# Rantz Spatial2D
A 2d transform system for the [Bevy](https://bevyengine.org/) game engine that supports Transform propagation controls.
## Core Types
### `Position2D`
The `Position2D` struct represents a 2D point in space. It has two fields: `x` and `y`, representing the Cartesian coordinates of the point.
### `Rotation2D`
The `Rotation2D` struct represents a 2D rotation. It can be used with either radians or degrees.
### `Scale2D`
The `Scale2D` struct represents a 2D scale. It has two fields: `x` and `y`, representing the scale factors for the x and y axes respectively.
### `SpatialBundle2D`
The `SpatialBundle2D` struct represents the spatial state of a transform in 2D. It contains a `Position2D`, `Rotation2D`, and `Scale2D`. It provides a convenient way to store and manipulate the spatial state of your game objects.
When you add a `SpatialBundle2D` to an entity, it will also automatically add a `SpatialBundle`, making it easy to use the spatial 2D system with Bevy's built-in transform system.
### `DrawOrder`
The `DrawOrder` struct is used to specify the draw layering of entities in your game. It is a wrapper over an f32, with higher values drawing above lower values.
## propagation Types
The following enums are used to control how the spatial components of an entity are propagated to its children.
### `PositionPropagation`
The `PositionPropagation` enum has two variants:
**Relative:** **[Default]**The position of a child entity is relative to its parent's position.
**Absolute:** The position of a child entity is absolute and does not take into account its parent's position.
### `RotationPropagation`
The `RotationPropagation` enum has two variants:
**Relative:** **[Default]**The rotation of a child entity is relative to its parent's rotation.
**Absolute:** The rotation of a child entity is absolute and does not take into account its parent's rotation.
By default, both Positionpropagation and Rotationpropagation are set to Relative.
### `ScalePropagation`
The `ScalePropagation` enum has two variants:
**Relative:** **[Default]**The rotation of a child entity is relative to its parent's rotation.
**Absolute:** The rotation of a child entity is absolute and does not take into account its parent's rotation.
### Compasses
In addition to the above, and not included in the SpatialBundle2D are `Compass`, `CompassRose`, and `CompassHalfwinds`. It is very common in 2D games to need to know the compass direction a given entity is facing in order to choose which sprite to draw. These enums can be included as a component on anything with a Rotation2D, and as part of transform propagation, there values will be updated to match the objects rotation.
## Feature Flags
* `bevy` - Adds systems to update Bevys internal transform based on the contents of `SpatialBundle2D`, and a plugin to manage said systems, register types, etc.
* `serde` - Adds impls for serde:Serialize and serde:Deserialize
**Default:** `bevy`
## Usage
Add the crate to your `Cargo.toml`
If using bevy, add `SpatialPlugin2D` to your app.