11 releases
0.5.0 | Feb 20, 2024 |
---|---|
0.4.1 | Dec 6, 2022 |
0.4.0 | Nov 24, 2022 |
0.3.1 | Oct 22, 2022 |
0.1.2 | Jun 30, 2022 |
#397 in Game dev
105 downloads per month
41KB
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bevy_sepax2d
Plugins and helpful methods for using sepax2d with Bevy for 2d overlap detection and collision resolution.
Compatible Versions
bevy | bevy_sepax2d |
---|---|
0.12 | 0.5 |
0.9 | 0.4 |
0.8 | 0.2, 0.3 |
0.7 | 0.1 |
Usage
Add the following to the [dependencies]
section of your Cargo.toml
:
sepax2d = "0.3"
bevy_sepax2d = "0.5"
There is an additional debug
feature which can be used to render collision shapes to the screen.
This relies on Bevy's default features as well as bevy_prototype_lyon
for rendering. This can be enabled in your Cargo.toml:
bevy_sepax2d = { version = "0.5", features = ["debug"] }
Documentation for version 0.4 and older: check the examples for code working with 0.5 (Bevy 0.12)
To add a shape to your world, simply insert a Sepax
struct into any entity.
let polygon = Polygon::from_vertices((0.0, 0.0), vec![(0.0, -25.0), (15.0, 15.0), (-15.0, 15.0)]);
let convex = Convex::Polygon(polygon);
commands.spawn(Sepax { convex });
Sepax
has one field, convex
: This is an instance of the Convex
enum, which has possible values
for each shape supported by sepax2d: Polygon
, Circle
, AABB
, Parallelogram
, and Capsule
. Each variant contains
an instance of the corresponding shape. Check the sepax2d
documentation for information about each one.
The underlying shape can be conveniently accessed through the shape
and shape_mut
methods, which provide
easy access to references to the underlying shapes without need to match the enum.
fn bullet_system
(
mut bullets: Query<(&Bullet, &Sepax)>,
targets: Query<&Sepax, Without<Bullet>>
)
{
for (_b, bullet) in bullets.iter()
{
for target in targets.iter()
{
if sat_overlap(wall.shape(), bullet.shape())
{
//Bullet hit target, now react appropriately
}
}
}
}
If included, the SepaxPlugin
provides the following basic features, which occur during Bevy's
PostUpdate
stage:
- Resets the collision information from the previous frame
- Updates the location of any
Sepax
component attached to aTransform
- Provides inelastic collision between entities with a
Sepax
shape which are taggedMovable
and those that are not movable.
These systems are public, so you may include them manually if you do not want all of them. This is likely to happen when you want to introduce finer control over which objects collide with which, but still want to reset collision data and update locations. Or, you may want to collide and update locations, but want to maintain old collision data until it has been processed.
The Movable
component signifies that an entity is dynamic. By contrast, the absence of a Movable
component denotes a static object which is treated like a "wall" that movable entities should collide
with. Use the NoCollision
marker component on either a Movable
or non-Movable
entity to exclude
it from the collision process.
The Movable
struct contains a list of normalized collision resolution vectors from the previous frame during the
Update
stage for you to react to in your code. These vectors represent the direction AWAY from the
object that was collided with. For example, the following code zeroes out the y-component
of an entity's velocity when it lands on or hits the bottom of a platform:
fn velocity_correction_system(mut query: Query<(&mut Velocity, &Movable)>)
{
for (mut velocity, correction) in query.iter_mut()
{
for (_x, y) in correction.axes.iter()
{
if y.abs() > f32::EPSILON && velocity.y.is_sign_positive() != y.is_sign_positive()
{
velocity.y = 0.0;
}
}
}
}
Debug Rendering
If you enable the debug
feature, then you can render your shapes with the help of bevy_prototype_lyon.
The following convenience methods help with rendering:
Sepax::as_shape_bundle
will take in a reference to aSepax
struct and aDrawMode
and return aShapeBundle
to be added to an entity.Sepax::shape_geometry
will take in a reference to aSepax
struct and return aPath
representing the given shape. Use this in conjunction withShapePath
to change the rendered shape at runtime. Check out the platformer example to see this in action!
let circle = Circle::new((0.0, 0.0), 15.0);
let convex = Convex::Circle(circle);
let player = DrawMode::Fill(FillMode::color(Color::WHITE));
commands.spawn(Sepax::as_shape_bundle(&convex, player))
.insert(Sepax { convex })
.insert(Movable { axes: Vec::new() });
Features
debug
- Enables rendering of shapes.
serde
- Enables (De)Serialization of Convex and Sepax types for easy loading.
Examples
The repository includes two example applications showcasing a basic platformer (which only uses the basic plugin), and a shmup which demonstrates some custom systems.
cargo run --features="debug" --example platformer
cargo run --features="debug" --example shmup
Contribution
Please feel free to suggest additional features, bug fixes, or optimizations. Thanks!
Dependencies
~19–55MB
~1M SLoC