mirror of
https://github.com/bevyengine/bevy
synced 2024-11-26 22:50:19 +00:00
7989cb2650
# Objective - Make `Time` API more consistent. - Support time accel/decel/pause. ## Solution This is just the `Time` half of #3002. I was told that part isn't controversial. - Give the "delta time" and "total elapsed time" methods `f32`, `f64`, and `Duration` variants with consistent naming. - Implement accelerating / decelerating the passage of time. - Implement stopping time. --- ## Changelog - Changed `time_since_startup` to `elapsed` because `time.time_*` is just silly. - Added `relative_speed` and `set_relative_speed` methods. - Added `is_paused`, `pause`, `unpause` , and methods. (I'd prefer `resume`, but `unpause` matches `Timer` API.) - Added `raw_*` variants of the "delta time" and "total elapsed time" methods. - Added `first_update` method because there's a non-zero duration between startup and the first update. ## Migration Guide - `time.time_since_startup()` -> `time.elapsed()` - `time.seconds_since_startup()` -> `time.elapsed_seconds_f64()` - `time.seconds_since_startup_wrapped_f32()` -> `time.elapsed_seconds_wrapped()` If you aren't sure which to use, most systems should continue to use "scaled" time (e.g. `time.delta_seconds()`). The realtime "unscaled" time measurements (e.g. `time.raw_delta_seconds()`) are mostly for debugging and profiling.
110 lines
4.1 KiB
Rust
110 lines
4.1 KiB
Rust
//! Demonstrates how to use transparency in 3D.
|
|
//! Shows the effects of different blend modes.
|
|
//! The `fade_transparency` system smoothly changes the transparency over time.
|
|
|
|
use bevy::prelude::*;
|
|
|
|
fn main() {
|
|
App::new()
|
|
.insert_resource(Msaa { samples: 4 })
|
|
.add_plugins(DefaultPlugins)
|
|
.add_startup_system(setup)
|
|
.add_system(fade_transparency)
|
|
.run();
|
|
}
|
|
|
|
fn setup(
|
|
mut commands: Commands,
|
|
mut meshes: ResMut<Assets<Mesh>>,
|
|
mut materials: ResMut<Assets<StandardMaterial>>,
|
|
) {
|
|
// opaque plane, uses `alpha_mode: Opaque` by default
|
|
commands.spawn(PbrBundle {
|
|
mesh: meshes.add(Mesh::from(shape::Plane { size: 6.0 })),
|
|
material: materials.add(Color::rgb(0.3, 0.5, 0.3).into()),
|
|
..default()
|
|
});
|
|
// transparent sphere, uses `alpha_mode: Mask(f32)`
|
|
commands.spawn(PbrBundle {
|
|
mesh: meshes.add(Mesh::from(shape::Icosphere {
|
|
radius: 0.5,
|
|
subdivisions: 3,
|
|
})),
|
|
material: materials.add(StandardMaterial {
|
|
// Alpha channel of the color controls transparency.
|
|
// We set it to 0.0 here, because it will be changed over time in the
|
|
// `fade_transparency` function.
|
|
// Note that the transparency has no effect on the objects shadow.
|
|
base_color: Color::rgba(0.2, 0.7, 0.1, 0.0),
|
|
// Mask sets a cutoff for transparency. Alpha values below are fully transparent,
|
|
// alpha values above are fully opaque.
|
|
alpha_mode: AlphaMode::Mask(0.5),
|
|
..default()
|
|
}),
|
|
transform: Transform::from_xyz(1.0, 0.5, -1.5),
|
|
..default()
|
|
});
|
|
// transparent unlit sphere, uses `alpha_mode: Mask(f32)`
|
|
commands.spawn(PbrBundle {
|
|
mesh: meshes.add(Mesh::from(shape::Icosphere {
|
|
radius: 0.5,
|
|
subdivisions: 3,
|
|
})),
|
|
material: materials.add(StandardMaterial {
|
|
base_color: Color::rgba(0.2, 0.7, 0.1, 0.0),
|
|
alpha_mode: AlphaMode::Mask(0.5),
|
|
unlit: true,
|
|
..default()
|
|
}),
|
|
transform: Transform::from_xyz(-1.0, 0.5, -1.5),
|
|
..default()
|
|
});
|
|
// transparent cube, uses `alpha_mode: Blend`
|
|
commands.spawn(PbrBundle {
|
|
mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
|
|
// Notice how there is no need to set the `alpha_mode` explicitly here.
|
|
// When converting a color to a material using `into()`, the alpha mode is
|
|
// automatically set to `Blend` if the alpha channel is anything lower than 1.0.
|
|
material: materials.add(Color::rgba(0.5, 0.5, 1.0, 0.0).into()),
|
|
transform: Transform::from_xyz(0.0, 0.5, 0.0),
|
|
..default()
|
|
});
|
|
// opaque sphere
|
|
commands.spawn(PbrBundle {
|
|
mesh: meshes.add(Mesh::from(shape::Icosphere {
|
|
radius: 0.5,
|
|
subdivisions: 3,
|
|
})),
|
|
material: materials.add(Color::rgb(0.7, 0.2, 0.1).into()),
|
|
transform: Transform::from_xyz(0.0, 0.5, -1.5),
|
|
..default()
|
|
});
|
|
// light
|
|
commands.spawn(PointLightBundle {
|
|
point_light: PointLight {
|
|
intensity: 1500.0,
|
|
shadows_enabled: true,
|
|
..default()
|
|
},
|
|
transform: Transform::from_xyz(4.0, 8.0, 4.0),
|
|
..default()
|
|
});
|
|
// camera
|
|
commands.spawn(Camera3dBundle {
|
|
transform: Transform::from_xyz(-2.0, 3.0, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
|
|
..default()
|
|
});
|
|
}
|
|
|
|
/// Fades the alpha channel of all materials between 0 and 1 over time.
|
|
/// Each blend mode responds differently to this:
|
|
/// - `Opaque`: Ignores alpha channel altogether, these materials stay completely opaque.
|
|
/// - `Mask(f32)`: Object appears when the alpha value goes above the mask's threshold, disappears
|
|
/// when the alpha value goes back below the threshold.
|
|
/// - `Blend`: Object fades in and out smoothly.
|
|
pub fn fade_transparency(time: Res<Time>, mut materials: ResMut<Assets<StandardMaterial>>) {
|
|
let alpha = (time.elapsed_seconds().sin() / 2.0) + 0.5;
|
|
for (_, material) in materials.iter_mut() {
|
|
material.base_color.set_a(alpha);
|
|
}
|
|
}
|