matrix + vector types

[lcnr]

This crate currently uses [[f32; 4]; 4] as a 4x4 Matrix and (f32, f32, f32, f32) as a 4 component vector. This is simple and should be usable with any algebra / mathematics crate.

It does however prevent matrix and vector multiplication and addition, which is kind of annoying.

I am currently considering the following posibilities:

• keep using these simple types and add some helper methods like fn mat_mul.
• add matrix and vector types and implement the basic operations.
• use an existing algebra crate, while this seems like the best option, there are some disadvantages:
  • increases compilation time by ~25 % (nalgebra)
  • forces the user to use this crate, even if they want to use another one.
  • 2d pixel art games rarely need a lot of complex algebra so the additional complexity is not really worth it imo.

[lcnr]

Note: both [[f32; 4]; 4] and (f32, f32, f32, f32) is only used when dealing with colors,
as all positions are based on integers.

[MoarChan]

Vector types with methods, you mean like basic trigonometry?

[lcnr]

jup. To get a color_modulation matrix for a simple color one has to use something like this:

crow/examples/rectangles.rs

Lines 122 to 129 in 4449983

 fn mat((r, g, b): (f32, f32, f32)) -> [[f32; 4]; 4] { 
     [ 
         [r, 0.0, 0.0, 0.0], 
         [0.0, g, 0.0, 0.0], 
         [0.0, 0.0, b, 0.0], 
         [0.0, 0.0, 0.0, 1.0], 
     ] 
 } 

If we added a matrix + vector type this would just be identity_mat * color_vec which is a lot nicer.
To get an image which is toned red, one can use RED multiplied with GREYSCALE
As this is only relevant when depending on color_modulation I don't want to add too much complexity + compile time for this.

[MoarChan]

Could we add nalgebra as a default, but have an opt out feature like:
crow = { version = "x", features = ["no_nalgebra"]}

[lcnr]

you can enclose code segements with ``` to prevent the default text formatting.

crow = { version = "x", features = ["no_nalgebra"]}

which makes things a lot clearer.

Afaik this does not work well. features in rust should be additive and not break code.
I would like to allow e.g. GRAYSCALE * a_very_nice_color to work without requring explicit conversions.
This prob means changing the type of GRAYSCALE to nalgebras matrix type. This means that GRAYSCALE has a different type depending on the active feature. Thereby breaking any used library which also uses these consts but don't have the same active features.

I also kind of dislike nalgebra tbh 😆 That's just personal preference though