Choice of hex tile size in examples prevents pixel-perfect tiling

[ulfhermann]

The hex tiles are 15x17 pixels. Since when hex-tiling the rows or columns are offset by half a tile and neither the width nor the height are integer-divisible by 2, you necessarily get a pattern where every other "column" or "row" looks somewhat off. It took me a while to figure out that this was not some rendering deficiency but simply a matter of choosing even numbers for the sizes.

[ulfhermann]

An important information to be considered in this context is that bevy automatically calculates a scale factor for each window, which may be something like 1.08333 if you have exotically sized screens. You can override that thing:

app.add_plugins(
            DefaultPlugins
                .set(WindowPlugin {
                    primary_window: Some(Window {
                        title: String::from("Hexagon Column Example"),
                        resolution: WindowResolution::default().with_scale_factor_override(1.0),
                        ..Default::default()
                    }),
                    ..default()
                })...

Furthermore, you probably want to turn off anti-aliasing:

app.insert_resource(Msaa::Off);

I'm preparing a patch that gets rid of the sqrt(3) calculations and rather calculates the tile offsets from the given grid size using divisions by 2 and 4. That way a nicer grid size (like 28x32, for example) actually has an effect. If you do the sqrt(3) calculations, the calculation errors add up and your pixels will still be "off" in some places.