Add determinant to Transform2D

[Ughuuu]

Would be nice to have this function. It's also available and public in Godot, as can be seen here: Transform2D. Also, the function can be used to check for Transform2D invalid so that you don't call eg. affine_inverse on an invalid matrix and get an assert.

[GodotRust]

API docs are being generated and will be shortly available at: https://godot-rust.github.io/docs/gdext/pr-770

[Bromeon]

Thanks a lot!

[Ughuuu]

Enabled the actions on my fork to see how to fix the CI. will write here when I have it passing.

[Ughuuu]

Hm, not sure why the test fails. Any idea how to run it locally?

[lilizoey]

Hm, not sure why the test fails. Any idea how to run it locally?

Since it's a 4.0 godot test failing, the best way i think is to:

1. Grab a 4.0 godot binary
2. Run cargo build --p itest --features="godot/api-custom" with GODOT4_BIN pointing to the 4.0 godot binary
3. Go into itest/godot
4. Run godot4 --headless

It may be possible to use ./check.sh itest with GODOT4_BIN pointing to the right binary, but i've found the above more reliable. but feel free to try it

[Bromeon]

It's not necessary to run on Godot 4.0.

The error is very clear:

error[E0599]: no method named `determinant` found for struct `InnerTransform2D` in the current scope
  --> itest/rust/src/builtin_tests/geometry/transform2d_test.rs:44:30
   |
44 |         real::from_f64(inner.determinant()),
   |                              ^^^^^^^^^^^ method not found in `InnerTransform2D<'_>`

Then, navigate to Godot 4 Transform2D docs to confirm.
And you'll see that indeed, determinant() is missing. I has only been added later.

---

I'm fine to just add it for newer Godot versions. You can do this with #[cfg(since_api = "4.1")], as the method is available from 4.1.

Please also squash your commits and make sure there's a newline at the end of the .gitignore.

[Ughuuu]

Oh, so that was it, thanks, thats perfect. Didn't think it would be that simple, thought I had some configuration issue.

[fpdotmonkey]

FYI you can add this to your ~/.gitconfig to avoid needing to add this to every project's .gitignore

[core]
	excludesfile = /home/<USER>/.gitignore

[fpdotmonkey]

And then populate ~/.gitignore with the relevant ignores