25bfa80e60
# Objective Yet another PR for migrating stuff to required components. This time, cameras! ## Solution As per the [selected proposal](https://hackmd.io/tsYID4CGRiWxzsgawzxG_g#Combined-Proposal-1-Selected), deprecate `Camera2dBundle` and `Camera3dBundle` in favor of `Camera2d` and `Camera3d`. Adding a `Camera` without `Camera2d` or `Camera3d` now logs a warning, as suggested by Cart [on Discord](https://discord.com/channels/691052431525675048/1264881140007702558/1291506402832945273). I would personally like cameras to work a bit differently and be split into a few more components, to avoid some footguns and confusing semantics, but that is more controversial, and shouldn't block this core migration. ## Testing I ran a few 2D and 3D examples, and tried cameras with and without render graphs. --- ## Migration Guide `Camera2dBundle` and `Camera3dBundle` have been deprecated in favor of `Camera2d` and `Camera3d`. Inserting them will now also insert the other components required by them automatically.
116 lines
4.4 KiB
Rust
116 lines
4.4 KiB
Rust
//! Demonstrates how to use transparency in 3D.
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//! Shows the effects of different blend modes.
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//! The `fade_transparency` system smoothly changes the transparency over time.
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use bevy::{math::ops, prelude::*};
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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.add_systems(Startup, setup)
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.add_systems(Update, fade_transparency)
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.run();
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}
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fn setup(
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mut commands: Commands,
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mut meshes: ResMut<Assets<Mesh>>,
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mut materials: ResMut<Assets<StandardMaterial>>,
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) {
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// Opaque plane, uses `alpha_mode: Opaque` by default
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commands.spawn((
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Mesh3d(meshes.add(Plane3d::default().mesh().size(6.0, 6.0))),
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MeshMaterial3d(materials.add(Color::srgb(0.3, 0.5, 0.3))),
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));
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// Transparent sphere, uses `alpha_mode: Mask(f32)`
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commands.spawn((
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Mesh3d(meshes.add(Sphere::new(0.5).mesh().ico(3).unwrap())),
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MeshMaterial3d(materials.add(StandardMaterial {
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// Alpha channel of the color controls transparency.
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// We set it to 0.0 here, because it will be changed over time in the
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// `fade_transparency` function.
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// Note that the transparency has no effect on the objects shadow.
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base_color: Color::srgba(0.2, 0.7, 0.1, 0.0),
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// Mask sets a cutoff for transparency. Alpha values below are fully transparent,
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// alpha values above are fully opaque.
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alpha_mode: AlphaMode::Mask(0.5),
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..default()
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})),
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Transform::from_xyz(1.0, 0.5, -1.5),
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));
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// Transparent unlit sphere, uses `alpha_mode: Mask(f32)`
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commands.spawn((
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Mesh3d(meshes.add(Sphere::new(0.5).mesh().ico(3).unwrap())),
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MeshMaterial3d(materials.add(StandardMaterial {
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base_color: Color::srgba(0.2, 0.7, 0.1, 0.0),
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alpha_mode: AlphaMode::Mask(0.5),
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unlit: true,
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..default()
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})),
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Transform::from_xyz(-1.0, 0.5, -1.5),
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));
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// Transparent cube, uses `alpha_mode: Blend`
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commands.spawn((
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Mesh3d(meshes.add(Cuboid::default())),
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// Notice how there is no need to set the `alpha_mode` explicitly here.
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// When converting a color to a material using `into()`, the alpha mode is
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// automatically set to `Blend` if the alpha channel is anything lower than 1.0.
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MeshMaterial3d(materials.add(Color::srgba(0.5, 0.5, 1.0, 0.0))),
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Transform::from_xyz(0.0, 0.5, 0.0),
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));
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// Transparent cube, uses `alpha_mode: AlphaToCoverage`
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commands.spawn((
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Mesh3d(meshes.add(Cuboid::default())),
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MeshMaterial3d(materials.add(StandardMaterial {
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base_color: Color::srgba(0.5, 1.0, 0.5, 0.0),
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alpha_mode: AlphaMode::AlphaToCoverage,
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..default()
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})),
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Transform::from_xyz(-1.5, 0.5, 0.0),
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));
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// Opaque sphere
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commands.spawn((
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Mesh3d(meshes.add(Sphere::new(0.5).mesh().ico(3).unwrap())),
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MeshMaterial3d(materials.add(Color::srgb(0.7, 0.2, 0.1))),
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Transform::from_xyz(0.0, 0.5, -1.5),
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));
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// Light
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commands.spawn((
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PointLight {
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shadows_enabled: true,
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..default()
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},
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Transform::from_xyz(4.0, 8.0, 4.0),
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));
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// Camera
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commands.spawn((
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Camera3d::default(),
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Transform::from_xyz(-2.0, 3.0, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
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));
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}
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/// Fades the alpha channel of all materials between 0 and 1 over time.
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/// Each blend mode responds differently to this:
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/// - [`Opaque`](AlphaMode::Opaque): Ignores alpha channel altogether, these materials stay completely opaque.
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/// - [`Mask(f32)`](AlphaMode::Mask): Object appears when the alpha value goes above the mask's threshold, disappears
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/// when the alpha value goes back below the threshold.
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/// - [`Blend`](AlphaMode::Blend): Object fades in and out smoothly.
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/// - [`AlphaToCoverage`](AlphaMode::AlphaToCoverage): Object fades in and out
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/// in steps corresponding to the number of multisample antialiasing (MSAA)
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/// samples in use. For example, assuming 8xMSAA, the object will be
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/// completely opaque, then will be 7/8 opaque (1/8 transparent), then will be
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/// 6/8 opaque, then 5/8, etc.
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pub fn fade_transparency(time: Res<Time>, mut materials: ResMut<Assets<StandardMaterial>>) {
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let alpha = (ops::sin(time.elapsed_seconds()) / 2.0) + 0.5;
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for (_, material) in materials.iter_mut() {
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material.base_color.set_alpha(alpha);
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}
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}
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