Collection of math adapters to decouple your application from math libraries' implementations and to provide both inter-libraries compatibility and affordable exchangeability.
Been decoupled from concrete implementation of math library is useful. It make possible to interchange them and leverage interoperability between them.
Currently, as beck-end you may choose either cgmath or nalgebra and both math libs are integrated into the crate. Despite that, by default, math_adapter does not include neither of them and does not increase size of executable by unnecessary dependencies. To chose back-end use features:
cgmath - use cgmath as backendcgmath_ops - use cgmath as backend and make adapters to derefer to its functions and operatorsnalgebra - use nalgebra as backendnalgebra_ops - use nalgebra as backend and make adapters to derefer to its functions and operatorsSeveral math libs can be used, but functions and operators of only one should be used implicitly. Even if no *_ops feature is selected it is always an option to use functions and operators of math lib of choice explicitly.
To make explicit conversion use methods clone_as_cgmath(), clone_as_nalgebra(). To make explicit conversion into selected with feature *_ops use clone_as_foreign(). In this case dereferencing works as reinterpretation. Either adapter or foreign math object may be converted/reinterpreted into analog.
In the future each back-end is going to reside in an individual crate.
For example to use nalgebra with operators and its function include math_adapter like that:
toml
math_adapter = { version = "*", features = [ "nalgebra_ops" ] }
Each math libraries define its own versions of math objects. In most cases they have the same layout, but even if so compiler treat them as different. math_adapter provide such math objects too as well as means to either convert or reinterpret from foreign analogs. Among such are:
To apply functions from another library you may either convert or reinterpret math object. What is difference?
Reinterpretation take place during compile-time. Reinterpretation is possible if layout( size, alignment, padding and order ) of two similar structures are the same. For example structures cgmath::Vector2 and nalgebra::Vector2 are different structures, but them both have exactly same layout. That's why it's safe to reinterpret one to another and vise-versa. Reinterpretation says compiler to use one data structure as if it was another. It has zero run-time and compile-time cost. Such methods as as_foreign(), as_foreign_mut(), as_cgmath(), as_cgmath_mut(), as_nalgebra(), as_nalgebra_mut() reintepret math objects.
Conversion is different. Conversion says to rebuild a new instance of structure from components of another. It has non-zero run-time and compile-time cost. Although it is often optimized into reinterpretation by compiler. Using conversion instead of reinterpretation is safer. Thing is reinterpretation is safe based on several assumption about layout, which may be changed by either an author of a math library or by authors of the compiler. In theory! On practice it is unlikely. Even more most math libraries dedfine objects with #[ repr( C ) ], what restricts layout of such structures and protects them from changes in the future.
Every structure could be converted into another semantically similar structure even with different layout, but reinterpreation is possible only in case of the same layour. Because of that severa traits are implemented.
*NominalInterface - interface exposing function to convert and to access elements.*BasicInterface - interface extending X2NominalInterface and exposing functions to make a new instance of such.*CanonicalInterface - interface extending X2BasicInterface and exposing functions of reinterpretation.Relation: Canonical > Basic > Nominal.
Number of elements of a vector is coded in name of type, X2 for vector of length 2, X3 for vector of length 3 and so on. Each structure implements constructors make(), make_nan(), and make_default() to construct a new instance of the type. To get access to elements use either methods x(), y(), z() or _0(), _1(), _2().
```rust use mathadapter::prelude::*; use mathadapter::X2;
fn main() {
// vector of length 2 and its elements let src1 = X2::make( 1, 3 ); asserteq!( src1.x(), 1 ); asserteq!( src1.y(), 3 ); asserteq!( src1.0(), 1 ); asserteq!( src1.1(), 3 );
}
```
Select a feature *_ops to reuse operators and function of math lib of choice.
```rust use mathadapter::prelude::*; use mathadapter::X2;
fn main() {
// if back-end math lib is chosen then operators and functions are available #[ cfg( feature = "cgmathops" ) ] { let src1 = X2::make( 1, 2 ); let src2 = X2::make( 3, 4 ); let got = src1 + src2; let exp = X2::make( 4, 6 ); asserteq!( got, exp ); println!( "src1 + src2 : {:?}", got ); }
// enable feature _ops to get access to functions
#[ cfg( feature = "cgmath_ops" ) ]
{
let src = X2::make( 1, 2 );
assert_eq!( src.sum(), 3 ); / sum comes from cgmath */
println!( "src.sum() : {:?}", src.sum() );
}
} ```
Feature *_ops means to request to use operators and function of math lib of choice. But instead of choosing a single back-end math lib, you may use several. Use methods as_*_clone(), as_*, as_*_mut to either convert or reinterpret original math object into analog of such of chosen back-end. You don't have to use the same back-end in every call, you may choose which math lib for a specific call and combine the best of each math lib.
```rust use mathadapter::prelude::*; use mathadapter::X2;
fn main() {
// ! compile time error, because if no *_ops feature was chosen
// {
// let src = X2::make( 1, 3 ); /* make a canonical 2D vector /
// println!( "src.sum() : {:?}", src.sum() ); / use sum() of chosen math lib back-end */
// }
// enable feature _ops should be enabled to get access to functions
#[ cfg( all( feature = "cgmath", feature = "nalgebra" ) ) ]
{
let src = X2::make( 1, 3 ); / make a canonical 2D vector /
println!( "src.as_cgmath().sum() : {:?}", src.as_cgmath().sum() ); / use sum() of cgmath /
println!( "src.as_nalgebra().sum() : {:?}", src.as_nalgebra().sum() ); / use sum() of nalgebra */
}
// you can convert / reinterpret any vector.
// for example you can create cgmath::Vector2, but apply a function of nalgebra::Vector2
#[ cfg( all( feature = "cgmath", feature = "nalgebra" ) ) ]
{
let src = mathadapter::cgmath::Vector2::< i32 >::make( 1, 3 ); /* make a cgmath 2D vector */
println!( "src.asnalgebra().sum() : {:?}", src.as_nalgebra().sum() ); /* use sum() of nalgebra */
}
} ```
sh
cargo add math_adapter
sh
git clone https://github.com/Wandalen/wMath
cd wMath
cd module/math_adapter/sample/rust/math_adapter_trivial
cargo run