bevy/examples/2d/mesh2d_alpha_mode.rs
IceSentry 5abc32ceda
Add 2d opaque phase with depth buffer (#13069)
This PR is based on top of #12982

# Objective

- Mesh2d currently only has an alpha blended phase. Most sprites don't
need transparency though.
- For some 2d games it can be useful to have a 2d depth buffer

## Solution

- Add an opaque phase to render Mesh2d that don't need transparency
- This phase currently uses the `SortedRenderPhase` to make it easier to
implement based on the already existing transparent phase. A follow up
PR will switch this to `BinnedRenderPhase`.
- Add a 2d depth buffer
- Use that depth buffer in the transparent phase to make sure that
sprites and transparent mesh2d are displayed correctly

## Testing

I added the mesh2d_transforms example that layers many opaque and
transparent mesh2d to make sure they all get displayed correctly. I also
confirmed it works with sprites by modifying that example locally.

---

## Changelog

- Added `AlphaMode2d`
- Added `Opaque2d` render phase
- Camera2d now have a `ViewDepthTexture` component

## Migration Guide

- `ColorMaterial` now contains `AlphaMode2d`. To keep previous
behaviour, use `AlphaMode::BLEND`. If you know your sprite is opaque,
use `AlphaMode::OPAQUE`

## Follow up PRs

- See tracking issue: #13265

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Christopher Biscardi <chris@christopherbiscardi.com>
2024-08-07 00:22:09 +00:00

97 lines
3.3 KiB
Rust

//! This example is used to test how transforms interact with alpha modes for [`MaterialMesh2dBundle`] entities.
//! This makes sure the depth buffer is correctly being used for opaque and transparent 2d meshes
use bevy::{
color::palettes::css::{BLUE, GREEN, WHITE},
prelude::*,
sprite::{AlphaMode2d, MaterialMesh2dBundle},
};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.run();
}
fn setup(
mut commands: Commands,
asset_server: Res<AssetServer>,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<ColorMaterial>>,
) {
commands.spawn(Camera2dBundle::default());
let texture_handle = asset_server.load("branding/icon.png");
let mesh_handle = meshes.add(Rectangle::from_size(Vec2::splat(256.0)));
// opaque
// Each sprite should be square with the transparent parts being completely black
// The blue sprite should be on top with the white and green one behind it
commands.spawn(MaterialMesh2dBundle {
mesh: mesh_handle.clone().into(),
material: materials.add(ColorMaterial {
color: WHITE.into(),
alpha_mode: AlphaMode2d::Opaque,
texture: Some(texture_handle.clone()),
}),
transform: Transform::from_xyz(-400.0, 0.0, 0.0),
..default()
});
commands.spawn(MaterialMesh2dBundle {
mesh: mesh_handle.clone().into(),
material: materials.add(ColorMaterial {
color: BLUE.into(),
alpha_mode: AlphaMode2d::Opaque,
texture: Some(texture_handle.clone()),
}),
transform: Transform::from_xyz(-300.0, 0.0, 1.0),
..default()
});
commands.spawn(MaterialMesh2dBundle {
mesh: mesh_handle.clone().into(),
material: materials.add(ColorMaterial {
color: GREEN.into(),
alpha_mode: AlphaMode2d::Opaque,
texture: Some(texture_handle.clone()),
}),
transform: Transform::from_xyz(-200.0, 0.0, -1.0),
..default()
});
// Test the interaction between opaque and transparent meshes
// The white sprite should be:
// - fully opaque
// - on top of the green sprite
// - behind the blue sprite
commands.spawn(MaterialMesh2dBundle {
mesh: mesh_handle.clone().into(),
material: materials.add(ColorMaterial {
color: WHITE.into(),
alpha_mode: AlphaMode2d::Opaque,
texture: Some(texture_handle.clone()),
}),
transform: Transform::from_xyz(200.0, 0.0, 0.0),
..default()
});
commands.spawn(MaterialMesh2dBundle {
mesh: mesh_handle.clone().into(),
material: materials.add(ColorMaterial {
color: BLUE.with_alpha(0.7).into(),
alpha_mode: AlphaMode2d::Blend,
texture: Some(texture_handle.clone()),
}),
transform: Transform::from_xyz(300.0, 0.0, 1.0),
..default()
});
commands.spawn(MaterialMesh2dBundle {
mesh: mesh_handle.clone().into(),
material: materials.add(ColorMaterial {
color: GREEN.with_alpha(0.7).into(),
alpha_mode: AlphaMode2d::Blend,
texture: Some(texture_handle),
}),
transform: Transform::from_xyz(400.0, 0.0, -1.0),
..default()
});
}