Creating a line shape on screen given two points.

[tyush]

Hi all,

I'm trying to use Bevy to create a 2D top-down style racing game. In order to generate the track, I'm using a set of (f32, f32) tuples in order to define a continuous "guardrail" for the track.

I think I have getting the line's center position, which I can set at the translation, length, and the line's rotation along the z axis down, but the code I use for that is below just in case.

let z_rot = ((self.1 - other.1) / (self.0 - other.0)).atan() * (180.0 / PI); // unit conversion: radians to euler degrees
let length = ((self.0 - other.0).powi(2) + (self.1 - other.1).powi(2)).sqrt();
let center_point = ((self.0 + other.0) / 2.0, (self.1 + other.1) / 2.0);

This is the code I have so far for generating a line:

fn from_len_deg(
    pos: (f32, f32),
    length: f32,
    rot: f32,
    color: Handle<ColorMaterial>,
    meshes: &mut ResMut<Assets<Mesh>>
) -> bevy::prelude::SpriteBundle {
    let mut transform = Transform::from_scale(Vec3::ONE);
    transform.translation = Vec3::new(pos.0, pos.1, 0.0);
    transform.rotation = Quat::from_rotation_z(rot);

    let sprite = SpriteBundle {
        material: color,
        mesh: meshes.add(Mesh::from(shape::Quad { size: Vec2::new(length, 1.0), flip: false })),
        sprite: Sprite::new(Vec2::new(length, 1.0)),
        transform, 
        ..Default::default()
    };

    sprite
}

This sounds right in my head, but running it produces weird results. Here's what the points [(0.0, 0.0), (10.0, 0.0), (20.0, 20.0), (30.0, 40.0)]

My guess is that the translation is not being updated properly, but inspecting the transforms during runtime by using the bevy-inspector-egui shows completely normal and expected values. Below is for the line from (0.0, 0.0) -> (10.0, 0.0).

Frankly, I'm starting to feel at my wit's end here. Is there anything that jumps out as a logic fault in terms of how I'm attempting to create these?

[tyush]

Hey guys, solved this myself by literally holding up a protractor to my screen and trial/erroring until something worked. A working-ish version is in this gist.
https://gist.github.com/tyush/07d72231e6f7cbe6fe9b6bc8c4e522f9