• matrices
• planes
• 3D boxes
• spheres
• frustums

Graphene also provides its low-level SIMD vector and matrix types, which are used to implement the API above.

All types can be placed on the stack, but provide allocation/free functions for working on the heap as well. The contents of all structure types, unless noted otherwise, should be considered private, and should never be accessed directly.

The full API reference for the for Graphene is available online.

License

Graphene is released under the terms of the MIT/X11 license.

See the LICENSE file for more details.