# Motivation
When spawning entities into a scene, it is very common to create assets
like meshes and materials and to add them via asset handles. A common
setup might look like this:
```rust
fn setup(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
) {
commands.spawn(PbrBundle {
mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
material: materials.add(StandardMaterial::from(Color::RED)),
..default()
});
}
```
Let's take a closer look at the part that adds the assets using `add`.
```rust
mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
material: materials.add(StandardMaterial::from(Color::RED)),
```
Here, "mesh" and "material" are both repeated three times. It's very
explicit, but I find it to be a bit verbose. In addition to being more
code to read and write, the extra characters can sometimes also lead to
the code being formatted to span multiple lines even though the core
task, adding e.g. a primitive mesh, is extremely simple.
A way to address this is by using `.into()`:
```rust
mesh: meshes.add(shape::Cube { size: 1.0 }.into()),
material: materials.add(Color::RED.into()),
```
This is fine, but from the names and the type of `meshes`, we already
know what the type should be. It's very clear that `Cube` should be
turned into a `Mesh` because of the context it's used in. `.into()` is
just seven characters, but it's so common that it quickly adds up and
gets annoying.
It would be nice if you could skip all of the conversion and let Bevy
handle it for you:
```rust
mesh: meshes.add(shape::Cube { size: 1.0 }),
material: materials.add(Color::RED),
```
# Objective
Make adding assets more ergonomic by making `Assets::add` take an `impl
Into<A>` instead of `A`.
## Solution
`Assets::add` now takes an `impl Into<A>` instead of `A`, so e.g. this
works:
```rust
commands.spawn(PbrBundle {
mesh: meshes.add(shape::Cube { size: 1.0 }),
material: materials.add(Color::RED),
..default()
});
```
I also changed all examples to use this API, which increases consistency
as well because `Mesh::from` and `into` were being used arbitrarily even
in the same file. This also gets rid of some lines of code because
formatting is nicer.
---
## Changelog
- `Assets::add` now takes an `impl Into<A>` instead of `A`
- Examples don't use `T::from(K)` or `K.into()` when adding assets
## Migration Guide
Some `into` calls that worked previously might now be broken because of
the new trait bounds. You need to either remove `into` or perform the
conversion explicitly with `from`:
```rust
// Doesn't compile
let mesh_handle = meshes.add(shape::Cube { size: 1.0 }.into()),
// These compile
let mesh_handle = meshes.add(shape::Cube { size: 1.0 }),
let mesh_handle = meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
```
## Concerns
I believe the primary concerns might be:
1. Is this too implicit?
2. Does this increase codegen bloat?
Previously, the two APIs were using `into` or `from`, and now it's
"nothing" or `from`. You could argue that `into` is slightly more
explicit than "nothing" in cases like the earlier examples where a
`Color` gets converted to e.g. a `StandardMaterial`, but I personally
don't think `into` adds much value even in this case, and you could
still see the actual type from the asset type.
As for codegen bloat, I doubt it adds that much, but I'm not very
familiar with the details of codegen. I personally value the user-facing
code reduction and ergonomics improvements that these changes would
provide, but it might be worth checking the other effects in more
detail.
Another slight concern is migration pain; apps might have a ton of
`into` calls that would need to be removed, and it did take me a while
to do so for Bevy itself (maybe around 20-40 minutes). However, I think
the fact that there *are* so many `into` calls just highlights that the
API could be made nicer, and I'd gladly migrate my own projects for it.
Links in the api docs are nice. I noticed that there were several places
where structs / functions and other things were referenced in the docs,
but weren't linked. I added the links where possible / logical.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: François <mockersf@gmail.com>
# Objective
There was issue #191 requesting subdivisions on the shape::Plane.
I also could have used this recently. I then write the solution.
Fixes #191
## Solution
I changed the shape::Plane to include subdivisions field and the code to create the subdivisions. I don't know how people are counting subdivisions so as I put in the doc comments 0 subdivisions results in the original geometry of the Plane.
Greater then 0 results in the number of lines dividing the plane.
I didn't know if it would be better to create a new struct that implemented this feature, say SubdivisionPlane or change Plane. I decided on changing Plane as that was what the original issue was.
It would be trivial to alter this to use another struct instead of altering Plane.
The issues of migration, although small, would be eliminated if a new struct was implemented.
## Changelog
### Added
Added subdivisions field to shape::Plane
## Migration Guide
All the examples needed to be updated to initalize the subdivisions field.
Also there were two tests in tests/window that need to be updated.
A user would have to update all their uses of shape::Plane to initalize the subdivisions field.
# Objective
Fixes#6931
Continues #6954 by squashing `Msaa` to a flat enum
Helps out #7215
# Solution
```
pub enum Msaa {
Off = 1,
#[default]
Sample4 = 4,
}
```
# Changelog
- Modified
- `Msaa` is now enum
- Defaults to 4 samples
- Uses `.samples()` method to get the sample number as `u32`
# Migration Guide
```
let multi = Msaa { samples: 4 }
// is now
let multi = Msaa::Sample4
multi.samples
// is now
multi.samples()
```
Co-authored-by: Sjael <jakeobrien44@gmail.com>
# 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.
# Objective
- Alpha mask was previously ignored when using an unlit material.
- Fixes https://github.com/bevyengine/bevy/issues/4479
## Solution
- Extract the alpha discard to a separate function and use it when unlit is true
## Notes
I tried calling `alpha_discard()` before the `if` in pbr.wgsl, but I had errors related to having a `discard` at the beginning before doing the texture sampling. I'm not sure if there's a way to fix that instead of having the function being called in 2 places.
# Objective
Now that we can consolidate Bundles and Components under a single insert (thanks to #2975 and #6039), almost 100% of world spawns now look like `world.spawn().insert((Some, Tuple, Here))`. Spawning an entity without any components is an extremely uncommon pattern, so it makes sense to give spawn the "first class" ergonomic api. This consolidated api should be made consistent across all spawn apis (such as World and Commands).
## Solution
All `spawn` apis (`World::spawn`, `Commands:;spawn`, `ChildBuilder::spawn`, and `WorldChildBuilder::spawn`) now accept a bundle as input:
```rust
// before:
commands
.spawn()
.insert((A, B, C));
world
.spawn()
.insert((A, B, C);
// after
commands.spawn((A, B, C));
world.spawn((A, B, C));
```
All existing instances of `spawn_bundle` have been deprecated in favor of the new `spawn` api. A new `spawn_empty` has been added, replacing the old `spawn` api.
By allowing `world.spawn(some_bundle)` to replace `world.spawn().insert(some_bundle)`, this opened the door to removing the initial entity allocation in the "empty" archetype / table done in `spawn()` (and subsequent move to the actual archetype in `.insert(some_bundle)`).
This improves spawn performance by over 10%:
To take this measurement, I added a new `world_spawn` benchmark.
Unfortunately, optimizing `Commands::spawn` is slightly less trivial, as Commands expose the Entity id of spawned entities prior to actually spawning. Doing the optimization would (naively) require assurances that the `spawn(some_bundle)` command is applied before all other commands involving the entity (which would not necessarily be true, if memory serves). Optimizing `Commands::spawn` this way does feel possible, but it will require careful thought (and maybe some additional checks), which deserves its own PR. For now, it has the same performance characteristics of the current `Commands::spawn_bundle` on main.
**Note that 99% of this PR is simple renames and refactors. The only code that needs careful scrutiny is the new `World::spawn()` impl, which is relatively straightforward, but it has some new unsafe code (which re-uses battle tested BundlerSpawner code path).**
---
## Changelog
- All `spawn` apis (`World::spawn`, `Commands:;spawn`, `ChildBuilder::spawn`, and `WorldChildBuilder::spawn`) now accept a bundle as input
- All instances of `spawn_bundle` have been deprecated in favor of the new `spawn` api
- World and Commands now have `spawn_empty()`, which is equivalent to the old `spawn()` behavior.
## Migration Guide
```rust
// Old (0.8):
commands
.spawn()
.insert_bundle((A, B, C));
// New (0.9)
commands.spawn((A, B, C));
// Old (0.8):
commands.spawn_bundle((A, B, C));
// New (0.9)
commands.spawn((A, B, C));
// Old (0.8):
let entity = commands.spawn().id();
// New (0.9)
let entity = commands.spawn_empty().id();
// Old (0.8)
let entity = world.spawn().id();
// New (0.9)
let entity = world.spawn_empty();
```
