BoundingBox

Axis-aligned bounding box (AABB) for entity collision detection.

Access

BoundingBox boundingBoxComponent = store.getComponent(ref, BoundingBox.getComponentType());
Box box = boundingBoxComponent.getBoundingBox();

Box Dimensions

Box box = boundingBoxComponent.getBoundingBox();

// dimensions
double width = box.width();    // max.x - min.x
double height = box.height();  // max.y - min.y
double depth = box.depth();    // max.z - min.z
double volume = box.getVolume();

// corners
Vector3d min = box.getMin();  // minimum corner
Vector3d max = box.getMax();  // maximum corner

Creating Bounding Boxes

// horizontally centered at origin, bottom at y=0 (typical for entities)
Box entityBox = Box.horizontallyCentered(0.6, 1.8, 0.6);
// creates: min=(-0.3, 0, -0.3), max=(0.3, 1.8, 0.3)

// explicit min/max corners
Box customBox = new Box(-0.5, 0.0, -0.5, 0.5, 2.0, 0.5);

// set on entity
store.putComponent(ref, BoundingBox.getComponentType(), new BoundingBox(entityBox));

Detail Boxes

For complex collision shapes, entities can have named sub-hitboxes:

Map<String, DetailBox[]> detailBoxes = boundingBoxComponent.getDetailBoxes();

// detail boxes are typically set from ModelComponent
boundingBoxComponent.setDetailBoxes(model.getDetailBoxes());

Detail boxes are used for precise hit detection (e.g., headshots) rather than general collision.

Automatic Updates

When an entity has a ModelComponent, its bounding box is automatically updated:

• ModelSystems.ModelSpawned - sets initial bounding box from model
• ModelSystems.UpdateBoundingBox - updates when model changes
• UpdateCrouchingBoundingBox - adjusts for crouch state

Collision System

Entities with BoundingBox + TransformComponent (and without Intangible) are tracked in spatial queries for collision detection.

Finding Collisions

CollisionResult result = new CollisionResult();

// find what a moving box would hit (static method)
boolean hit = CollisionModule.findCollisions(
    boundingBox,        // the collider shape
    position,           // starting position
    velocity,           // movement direction
    result,             // stores collision data
    componentAccessor
);

if (hit) {
    BlockCollisionData collision = result.getFirstBlockCollision();
    if (collision != null) {
        Vector3d hitPoint = collision.collisionPoint;
        Vector3d normal = collision.collisionNormal;
    }
}

Entity-to-Entity Collision

// check if two entities overlap
BoundingBox boxA = store.getComponent(refA, BoundingBox.getComponentType());
BoundingBox boxB = store.getComponent(refB, BoundingBox.getComponentType());
TransformComponent transformA = store.getComponent(refA, TransformComponent.getComponentType());
TransformComponent transformB = store.getComponent(refB, TransformComponent.getComponentType());

// manual AABB intersection check
Box worldBoxA = boxA.getBoundingBox().clone().translate(transformA.getPosition());
Box worldBoxB = boxB.getBoundingBox().clone().translate(transformB.getPosition());
boolean overlaps = worldBoxA.isIntersecting(worldBoxB);

Excluding from Collision

Add the Intangible component to exclude an entity from collision queries:

store.ensureComponent(ref, Intangible.getComponentType());

See Intangible for details.

Related Components

Component	Relationship
TransformComponent	Provides position for world-space collision
ModelComponent	Source of bounding box dimensions
Intangible	Excludes from collision spatial queries
Invulnerable	Separate from collision (affects damage only)