Missing serialization support for Mat2/Mat3/Mat4

[repi]

Was experimenting with glam as a potential replacement for us for nalgebra-glm and one of the first issues I ran into was that the Mat2, Mat3 and Mat4 types was missing serde serialization support.

Currently it is only implemented for Vec2, Vec3, Vec4 and Quat in glam_serde.rs but likely shouldn't be too hard to add support for matrix types as well?.

[bitshifter]

It should be pretty easy. I'm traveling at the moment so might not get a chance to take a look until I get back home in a weeks time.

[repi]

np, thanks for the quick response. I'll give it a stab

[bitshifter]

Actually maybe it's not as straight forward as I thought, I thought these might just be able to use #[derive(Serialize, Deserialize)] but for consistency between the different types it might be better to implement these traits. I've started a branch at https://github.com/bitshifter/glam-rs/tree/matn_serde but it's not really useful yet.

Do you know what nalgebra_glm matrix types look like when they're serde json serialized?

I'm thinking either [m1, m2, m3, m4] or [[m1, m2],[m3,m4]] for a Mat2. The latter is more verbose but more obviously a matrix. I tend to try match what the equivalent of

#[derive(Serialize, Deserialize)]
struct Mat2(Vec2, Vec2)

would be serialized as, which is probably the latter.

[repi]

In my implementation I implemented the serialization explicit and serialized the matrices as flat arrays, thought it was a bit cleaner and potentially faster with less verbose output.

Checked up on how nalgebra-glm was serializing it and it was also doing it as a flat array of values instead of tuples:

Code:

   let m2 = glm::mat2(1.0, 2.0, 3.0, 4.0);
   let m3 = glm::mat3(1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0);
   let m4 = glm::mat4(1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0);
   println!("mat2: {}", serde_json::to_string(&m2).unwrap());
   println!("mat3: {}", serde_json::to_string(&m3).unwrap());
   println!("mat4: {}", serde_json::to_string(&m4).unwrap());

Output:

mat2: [1.0,3.0,2.0,4.0]
mat3: [1.0,4.0,7.0,2.0,5.0,8.0,3.0,6.0,9.0]
mat4: [1.0,5.0,9.0,13.0,2.0,6.0,10.0,14.0,3.0,7.0,11.0,15.0,4.0,8.0,12.0,16.0]

So I think that is the way to go.

I'll bring over your tests to my branch as well and do a PR!