Add examples for orthographic and perspective zoom (#15092)

# Objective

Add examples for zooming (and orbiting) orthographic and perspective
cameras.

I'm pretty green with 3D, so please treat with suspicion! I note that
if/when #15075 is merged, `.scale` will go away so this example uses
`.scaling_mode`.

Closes #2580
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Rich Churcher 2024-09-10 11:30:52 +12:00 committed by GitHub
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commit b9b43ad89c
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@ -3244,6 +3244,18 @@ description = "A first-person camera that uses a world model and a view model wi
category = "Camera"
wasm = true
[[example]]
name = "projection_zoom"
path = "examples/camera/projection_zoom.rs"
doc-scrape-examples = true
[package.metadata.example.projection_zoom]
name = "Projection Zoom"
description = "Shows how to zoom and orbit orthographic and perspective projection cameras."
category = "Camera"
wasm = true
[package.metadata.example.fps_overlay]
name = "FPS overlay"
description = "Demonstrates FPS overlay"

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@ -255,6 +255,7 @@ Example | Description
--- | ---
[2D top-down camera](../examples/camera/2d_top_down_camera.rs) | A 2D top-down camera smoothly following player movements
[First person view model](../examples/camera/first_person_view_model.rs) | A first-person camera that uses a world model and a view model with different field of views (FOV)
[Projection Zoom](../examples/camera/projection_zoom.rs) | Shows how to zoom and orbit orthographic and perspective projection cameras.
## Dev tools

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@ -0,0 +1,245 @@
//! Shows how to zoom and orbit orthographic and perspective projection cameras.
use std::{
f32::consts::{FRAC_PI_2, PI},
ops::Range,
};
use bevy::{input::mouse::AccumulatedMouseScroll, prelude::*, render::camera::ScalingMode};
#[derive(Debug, Default, Resource)]
struct CameraSettings {
pub orbit_distance: f32,
// Multiply keyboard inputs by this factor
pub orbit_speed: f32,
// Clamp fixed vertical scale to this range
pub orthographic_zoom_range: Range<f32>,
// Multiply mouse wheel inputs by this factor
pub orthographic_zoom_speed: f32,
// Clamp field of view to this range
pub perspective_zoom_range: Range<f32>,
// Multiply mouse wheel inputs by this factor
pub perspective_zoom_speed: f32,
// Clamp pitch to this range
pub pitch_range: Range<f32>,
}
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.init_resource::<CameraSettings>()
.add_systems(Startup, (setup, instructions))
.add_systems(Update, (orbit, switch_projection, zoom))
.run();
}
/// Set up a simple 3D scene
fn setup(
mut camera_settings: ResMut<CameraSettings>,
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
) {
// Perspective projections use field of view, expressed in radians. We would
// normally not set it to more than π, which represents a 180° FOV.
let min_fov = PI / 5.;
let max_fov = PI - 0.2;
// In orthographic projections, we specify sizes in world units. The below values
// are very roughly similar to the above FOV settings, in terms of how "far away"
// the subject will appear when used with FixedVertical scaling mode.
let min_zoom = 5.0;
let max_zoom = 150.0;
// Limiting pitch stops some unexpected rotation past 90° up or down.
let pitch_limit = FRAC_PI_2 - 0.01;
camera_settings.orbit_distance = 10.0;
camera_settings.orbit_speed = 1.0;
camera_settings.orthographic_zoom_range = min_zoom..max_zoom;
camera_settings.orthographic_zoom_speed = 1.0;
camera_settings.perspective_zoom_range = min_fov..max_fov;
// Changes in FOV are much more noticeable due to its limited range in radians
camera_settings.perspective_zoom_speed = 0.05;
camera_settings.pitch_range = -pitch_limit..pitch_limit;
commands.spawn((
Name::new("Camera"),
Camera3dBundle {
projection: OrthographicProjection {
scaling_mode: ScalingMode::FixedVertical(
camera_settings.orthographic_zoom_range.start,
),
..OrthographicProjection::default_3d()
}
.into(),
transform: Transform::from_xyz(5.0, 5.0, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
..default()
},
));
commands.spawn((
Name::new("Plane"),
PbrBundle {
mesh: meshes.add(Plane3d::default().mesh().size(5.0, 5.0)),
material: materials.add(StandardMaterial {
base_color: Color::srgb(0.3, 0.5, 0.3),
// Turning off culling keeps the plane visible when viewed from beneath.
cull_mode: None,
..default()
}),
..default()
},
));
commands.spawn((
Name::new("Cube"),
PbrBundle {
mesh: meshes.add(Cuboid::default()),
material: materials.add(Color::srgb(0.8, 0.7, 0.6)),
transform: Transform::from_xyz(1.5, 0.51, 1.5),
..default()
},
));
commands.spawn((
Name::new("Light"),
PointLightBundle {
transform: Transform::from_xyz(3.0, 8.0, 5.0),
..default()
},
));
}
fn instructions(mut commands: Commands) {
commands
.spawn((
Name::new("Instructions"),
NodeBundle {
style: Style {
align_items: AlignItems::Start,
flex_direction: FlexDirection::Column,
justify_content: JustifyContent::Start,
width: Val::Percent(100.),
..default()
},
..default()
},
))
.with_children(|parent| {
parent.spawn(TextBundle::from_section(
"Scroll mouse wheel to zoom in/out",
TextStyle::default(),
));
parent.spawn(TextBundle::from_section(
"W or S: pitch",
TextStyle::default(),
));
parent.spawn(TextBundle::from_section(
"A or D: yaw",
TextStyle::default(),
));
});
}
fn orbit(
mut camera: Query<&mut Transform, With<Camera>>,
camera_settings: Res<CameraSettings>,
keyboard_input: Res<ButtonInput<KeyCode>>,
time: Res<Time>,
) {
let mut transform = camera.single_mut();
let mut delta_pitch = 0.0;
let mut delta_yaw = 0.0;
if keyboard_input.pressed(KeyCode::KeyW) {
delta_pitch += camera_settings.orbit_speed;
}
if keyboard_input.pressed(KeyCode::KeyA) {
delta_yaw -= camera_settings.orbit_speed;
}
if keyboard_input.pressed(KeyCode::KeyS) {
delta_pitch -= camera_settings.orbit_speed;
}
if keyboard_input.pressed(KeyCode::KeyD) {
delta_yaw += camera_settings.orbit_speed;
}
// Incorporating the delta time between calls prevents this from being framerate-bound.
delta_pitch *= time.delta_seconds();
delta_yaw *= time.delta_seconds();
// Obtain the existing pitch, yaw, and roll values from the transform.
let (yaw, pitch, roll) = transform.rotation.to_euler(EulerRot::YXZ);
// Establish the new yaw and pitch, preventing the pitch value from exceeding our limits.
let pitch = (pitch + delta_pitch).clamp(
camera_settings.pitch_range.start,
camera_settings.pitch_range.end,
);
let yaw = yaw + delta_yaw;
transform.rotation = Quat::from_euler(EulerRot::YXZ, yaw, pitch, roll);
// Adjust the translation to maintain the correct orientation toward the orbit target.
transform.translation = Vec3::ZERO - transform.forward() * camera_settings.orbit_distance;
}
fn switch_projection(
mut camera: Query<&mut Projection, With<Camera>>,
camera_settings: Res<CameraSettings>,
keyboard_input: Res<ButtonInput<KeyCode>>,
) {
let mut projection = camera.single_mut();
if keyboard_input.just_pressed(KeyCode::Space) {
// Switch projection type
*projection = match *projection {
Projection::Orthographic(_) => Projection::Perspective(PerspectiveProjection {
fov: camera_settings.perspective_zoom_range.start,
..default()
}),
Projection::Perspective(_) => Projection::Orthographic(OrthographicProjection {
scaling_mode: ScalingMode::FixedVertical(
camera_settings.orthographic_zoom_range.start,
),
..OrthographicProjection::default_3d()
}),
}
}
}
fn zoom(
mut camera: Query<&mut Projection, With<Camera>>,
camera_settings: Res<CameraSettings>,
mouse_wheel_input: Res<AccumulatedMouseScroll>,
) {
let projection = camera.single_mut();
// Usually, you won't need to handle both types of projection. This is by way of demonstration.
match projection.into_inner() {
Projection::Orthographic(ref mut orthographic) => {
// Get the current scaling_mode value to allow clamping the new value to our zoom range.
let ScalingMode::FixedVertical(current) = orthographic.scaling_mode else {
return;
};
// Set a new ScalingMode, clamped to a limited range.
let zoom_level = (current
+ camera_settings.orthographic_zoom_speed * mouse_wheel_input.delta.y)
.clamp(
camera_settings.orthographic_zoom_range.start,
camera_settings.orthographic_zoom_range.end,
);
orthographic.scaling_mode = ScalingMode::FixedVertical(zoom_level);
}
Projection::Perspective(ref mut perspective) => {
// Adjust the field of view, but keep it within our stated range.
perspective.fov = (perspective.fov
+ camera_settings.perspective_zoom_speed * mouse_wheel_input.delta.y)
.clamp(
camera_settings.perspective_zoom_range.start,
camera_settings.perspective_zoom_range.end,
);
}
}
}