bevy/examples/3d/spherical_area_lights.rs
Joona Aalto 54006b107b
Migrate meshes and materials to required components (#15524)
# 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:

![Näyttökuva 2024-09-29
181746](https://github.com/user-attachments/assets/5c8be029-d2fe-4b8c-ae89-17a72ff82c9a)

![Näyttökuva 2024-09-29
181918](https://github.com/user-attachments/assets/58adbc55-5a1e-4c7d-a2c7-ed456227b909)

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>
2024-10-01 21:33:17 +00:00

66 lines
1.9 KiB
Rust

//! Demonstrates how lighting is affected by different radius of point lights.
use bevy::prelude::*;
fn main() {
App::new()
.insert_resource(AmbientLight {
brightness: 60.0,
..default()
})
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.run();
}
fn setup(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
) {
// camera
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(0.2, 1.5, 2.5).looking_at(Vec3::ZERO, Vec3::Y),
..default()
});
// plane
commands.spawn((
Mesh3d(meshes.add(Plane3d::default().mesh().size(100.0, 100.0))),
MeshMaterial3d(materials.add(StandardMaterial {
base_color: Color::srgb(0.2, 0.2, 0.2),
perceptual_roughness: 0.08,
..default()
})),
));
const COUNT: usize = 6;
let position_range = -2.0..2.0;
let radius_range = 0.0..0.4;
let pos_len = position_range.end - position_range.start;
let radius_len = radius_range.end - radius_range.start;
let mesh = meshes.add(Sphere::new(1.0).mesh().uv(120, 64));
for i in 0..COUNT {
let percent = i as f32 / COUNT as f32;
let radius = radius_range.start + percent * radius_len;
// sphere light
commands
.spawn((
Mesh3d(mesh.clone()),
MeshMaterial3d(materials.add(StandardMaterial {
base_color: Color::srgb(0.5, 0.5, 1.0),
unlit: true,
..default()
})),
Transform::from_xyz(position_range.start + percent * pos_len, 0.3, 0.0)
.with_scale(Vec3::splat(radius)),
))
.with_child(PointLight {
radius,
color: Color::srgb(0.2, 0.2, 1.0),
..default()
});
}
}