981170fc19
492: Clean up specialization and simd r=kvark a=NNemec The current SIMD implementation is based on the deprecated "simd" package and requires the unstable feature "specialization". So far, this was handled by significant code duplication and added complexity, making everything harder to understand even when "simd" was not in use at all. In order to migrate from "simd" to "packed_simd" it appears valuable to first clean up the existing "simd" code, see what is still valuable and then see how to migrate. This change reduces duplication, introduces a clear distinction of the "simd" feature and the "specialization" feature and moves most "simd" related code into separate source files. The code is pure refactoring, keeping all functionality unchanged. Testing the "simd" feature requires the 1.32 toolchain and commenting out the glium dev dependency. With that all tests run successfully. Co-authored-by: Norbert Nemec <norbert@nemec-online.de> |
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| benches | ||
| src | ||
| tests | ||
| .gitignore | ||
| .travis.yml | ||
| build.rs | ||
| Cargo.toml | ||
| CHANGELOG.md | ||
| LICENSE | ||
| README.md | ||
cgmath-rs
A linear algebra and mathematics library for computer graphics.
The library provides:
- vectors:
Vector2,Vector3,Vector4 - square matrices:
Matrix2,Matrix3,Matrix4 - a quaternion type:
Quaternion - rotation matrices:
Basis2,Basis3 - angle units:
Rad,Deg - points:
Point2,Point3 - perspective projections:
Perspective,PerspectiveFov,Ortho - spatial transformations:
AffineMatrix3,Transform3
Not all of the functionality has been implemented yet, and the existing code is not fully covered by the testsuite. If you encounter any mistakes or omissions please let me know by posting an issue, or even better: send me a pull request with a fix.
Conventions
cgmath interprets its vectors as column matrices (also known as "column vectors"), meaning when transforming a vector with a matrix, the matrix goes on the left. This is reflected in the fact that cgmath implements the multiplication operator for Matrix * Vector, but not Vector * Matrix.
Features
Swizzling
This library offers an optional feature called
"swizzling"
widely familiar to GPU programmers. To enable swizzle operators, pass the
--features="swizzle" option to cargo. Enabling this feature will increase
the size of the cgmath library by approximately 0.6MB. This isn't an
issue if the library is linked in the "normal" way by adding cgmath as a
dependency in Cargo.toml, which will link cgmath statically so all unused
swizzle operators will be optimized away by the compiler in release mode.
Example
If we have
let v = Vector3::new(1.0, 2.0, 3.0);
then v.xyxz() produces a
Vector4 { x: 1.0, y: 2.0, z: 1.0, w: 3.0 }
and v.zy() produces a
Vector2 { x: 3.0, y: 2.0 }
SIMD optimizations
The current SIMD support depends on the deprecated "simd" package as well as the unstable "specialization" feature. To build this code, a pre-1.33 nightly build of Rust is required, e.g. 2019-01-01-nightly. Though the code is not useful in its present form, it has some worth preserving as starting point for a future migration (see https://github.com/rustgd/cgmath/issues/490).
Limitations
cgmath is not an n-dimensional library and is aimed at computer graphics applications rather than general linear algebra. It only offers the 2, 3, and 4 dimensional structures that are more than enough for most computer graphics applications. This design decision was made in order to simplify the implementation (Rust cannot parameterize over constants at compile time), and to make dimension-specific optimisations easier in the future.
Contributing
Pull requests are most welcome, especially in the realm of performance enhancements and fixing any mistakes I may have made along the way. Unit tests and benchmarks are also required, so help on that front would be most appreciated.
Support
Contact bjz on irc.mozilla.org #rust
and #rust-gamedev,
or post an issue on Github.