bevy/examples/3d/orthographic.rs
Alice Cecile 2bd328220b
Improve API for scaling orthographic cameras (#15969)
# Objective

Fixes #15791.

As raised in #11022, scaling orthographic cameras is confusing! In Bevy
0.14, there were multiple completely redundant ways to do this, and no
clear guidance on which to use.

As a result, #15075 removed the `scale` field from
`OrthographicProjection` completely, solving the redundancy issue.

However, this resulted in an unintuitive API and a painful migration, as
discussed in #15791. Users simply want to change a single parameter to
zoom, rather than deal with the irrelevant details of how the camera is
being scaled.

## Solution

This PR reverts #15075, and takes an alternate, more nuanced approach to
the redundancy problem. `ScalingMode::WindowSize` was by far the biggest
offender. This was the default variant, and stored a float that was
*fully* redundant to setting `scale`.

All of the other variants contained meaningful semantic information and
had an intuitive scale. I could have made these unitless, storing an
aspect ratio, but this would have been a worse API and resulted in a
pointlessly painful migration.

In the course of this work I've also:

- improved the documentation to explain that you should just set `scale`
to zoom cameras
- swapped to named fields for all of the variants in `ScalingMode` for
more clarity about the parameter meanings
- substantially improved the `projection_zoom` example
- removed the footgunny `Mul` and `Div` impls for `ScalingMode`,
especially since these no longer have the intended effect on
`ScalingMode::WindowSize`.
- removed a rounding step because this is now redundant 🎉 

## Testing

I've tested these changes as part of my work in the `projection_zoom`
example, and things seem to work fine.

## Migration Guide

`ScalingMode` has been refactored for clarity, especially on how to zoom
orthographic cameras and their projections:

- `ScalingMode::WindowSize` no longer stores a float, and acts as if its
value was 1. Divide your camera's scale by any previous value to achieve
identical results.
- `ScalingMode::FixedVertical` and `FixedHorizontal` now use named
fields.

---------

Co-authored-by: MiniaczQ <xnetroidpl@gmail.com>
2024-10-17 17:50:06 +00:00

59 lines
1.9 KiB
Rust

//! Shows how to create a 3D orthographic view (for isometric-look games or CAD applications).
use bevy::{prelude::*, render::camera::ScalingMode};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.run();
}
/// set up a simple 3D scene
fn setup(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
) {
// camera
commands.spawn((
Camera3d::default(),
Projection::from(OrthographicProjection {
// 6 world units per pixel of window height.
scaling_mode: ScalingMode::FixedVertical {
viewport_height: 6.0,
},
..OrthographicProjection::default_3d()
}),
Transform::from_xyz(5.0, 5.0, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
));
// plane
commands.spawn((
Mesh3d(meshes.add(Plane3d::default().mesh().size(5.0, 5.0))),
MeshMaterial3d(materials.add(Color::srgb(0.3, 0.5, 0.3))),
));
// cubes
commands.spawn((
Mesh3d(meshes.add(Cuboid::default())),
MeshMaterial3d(materials.add(Color::srgb(0.8, 0.7, 0.6))),
Transform::from_xyz(1.5, 0.5, 1.5),
));
commands.spawn((
Mesh3d(meshes.add(Cuboid::default())),
MeshMaterial3d(materials.add(Color::srgb(0.8, 0.7, 0.6))),
Transform::from_xyz(1.5, 0.5, -1.5),
));
commands.spawn((
Mesh3d(meshes.add(Cuboid::default())),
MeshMaterial3d(materials.add(Color::srgb(0.8, 0.7, 0.6))),
Transform::from_xyz(-1.5, 0.5, 1.5),
));
commands.spawn((
Mesh3d(meshes.add(Cuboid::default())),
MeshMaterial3d(materials.add(Color::srgb(0.8, 0.7, 0.6))),
Transform::from_xyz(-1.5, 0.5, -1.5),
));
// light
commands.spawn((PointLight::default(), Transform::from_xyz(3.0, 8.0, 5.0)));
}