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# 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>
91 lines
3 KiB
Rust
91 lines
3 KiB
Rust
//! This example is used to test how transforms interact with alpha modes for [`Mesh2d`] entities with a [`MeshMaterial2d`].
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//! This makes sure the depth buffer is correctly being used for opaque and transparent 2d meshes
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use bevy::{
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color::palettes::css::{BLUE, GREEN, WHITE},
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prelude::*,
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sprite::AlphaMode2d,
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};
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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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.run();
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}
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fn setup(
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mut commands: Commands,
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asset_server: Res<AssetServer>,
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mut meshes: ResMut<Assets<Mesh>>,
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mut materials: ResMut<Assets<ColorMaterial>>,
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) {
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commands.spawn(Camera2dBundle::default());
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let texture_handle = asset_server.load("branding/icon.png");
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let mesh_handle = meshes.add(Rectangle::from_size(Vec2::splat(256.0)));
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// opaque
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// Each sprite should be square with the transparent parts being completely black
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// The blue sprite should be on top with the white and green one behind it
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commands.spawn((
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Mesh2d(mesh_handle.clone()),
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MeshMaterial2d(materials.add(ColorMaterial {
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color: WHITE.into(),
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alpha_mode: AlphaMode2d::Opaque,
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texture: Some(texture_handle.clone()),
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})),
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Transform::from_xyz(-400.0, 0.0, 0.0),
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));
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commands.spawn((
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Mesh2d(mesh_handle.clone()),
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MeshMaterial2d(materials.add(ColorMaterial {
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color: BLUE.into(),
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alpha_mode: AlphaMode2d::Opaque,
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texture: Some(texture_handle.clone()),
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})),
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Transform::from_xyz(-300.0, 0.0, 1.0),
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));
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commands.spawn((
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Mesh2d(mesh_handle.clone()),
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MeshMaterial2d(materials.add(ColorMaterial {
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color: GREEN.into(),
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alpha_mode: AlphaMode2d::Opaque,
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texture: Some(texture_handle.clone()),
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})),
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Transform::from_xyz(-200.0, 0.0, -1.0),
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));
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// Test the interaction between opaque/mask and transparent meshes
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// The white sprite should be:
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// - only the icon is opaque but background is transparent
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// - on top of the green sprite
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// - behind the blue sprite
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commands.spawn((
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Mesh2d(mesh_handle.clone()),
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MeshMaterial2d(materials.add(ColorMaterial {
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color: WHITE.into(),
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alpha_mode: AlphaMode2d::Mask(0.5),
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texture: Some(texture_handle.clone()),
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})),
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Transform::from_xyz(200.0, 0.0, 0.0),
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));
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commands.spawn((
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Mesh2d(mesh_handle.clone()),
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MeshMaterial2d(materials.add(ColorMaterial {
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color: BLUE.with_alpha(0.7).into(),
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alpha_mode: AlphaMode2d::Blend,
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texture: Some(texture_handle.clone()),
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})),
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Transform::from_xyz(300.0, 0.0, 1.0),
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));
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commands.spawn((
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Mesh2d(mesh_handle.clone()),
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MeshMaterial2d(materials.add(ColorMaterial {
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color: GREEN.with_alpha(0.7).into(),
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alpha_mode: AlphaMode2d::Blend,
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texture: Some(texture_handle),
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})),
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Transform::from_xyz(400.0, 0.0, -1.0),
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));
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}
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