Sphere

A sphere is the 3D version of a circle. It is defined by a 3D point in space and a radius. Like a circle in 2D, in 3D the sphere is considered to be one of the simplest shapes we can implement. The simplicity of a sphere makes it very fast for collision detection:

Getting ready

We are going to declare a new Sphere structure in the Geometry3D.h header file. This structure will hold a position and a radius.

How to do it…

Follow these steps to implement a 3D sphere:

1. Declare the Sphere structure in Geometry3D.h:

   typedef struct Sphere {

2. Start by declaring the position and radius variables of the Sphere structure:

      Point position;
      float radius;

3. Finish implementing the structure by adding a default constructor, and one which takes a point and radius to construct a sphere out of:

      inline Sphere() : radius(1.0f) { }
      inline Sphere(const Point& p, float r) :
          position(p), radius(r) { }
   } Sphere;

How it works…

The Sphere structure contains a position and a radius. It has two constructors...