Sphere

Represents a bounding sphere in 3D space.

Sphere stores a center point and a radius and is used as a simple bounding volume for intersection tests, culling, and spatial queries. A negative radius indicates an empty sphere. The class supports expansion with points, merging with other spheres, translation, and transformation by a matrix.

Construction

Constructors

Sphere() constexpr

Constructs a sphere from a center and radius.

Sphere::Sphere(const Vector3 center, float radius);

Parameter	Description
center	Sphere center.
radius	Sphere radius (negative indicates empty).

Properties

center Vector3

Sphere center in space.

Vector3 center {Vector3::Zero()};

radius float

Sphere radius. A negative value indicates an empty sphere.

float radius {-1.0f};

Functions

ApplyTransform() void

Applies a 4×4 transform to the sphere.

The center is transformed directly, while the radius is scaled by the largest scale factor present in the matrix to ensure conservative bounding behavior.

void Sphere::ApplyTransform(const Matrix4& transform);

Parameter	Description
transform	Matrix to apply.

ExpandWithPoint() void

Expands the sphere to include a point.

If the sphere is empty, it becomes a zero-radius sphere at the point. Otherwise, the sphere grows minimally to contain the point.

void Sphere::ExpandWithPoint(const Vector3& p);

Parameter	Description
p	Point to include.

IsEmpty() bool

Checks whether the sphere is empty.

bool Sphere::IsEmpty() const;

Radius() float

Returns the sphere radius.

float Sphere::Radius() const;

Reset() void

Resets the sphere to an empty state.

void Sphere::Reset();

Translate() void

Translates the sphere by a vector.

void Sphere::Translate(const Vector3& translation);

Parameter	Description
translation	Offset to apply.

Union() void

Expands this sphere to fully contain another sphere.

Handles empty spheres, identical centers, and general cases using two directional expansion points.

void Sphere::Union(const Sphere& other);

Parameter	Description
other	Sphere to merge.