# Objective
Continue improving the user experience of our UI Node API in the
direction specified by [Bevy's Next Generation Scene / UI
System](https://github.com/bevyengine/bevy/discussions/14437)
## Solution
As specified in the document above, merge `Style` fields into `Node`,
and move "computed Node fields" into `ComputedNode` (I chose this name
over something like `ComputedNodeLayout` because it currently contains
more than just layout info. If we want to break this up / rename these
concepts, lets do that in a separate PR). `Style` has been removed.
This accomplishes a number of goals:
## Ergonomics wins
Specifying both `Node` and `Style` is now no longer required for
non-default styles
Before:
```rust
commands.spawn((
Node::default(),
Style {
width: Val::Px(100.),
..default()
},
));
```
After:
```rust
commands.spawn(Node {
width: Val::Px(100.),
..default()
});
```
## Conceptual clarity
`Style` was never a comprehensive "style sheet". It only defined "core"
style properties that all `Nodes` shared. Any "styled property" that
couldn't fit that mold had to be in a separate component. A "real" style
system would style properties _across_ components (`Node`, `Button`,
etc). We have plans to build a true style system (see the doc linked
above).
By moving the `Style` fields to `Node`, we fully embrace `Node` as the
driving concept and remove the "style system" confusion.
## Next Steps
* Consider identifying and splitting out "style properties that aren't
core to Node". This should not happen for Bevy 0.15.
---
## Migration Guide
Move any fields set on `Style` into `Node` and replace all `Style`
component usage with `Node`.
Before:
```rust
commands.spawn((
Node::default(),
Style {
width: Val::Px(100.),
..default()
},
));
```
After:
```rust
commands.spawn(Node {
width: Val::Px(100.),
..default()
});
```
For any usage of the "computed node properties" that used to live on
`Node`, use `ComputedNode` instead:
Before:
```rust
fn system(nodes: Query<&Node>) {
for node in &nodes {
let computed_size = node.size();
}
}
```
After:
```rust
fn system(computed_nodes: Query<&ComputedNode>) {
for computed_node in &computed_nodes {
let computed_size = computed_node.size();
}
}
```
# 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>
# Objective
Adjust instruction text in some newer examples to match the [example
visual
guidelines](https://bevyengine.org/learn/contribute/helping-out/creating-examples/#visual-guidelines).
## Solution
Move text 12px from edge of screen
## Testing
```
cargo run --example alter_mesh
cargo run --example alter_sprite
cargo run --example camera_orbit
cargo run --example projection_zoom
cargo run --example irradiance_volumes
cargo run --example log_layers_ecs
cargo run --example multi_asset_sync
cargo run --example multiple_windows
cargo run --example order_independent_transparency
```
## Additional information
This isn't comprehensive, just the most trivial cases. I'll double check
my notes and probably follow up with an issue to look into visual
guidelines for a few other examples.
Fixes#15834
## Migration Guide
The APIs of `Time`, `Timer` and `Stopwatch` have been cleaned up for
consistency with each other and the standard library's `Duration` type.
The following methods have been renamed:
- `Stowatch::paused` -> `Stopwatch::is_paused`
- `Time::elapsed_seconds` -> `Time::elasped_secs` (including `_f64` and
`_wrapped` variants)
# Objective
- closes#15866
## Solution
- Simply migrate where possible.
## Testing
- Expect that CI will do most of the work. Examples is another way of
testing this, as most of the work is in that area.
---
## Notes
For now, this PR doesn't migrate `QueryState::single` and friends as for
now, this look like another issue. So for example, QueryBuilders that
used single or `World::query` that used single wasn't migrated. If there
is a easy way to migrate those, please let me know.
Most of the uses of `Query::single` were removed, the only other uses
that I found was related to tests of said methods, so will probably be
removed when we remove `Query::single`.
# Objective
- Required components replace bundles, but `SpatialBundle` is yet to be
deprecated
## Solution
- Deprecate `SpatialBundle`
- Insert `Transform` and `Visibility` instead in examples using it
- In `spawn` or `insert` inserting a default `Transform` or `Visibility`
with component already requiring either, remove those components from
the tuple
## Testing
- Did you test these changes? If so, how?
Yes, I ran the examples I changed and tests
- Are there any parts that need more testing?
The `gamepad_viewer` and and `custom_shader_instancing` examples don't
work as intended due to entirely unrelated code, didn't check main.
- How can other people (reviewers) test your changes? Is there anything
specific they need to know?
Run examples, or just check that all spawned values are identical
- If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?
Linux, wayland trough x11 (cause that's the default feature)
---
## Migration Guide
`SpatialBundle` is now deprecated, insert `Transform` and `Visibility`
instead which will automatically insert all other components that were
in the bundle. If you do not specify these values and any other
components in your `spawn`/`insert` call already requires either of
these components you can leave that one out.
before:
```rust
commands.spawn(SpatialBundle::default());
```
after:
```rust
commands.spawn((Transform::default(), Visibility::default());
```
**Ready for review. Examples migration progress: 100%.**
# Objective
- Implement https://github.com/bevyengine/bevy/discussions/15014
## Solution
This implements [cart's
proposal](https://github.com/bevyengine/bevy/discussions/15014#discussioncomment-10574459)
faithfully except for one change. I separated `TextSpan` from
`TextSpan2d` because `TextSpan` needs to require the `GhostNode`
component, which is a `bevy_ui` component only usable by UI.
Extra changes:
- Added `EntityCommands::commands_mut` that returns a mutable reference.
This is a blocker for extension methods that return something other than
`self`. Note that `sickle_ui`'s `UiBuilder::commands` returns a mutable
reference for this reason.
## Testing
- [x] Text examples all work.
---
## Showcase
TODO: showcase-worthy
## Migration Guide
TODO: very breaking
### Accessing text spans by index
Text sections are now text sections on different entities in a
hierarchy, Use the new `TextReader` and `TextWriter` system parameters
to access spans by index.
Before:
```rust
fn refresh_text(mut query: Query<&mut Text, With<TimeText>>, time: Res<Time>) {
let text = query.single_mut();
text.sections[1].value = format_time(time.elapsed());
}
```
After:
```rust
fn refresh_text(
query: Query<Entity, With<TimeText>>,
mut writer: UiTextWriter,
time: Res<Time>
) {
let entity = query.single();
*writer.text(entity, 1) = format_time(time.elapsed());
}
```
### Iterating text spans
Text spans are now entities in a hierarchy, so the new `UiTextReader`
and `UiTextWriter` system parameters provide ways to iterate that
hierarchy. The `UiTextReader::iter` method will give you a normal
iterator over spans, and `UiTextWriter::for_each` lets you visit each of
the spans.
---------
Co-authored-by: ickshonpe <david.curthoys@googlemail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# 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.
# Objective
A step in the migration to required components: scenes!
## Solution
As per the [selected
proposal](https://hackmd.io/@bevy/required_components/%2FPJtNGVMMQhyM0zIvCJSkbA):
- Deprecate `SceneBundle` and `DynamicSceneBundle`.
- Add `SceneRoot` and `DynamicSceneRoot` components, which wrap a
`Handle<Scene>` and `Handle<DynamicScene>` respectively.
## Migration Guide
Asset handles for scenes and dynamic scenes must now be wrapped in the
`SceneRoot` and `DynamicSceneRoot` components. Raw handles as components
no longer spawn scenes.
Additionally, `SceneBundle` and `DynamicSceneBundle` have been
deprecated. Instead, use the scene components directly.
Previously:
```rust
let model_scene = asset_server.load(GltfAssetLabel::Scene(0).from_asset("model.gltf"));
commands.spawn(SceneBundle {
scene: model_scene,
transform: Transform::from_xyz(-4.0, 0.0, -3.0),
..default()
});
```
Now:
```rust
let model_scene = asset_server.load(GltfAssetLabel::Scene(0).from_asset("model.gltf"));
commands.spawn((
SceneRoot(model_scene),
Transform::from_xyz(-4.0, 0.0, -3.0),
));
```
# Objective
A big step in the migration to required components: meshes and
materials!
## Solution
As per the [selected
proposal](https://hackmd.io/@bevy/required_components/%2Fj9-PnF-2QKK0on1KQ29UWQ):
- Deprecate `MaterialMesh2dBundle`, `MaterialMeshBundle`, and
`PbrBundle`.
- Add `Mesh2d` and `Mesh3d` components, which wrap a `Handle<Mesh>`.
- Add `MeshMaterial2d<M: Material2d>` and `MeshMaterial3d<M: Material>`,
which wrap a `Handle<M>`.
- Meshes *without* a mesh material should be rendered with a default
material. The existence of a material is determined by
`HasMaterial2d`/`HasMaterial3d`, which is required by
`MeshMaterial2d`/`MeshMaterial3d`. This gets around problems with the
generics.
Previously:
```rust
commands.spawn(MaterialMesh2dBundle {
mesh: meshes.add(Circle::new(100.0)).into(),
material: materials.add(Color::srgb(7.5, 0.0, 7.5)),
transform: Transform::from_translation(Vec3::new(-200., 0., 0.)),
..default()
});
```
Now:
```rust
commands.spawn((
Mesh2d(meshes.add(Circle::new(100.0))),
MeshMaterial2d(materials.add(Color::srgb(7.5, 0.0, 7.5))),
Transform::from_translation(Vec3::new(-200., 0., 0.)),
));
```
If the mesh material is missing, previously nothing was rendered. Now,
it renders a white default `ColorMaterial` in 2D and a
`StandardMaterial` in 3D (this can be overridden). Below, only every
other entity has a material:
Why white? This is still open for discussion, but I think white makes
sense for a *default* material, while *invalid* asset handles pointing
to nothing should have something like a pink material to indicate that
something is broken (I don't handle that in this PR yet). This is kind
of a mix of Godot and Unity: Godot just renders a white material for
non-existent materials, while Unity renders nothing when no materials
exist, but renders pink for invalid materials. I can also change the
default material to pink if that is preferable though.
## Testing
I ran some 2D and 3D examples to test if anything changed visually. I
have not tested all examples or features yet however. If anyone wants to
test more extensively, it would be appreciated!
## Implementation Notes
- The relationship between `bevy_render` and `bevy_pbr` is weird here.
`bevy_render` needs `Mesh3d` for its own systems, but `bevy_pbr` has all
of the material logic, and `bevy_render` doesn't depend on it. I feel
like the two crates should be refactored in some way, but I think that's
out of scope for this PR.
- I didn't migrate meshlets to required components yet. That can
probably be done in a follow-up, as this is already a huge PR.
- It is becoming increasingly clear to me that we really, *really* want
to disallow raw asset handles as components. They caused me a *ton* of
headache here already, and it took me a long time to find every place
that queried for them or inserted them directly on entities, since there
were no compiler errors for it. If we don't remove the `Component`
derive, I expect raw asset handles to be a *huge* footgun for users as
we transition to wrapper components, especially as handles as components
have been the norm so far. I personally consider this to be a blocker
for 0.15: we need to migrate to wrapper components for asset handles
everywhere, and remove the `Component` derive. Also see
https://github.com/bevyengine/bevy/issues/14124.
---
## Migration Guide
Asset handles for meshes and mesh materials must now be wrapped in the
`Mesh2d` and `MeshMaterial2d` or `Mesh3d` and `MeshMaterial3d`
components for 2D and 3D respectively. Raw handles as components no
longer render meshes.
Additionally, `MaterialMesh2dBundle`, `MaterialMeshBundle`, and
`PbrBundle` have been deprecated. Instead, use the mesh and material
components directly.
Previously:
```rust
commands.spawn(MaterialMesh2dBundle {
mesh: meshes.add(Circle::new(100.0)).into(),
material: materials.add(Color::srgb(7.5, 0.0, 7.5)),
transform: Transform::from_translation(Vec3::new(-200., 0., 0.)),
..default()
});
```
Now:
```rust
commands.spawn((
Mesh2d(meshes.add(Circle::new(100.0))),
MeshMaterial2d(materials.add(Color::srgb(7.5, 0.0, 7.5))),
Transform::from_translation(Vec3::new(-200., 0., 0.)),
));
```
If the mesh material is missing, a white default material is now used.
Previously, nothing was rendered if the material was missing.
The `WithMesh2d` and `WithMesh3d` query filter type aliases have also
been removed. Simply use `With<Mesh2d>` or `With<Mesh3d>`.
---------
Co-authored-by: Tim Blackbird <justthecooldude@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Another step in the migration to required components: lights!
Note that this does not include `EnvironmentMapLight` or reflection
probes yet, because their API hasn't been fully chosen yet.
## Solution
As per the [selected
proposals](https://hackmd.io/@bevy/required_components/%2FLLnzwz9XTxiD7i2jiUXkJg):
- Deprecate `PointLightBundle` in favor of the `PointLight` component
- Deprecate `SpotLightBundle` in favor of the `PointLight` component
- Deprecate `DirectionalLightBundle` in favor of the `DirectionalLight`
component
## Testing
I ran some examples with lights.
---
## Migration Guide
`PointLightBundle`, `SpotLightBundle`, and `DirectionalLightBundle` have
been deprecated. Use the `PointLight`, `SpotLight`, and
`DirectionalLight` components instead. Adding them will now insert the
other components required by them automatically.
# Objective
Applies feedback from previous PR #15135 'cause it got caught up in the
merge train 🚂
I couldn't resist including roll, both for completeness and due to
playing too many games that implemented it as a child.
cc: @janhohenheim
# Objective
- I've seen quite a few people on discord copy-paste the camera code of
the first-person example and then run into problems with the pitch.
- ~~Additionally, the code is framerate-dependent.~~ it's not, see
comment in PR
## Solution
- Make the code good enough to be copy-pasteable
- ~~Use `dt` to make the code framerate-independent~~ Add comment
explaining why we don't use `dt`
- Clamp the pitch
- Move the camera sensitivity into a component for better
configurability
## Testing
Didn't run the example again, but the code is straight from another
project I have open, so I'm not worried.
---------
Co-authored-by: Antony <antony.m.3012@gmail.com>
# Objective
The names of numerous rendering components in Bevy are inconsistent and
a bit confusing. Relevant names include:
- `AutoExposureSettings`
- `AutoExposureSettingsUniform`
- `BloomSettings`
- `BloomUniform` (no `Settings`)
- `BloomPrefilterSettings`
- `ChromaticAberration` (no `Settings`)
- `ContrastAdaptiveSharpeningSettings`
- `DepthOfFieldSettings`
- `DepthOfFieldUniform` (no `Settings`)
- `FogSettings`
- `SmaaSettings`, `Fxaa`, `TemporalAntiAliasSettings` (really
inconsistent??)
- `ScreenSpaceAmbientOcclusionSettings`
- `ScreenSpaceReflectionsSettings`
- `VolumetricFogSettings`
Firstly, there's a lot of inconsistency between `Foo`/`FooSettings` and
`FooUniform`/`FooSettingsUniform` and whether names are abbreviated or
not.
Secondly, the `Settings` post-fix seems unnecessary and a bit confusing
semantically, since it makes it seem like the component is mostly just
auxiliary configuration instead of the core *thing* that actually
enables the feature. This will be an even bigger problem once bundles
like `TemporalAntiAliasBundle` are deprecated in favor of required
components, as users will expect a component named `TemporalAntiAlias`
(or similar), not `TemporalAntiAliasSettings`.
## Solution
Drop the `Settings` post-fix from the component names, and change some
names to be more consistent.
- `AutoExposure`
- `AutoExposureUniform`
- `Bloom`
- `BloomUniform`
- `BloomPrefilter`
- `ChromaticAberration`
- `ContrastAdaptiveSharpening`
- `DepthOfField`
- `DepthOfFieldUniform`
- `DistanceFog`
- `Smaa`, `Fxaa`, `TemporalAntiAliasing` (note: we might want to change
to `Taa`, see "Discussion")
- `ScreenSpaceAmbientOcclusion`
- `ScreenSpaceReflections`
- `VolumetricFog`
I kept the old names as deprecated type aliases to make migration a bit
less painful for users. We should remove them after the next release.
(And let me know if I should just... not add them at all)
I also added some very basic docs for a few types where they were
missing, like on `Fxaa` and `DepthOfField`.
## Discussion
- `TemporalAntiAliasing` is still inconsistent with `Smaa` and `Fxaa`.
Consensus [on
Discord](https://discord.com/channels/691052431525675048/743663924229963868/1280601167209955431)
seemed to be that renaming to `Taa` would probably be fine, but I think
it's a bit more controversial, and it would've required renaming a lot
of related types like `TemporalAntiAliasNode`,
`TemporalAntiAliasBundle`, and `TemporalAntiAliasPlugin`, so I think
it's better to leave to a follow-up.
- I think `Fog` should probably have a more specific name like
`DistanceFog` considering it seems to be distinct from `VolumetricFog`.
~~This should probably be done in a follow-up though, so I just removed
the `Settings` post-fix for now.~~ (done)
---
## Migration Guide
Many rendering components have been renamed for improved consistency and
clarity.
- `AutoExposureSettings` → `AutoExposure`
- `BloomSettings` → `Bloom`
- `BloomPrefilterSettings` → `BloomPrefilter`
- `ContrastAdaptiveSharpeningSettings` → `ContrastAdaptiveSharpening`
- `DepthOfFieldSettings` → `DepthOfField`
- `FogSettings` → `DistanceFog`
- `SmaaSettings` → `Smaa`
- `TemporalAntiAliasSettings` → `TemporalAntiAliasing`
- `ScreenSpaceAmbientOcclusionSettings` → `ScreenSpaceAmbientOcclusion`
- `ScreenSpaceReflectionsSettings` → `ScreenSpaceReflections`
- `VolumetricFogSettings` → `VolumetricFog`
---------
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# 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
# Objective
Use the new `AccumulatedMouseMotion` and `AccumulatedMouseScroll`
resources in place of mouse event handling.
I left the `mouse_input_events` example alone, since by its nature it
demonstrates event detection.
Fixes#14066
## Testing
Ran each example locally before and after changes.
_copy-pasted from my doc comment in the code_
# Objective
This example shows how to properly handle player input, advance a
physics simulation in a fixed timestep, and display the results.
The classic source for how and why this is done is Glenn Fiedler's
article [Fix Your
Timestep!](https://gafferongames.com/post/fix_your_timestep/).
## Motivation
The naive way of moving a player is to just update their position like
so:
```rust
transform.translation += velocity;
```
The issue here is that the player's movement speed will be tied to the
frame rate.
Faster machines will move the player faster, and slower machines will
move the player slower.
In fact, you can observe this today when running some old games that did
it this way on modern hardware!
The player will move at a breakneck pace.
The more sophisticated way is to update the player's position based on
the time that has passed:
```rust
transform.translation += velocity * time.delta_seconds();
```
This way, velocity represents a speed in units per second, and the
player will move at the same speed regardless of the frame rate.
However, this can still be problematic if the frame rate is very low or
very high. If the frame rate is very low, the player will move in large
jumps. This may lead to a player moving in such large jumps that they
pass through walls or other obstacles. In general, you cannot expect a
physics simulation to behave nicely with *any* delta time. Ideally, we
want to have some stability in what kinds of delta times we feed into
our physics simulation.
The solution is using a fixed timestep. This means that we advance the
physics simulation by a fixed amount at a time. If the real time that
passed between two frames is less than the fixed timestep, we simply
don't advance the physics simulation at all.
If it is more, we advance the physics simulation multiple times until we
catch up. You can read more about how Bevy implements this in the
documentation for
[`bevy::time::Fixed`](https://docs.rs/bevy/latest/bevy/time/struct.Fixed.html).
This leaves us with a last problem, however. If our physics simulation
may advance zero or multiple times per frame, there may be frames in
which the player's position did not need to be updated at all, and some
where it is updated by a large amount that resulted from running the
physics simulation multiple times. This is physically correct, but
visually jarring. Imagine a player moving in a straight line, but
depending on the frame rate, they may sometimes advance by a large
amount and sometimes not at all. Visually, we want the player to move
smoothly. This is why we need to separate the player's position in the
physics simulation from the player's position in the visual
representation. The visual representation can then be interpolated
smoothly based on the last and current actual player position in the
physics simulation.
This is a tradeoff: every visual frame is now slightly lagging behind
the actual physical frame, but in return, the player's movement will
appear smooth. There are other ways to compute the visual representation
of the player, such as extrapolation. See the [documentation of the
lightyear
crate](https://cbournhonesque.github.io/lightyear/book/concepts/advanced_replication/visual_interpolation.html)
for a nice overview of the different methods and their tradeoffs.
## Implementation
- The player's velocity is stored in a `Velocity` component. This is the
speed in units per second.
- The player's current position in the physics simulation is stored in a
`PhysicalTranslation` component.
- The player's previous position in the physics simulation is stored in
a `PreviousPhysicalTranslation` component.
- The player's visual representation is stored in Bevy's regular
`Transform` component.
- Every frame, we go through the following steps:
- Advance the physics simulation by one fixed timestep in the
`advance_physics` system.
This is run in the `FixedUpdate` schedule, which runs before the
`Update` schedule.
- Update the player's visual representation in the
`update_displayed_transform` system.
This interpolates between the player's previous and current position in
the physics simulation.
- Update the player's velocity based on the player's input in the
`handle_input` system.
## Relevant Issues
Related to #1259.
I'm also fairly sure I've seen an issue somewhere made by
@alice-i-cecile about showing how to move a character correctly in a
fixed timestep, but I cannot find it.
# Objective
[`StableInterpolate`](https://dev-docs.bevyengine.org/bevy/math/trait.StableInterpolate.html)
was introduced after this example was written (or more accurately, the
two PRs were merged on the same day and developed in parallel).
The example used `Vec3::lerp` where I believe it is now preferred to use
`smooth_nudge`.
## Solution
Its not entirely clear to me whether `StableInterpolate` should be
preferred in this scenario, although it seems likely. So I figured a PR
to make the change would either result in it being merged or denied with
a reason.
## Testing
```
cargo run --example 2d_top_down_camera
```
Co-authored-by: François Mockers <mockersf@gmail.com>
# Objective
A very common way to organize a first-person view is to split it into
two kinds of models:
- The *view model* is the model that represents the player's body.
- The *world model* is everything else.
The reason for this distinction is that these two models should be
rendered with different FOVs.
The view model is typically designed and animated with a very specific
FOV in mind, so it is
generally *fixed* and cannot be changed by a player. The world model, on
the other hand, should
be able to change its FOV to accommodate the player's preferences for
the following reasons:
- *Accessibility*: How prone is the player to motion sickness? A wider
FOV can help.
- *Tactical preference*: Does the player want to see more of the
battlefield?
Or have a more zoomed-in view for precision aiming?
- *Physical considerations*: How well does the in-game FOV match the
player's real-world FOV?
Are they sitting in front of a monitor or playing on a TV in the living
room? How big is the screen?
## Solution
I've added an example implementing the described setup as follows.
The `Player` is an entity holding two cameras, one for each model. The
view model camera has a fixed
FOV of 70 degrees, while the world model camera has a variable FOV that
can be changed by the player.
I use different `RenderLayers` to select what to render.
- The world model camera has no explicit `RenderLayers` component, so it
uses the layer 0.
All static objects in the scene are also on layer 0 for the same reason.
- The view model camera has a `RenderLayers` component with layer 1, so
it only renders objects
explicitly assigned to layer 1. The arm of the player is one such
object.
The order of the view model camera is additionally bumped to 1 to ensure
it renders on top of the world model.
- The light source in the scene must illuminate both the view model and
the world model, so it is
assigned to both layers 0 and 1.
To better see the effect, the player can move the camera by dragging
their mouse and change the world model's FOV with the arrow keys. The
arrow up key maps to "decrease FOV" and the arrow down key maps to
"increase FOV". This sounds backwards on paper, but is more intuitive
when actually changing the FOV in-game since a decrease in FOV looks
like a zoom-in.
I intentionally do not allow changing the view model's FOV even though
it would be illustrative because that would be an anti-pattern and bloat
the code a bit.
The example is called `first_person_view_model` and not just
`first_person` because I want to highlight that this is not a simple
flycam, but actually renders the player.
## Testing
Default FOV:
<img width="1392" alt="image"
src="https://github.com/bevyengine/bevy/assets/9047632/8c2e804f-fac2-48c7-8a22-d85af999dfb2">
Decreased FOV:
<img width="1392" alt="image"
src="https://github.com/bevyengine/bevy/assets/9047632/1733b3e5-f583-4214-a454-3554e3cbd066">
Increased FOV:
<img width="1392" alt="image"
src="https://github.com/bevyengine/bevy/assets/9047632/0b0640e6-5743-46f6-a79a-7181ba9678e8">
Note that the white bar on the right represents the player's arm, which
is more obvious in-game because you can move the camera around.
The box on top is there to make sure that the view model is receiving
shadows.
I tested only on macOS.
---
## Changelog
I don't think new examples go in here, do they?
## Caveat
The solution used here was implemented with help by @robtfm on
[Discord](https://discord.com/channels/691052431525675048/866787577687310356/1241019224491561000):
> shadow maps are specific to lights, not to layers
> if you want shadows from some meshes that are not visible, you could
have light on layer 1+2, meshes on layer 2, camera on layer 1 (for
example)
> but this might change in future, it's not exactly an intended feature
In other words, the example code as-is is not guaranteed to work in the
future. I want to bring this up because the use-case presented here is
extremely common in first-person games and important for accessibility.
It would be good to have a blessed and easy way of how to achieve it.
I'm also not happy about how I get the `perspective` variable in
`change_fov`. Very open to suggestions :)
## Related issues
- Addresses parts of #12658
- Addresses parts of #12588
---------
Co-authored-by: Pascal Hertleif <killercup@gmail.com>
# Objective
This PR addresses the 2D part of #12658. I plan to separate the examples
and make one PR per camera example.
## Solution
Added a new top-down example composed of:
- [x] Player keyboard movements
- [x] UI for keyboard instructions
- [x] Colors and bloom effect to see the movement of the player
- [x] Camera smooth movement towards the player (lerp)
## Testing
```bash
cargo run --features="wayland,bevy/dynamic_linking" --example 2d_top_down_camera
```
https://github.com/bevyengine/bevy/assets/10638479/95db0587-e5e0-4f55-be11-97444b795793
