Crate glam[−][src]
glam
glam
is a simple and fast linear algebra library for games and graphics.
Features
glam
is built with SIMD in mind. Currently only SSE2 on x86/x86_64 is
supported as this is what stable Rust supports.
 Vector, quaternion and matrix types support for
f32
andf64
 Vector types supported for
i32
,u32
andbool
 SSE2 storage and optimization for many
f32
types, includingMat2
,Mat4
,Quat
,Vec3A
andVec4
 Scalar math fallback implementations exist when SSE2 is not available
 Most functionality includes unit tests and benchmarks
Linear algebra conventions
glam
interprets vectors as column matrices (also known as “column vectors”)
meaning when transforming a vector with a matrix the matrix goes on the left.
use glam::{Mat3, Vec3}; let m = Mat3::IDENTITY; let x = Vec3::X; let v = m * x; assert_eq!(v, x);
Matrices are stored in memory in columnmajor order.
Direct element access
Because some types may internally be implemeted using SIMD types, direct access to vector elements
is supported by implementing the Deref
and DerefMut
traits.
use glam::Vec3A; let mut v = Vec3A::new(1.0, 2.0, 3.0); assert_eq!(3.0, v.z); v.z += 1.0; assert_eq!(4.0, v.z);
Size and alignment of types
Some glam
types use SIMD for storage meaning they are 16 byte aligned, these
types include Mat2
, Mat4
, Quat
, Vec3A
and Vec4
.
When SSE2 is not available on the target architecture this type will still be 16 byte aligned so that object sizes and layouts will not change between architectures.
SIMD support can be disabled entirely using the scalarmath
feature. This
feature will also disable SIMD alignment meaning most types will use native
f32
alignment of 4 bytes.
All the main glam
types are #[repr(C)]
, so they are possible to expose as
struct members to C interfaces if desired. Be mindful of Vec3A’s extra padding
though.
Vec3A
Vec3A
is a SIMD optimized version of the Vec3
type, which due to 16 byte
alignment results in Vec3A
containing 4 bytes of padding making it 16 bytes
in size in total.
Type  f32 bytes  Align bytes  Padding  Size bytes 

Vec3  12  4  0  12 
Vec3A  12  16  4  16 
Despite this wasted space the SIMD version tends to outperform the f32
implementation in mathbench
benchmarks.
glam
treats Vec3
as the default vector 3 type and Vec3A
a special case for
optimization. When methods need to return a vector 3 type they will generally
return Vec3
.
There are From
trait implementations for converting from Vec4
to a Vec3A
and between Vec3
and Vec3A
(and vice versa).
use glam::{Vec3, Vec3A, Vec4}; let v4 = Vec4::new(1.0, 2.0, 3.0, 4.0); // Convert from `Vec4` to `Vec3A`, this is a noop if SIMD is supported. let v3a = Vec3A::from(v4); assert_eq!(Vec3A::new(1.0, 2.0, 3.0), v3a); // Convert from `Vec3A` to `Vec3`. let v3 = Vec3::from(v3a); assert_eq!(Vec3::new(1.0, 2.0, 3.0), v3); // Convert from `Vec3` to `Vec3A`. let v3a = Vec3A::from(v3); assert_eq!(Vec3A::new(1.0, 2.0, 3.0), v3a);
Vector swizzles
glam
vector types have functions allowing elements of vectors to be reordered,
this includes creating a vector of a different size from the vectors elements.
The swizzle functions are implemented using traits to add them to each vector
type. This is primarily because there are a lot of swizzle functions which can
obfuscate the other vector functions in documentation and so on. The traits are
Vec2Swizzles
, Vec3Swizzles
and Vec4Swizzles
.
Note that the Vec3Swizzles
implementation for Vec3A
will return a Vec3A
for 3 element swizzles, all other implementations will return Vec3
.
use glam::{swizzles::*, Vec2, Vec3, Vec3A, Vec4}; let v = Vec4::new(1.0, 2.0, 3.0, 4.0); // Reverse elements of `v`, if SIMD is supported this will use a vector shuffle. let wzyx = v.wzyx(); assert_eq!(Vec4::new(4.0, 3.0, 2.0, 1.0), wzyx); // Swizzle the yzw elements of `v` into a `Vec3` let yzw = v.yzw(); assert_eq!(Vec3::new(2.0, 3.0, 4.0), yzw); // To swizzle a `Vec4` into a `Vec3A` swizzle the `Vec4` first then convert to // `Vec3A`. If SIMD is supported this will use a vector shuffle. The last // element of the shuffled `Vec4` is ignored by the `Vec3A`. let yzw = Vec3A::from(v.yzwx()); assert_eq!(Vec3A::new(2.0, 3.0, 4.0), yzw); // You can swizzle from a `Vec4` to a `Vec2` let xy = v.xy(); assert_eq!(Vec2::new(1.0, 2.0), xy); // And back again let yyxx = xy.yyxx(); assert_eq!(Vec4::new(2.0, 2.0, 1.0, 1.0), yyxx);
SIMD and scalar consistency
glam
types implement serde
Serialize
and Deserialize
traits to ensure
that they will serialize and deserialize exactly the same whether or not
SIMD support is being used.
The SIMD versions implement the core::fmt::Debug
and core::fmt::Display
traits so they print the same as the scalar version.
use glam::Vec4; let a = Vec4::new(1.0, 2.0, 3.0, 4.0); assert_eq!(format!("{}", a), "[1, 2, 3, 4]");
Feature gates
All glam
dependencies are optional, however some are required for tests
and benchmarks.
std
 the default feature, has no dependencies.rand
 used to generate random values. Used in benchmarks.serde
 used for serialization and deserialization of types.mint
 used for interoperating with other linear algebra libraries.scalarmath
 disables SIMD support and uses native alignment for all types.debugglamassert
 adds assertions in debug builds which check the validity of parameters passed toglam
to help catch runtime errors.glamassert
 adds assertions to all builds which check the validity of parameters passed toglam
to help catch runtime errors.
Minimum Supported Version or Rust (MSVR)
The minimum supported version of Rust for glam
is 1.36.0
.
Reexports
pub use self::bool::*; 
pub use self::f32::*; 
pub use self::f64::*; 
pub use self::i32::*; 
pub use self::u32::*; 
Modules
bool 

f32 

f64 

i32 

swizzles  Traits adding swizzle methods to all vector types. 
u32 

Macros
const_dmat2  Creates a 
const_dmat3  Creates a 
const_dmat4  Creates a 
const_dquat  Creates a 
const_dvec2  Creates a 
const_dvec3  Creates a 
const_dvec4  Creates a 
const_ivec2  Creates a 
const_ivec3  Creates a 
const_ivec4  Creates a 
const_m128  
const_mat2  Creates a 
const_mat3  Creates a 
const_mat4  Creates a 
const_quat  Creates a 
const_uvec2  Creates a 
const_uvec3  Creates a 
const_uvec4  Creates a 
const_vec2  Creates a 
const_vec3  Creates a 
const_vec3a  Creates a 
const_vec4  Creates a 
Traits
Vec2Swizzles  Swizzle methods for 2dimensional vector types. 
Vec3Swizzles  Swizzle methods for 3dimensional vector types. 
Vec4Swizzles  Swizzle methods for 3dimensional vector types. 