adds documentation for AABB and revised IShape2D

main
Evan Hemsley 2019-12-31 14:37:49 -08:00
parent f8354b9970
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2 changed files with 35 additions and 7 deletions

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---
title: "AABB"
date: 2019-12-31T14:36:00-07:00
weight: 6
---
*AABB*, or axis-aligned bounding box, is defined by a minimum point and a maximum point. It is used for broad-phase collision detection. It represents a rectangular outline of the shape so we can quickly insert shapes into a *SpatialHash*.
## Properties
##### **public Vector2 Min { get; private set; }**
The minimum point of the AABB.
##### **public Vector2 Max { get; private set; }**
The maximum point of the AABB.
## Methods
##### **public static AABB FromVertices(IEnumerable<Position2D> vertices)**
Can be used to generate an AABB from an arbitrary collection of vertices. It is generally better to define a more efficient AABB generation method based on the properties of a particular shape, but this can be used for an arbitrary collection of vertices, like a polygon.
##### **public static AABB Transformed(AABB aabb, Transform2D transform)**
Efficiently transforms an AABB. Used internally by SpatialHash to quickly transform a shape's AABB.

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@ -8,6 +8,12 @@ An *IShape2D* is an interface that, when implemented, allows for spatial hashing
Your *IShape2D* implementations should be structs for memory efficiency purposes. Your *IShape2D* implementations should be structs for memory efficiency purposes.
## Properties
##### **public AABB { get; }**
An axis-aligned bounding box for the shape. This is stored so we can efficiently transform the AABB when necessary.
## Methods ## Methods
##### **Vector2 Support(Vector2 direction, Transform2D transform)** ##### **Vector2 Support(Vector2 direction, Transform2D transform)**
@ -34,13 +40,8 @@ A method which returns the axis-aligned bounding box for the transformed shape.
For example, the AABB method for Bonk's *Circle* implementation: For example, the AABB method for Bonk's *Circle* implementation:
```cs ```cs
public AABB AABB(Transform2D Transform2D) public AABB TransformedAABB(Transform2D Transform2D)
{ {
return new AABB( return AABB.Transformed(AABB, transform2D);
Transform2D.Position.X - Radius,
Transform2D.Position.Y - Radius,
Transform2D.Position.X + Radius,
Transform2D.Position.Y + Radius
);
} }
``` ```