Add parallax support

[perlindgren]

A minor update to support Tiled parallax information.

The asset/tiled_parallax.tmx provides a map with three layers (Background, Middle, and Foreground), each with different parallax information (Middle being the default Tiled (1.0, 1.0)).

The tests/test contains an example:

fn test_parallax_layers() {
    let r = read_from_file_with_path(&Path::new("assets/tiled_parallax.tmx")).unwrap();
    for (i, layer) in r.layers.iter().enumerate() {
        match i {
            0 => {
                assert_eq!(layer.name, "Background");
                assert_eq!(layer.parallax_x, 0.5);
                assert_eq!(layer.parallax_y, 0.75);
            }
            1 => {
                assert_eq!(layer.name, "Middle");
                assert_eq!(layer.parallax_x, 1.0);
                assert_eq!(layer.parallax_y, 1.0);
            }
            2 => {
                assert_eq!(layer.name, "Foreground");
                assert_eq!(layer.parallax_x, 2.0);
                assert_eq!(layer.parallax_y, 2.0);
            }
            _ => panic!("unexpected layer"),
        }
    }
}

The version is bumped to 0.9.6 to indicate the extended information.

Thanks for a great crate by the way!

[bjorn]

@perlindgren These changes look good, but unfortunately conflict with the recent reorganization done in c386766. Could you rebase your additions?

Btw, this crate has recently moved to the @mapeditor organization so that we can share maintenance between those that use this crate. Let me know if you're interested in helping with further development!

[PieKing1215]

Just a note, this doesn't work on object layers as is.
You basically just need to copy the changes into objects.rs as well for it to work.

[perlindgren]

So I fixed it, since the changes were so few and small it was actually easier just to copy/paste my changes into the new repo structure (mainly its in the layers.rs.

@bjorn did you have anything in particular in mind regarding the repo development. I played around a bit with Rust Bevy, and implemented parallax scrolling there, but since the rs-tiled crate did not support parallax info extraction I just went for it.

[aleokdev]

Pretty good, there are just a few minor formatting issues.

[bjorn]

So I fixed it, since the changes were so few and small it was actually easier just to copy/paste my changes into the new repo structure (mainly its in the layers.rs).

That's great, thanks! What about also adjusting objects.rs as per @PieKing1215's comment? And of course these attributes also affect ImageLayer.

Or, rather than duplicating more stuff, we could merge this as-is for now (just addressing the minor code style adjustments) and instead look into refactoring the data structure into an enum? I think we can pretty much copy the structs from https://gitlab.com/flukejones/tiled-json-rs/-/blob/master/src/layer.rs#L79-112.

@bjorn did you have anything in particular in mind regarding the repo development. I played around a bit with Rust Bevy, and implemented parallax scrolling there, but since the rs-tiled crate did not support parallax info extraction I just went for it.

We'll need to make sure this crate supports all features of TMX and preferably also supports deserializing JSON. Secondly I think we need to make it more convenient to use, while keeping an eye on performance. Is that what you were asking?

[bjorn]

I've addressed the minor code style issues and merged master again. I think this can be squashed and merged now.

Regarding adding these to ObjectGroup and ImageLayer, I think we can do it in a separate change as mentioned earlier.

[aleokdev]

Add changelog changes and it's good to go

[bjorn]

I'm not sure why those newlines in assets/tiled_parallax.tmx changed again...

[aleokdev]

Sorry for being so late, the notification didn't get through.

[bjorn]

Sorry for being so late, the notification didn't get through.

No problem, it was good to wait with this until you were done with #131. :-)