namespace Mf {
-class Plane
+class Aabb;
+class Sphere;
+
+
+/*
+ * A plane in 3-space defined by the equation Ax + By + Cz = D, where [A, B, C]
+ * is normal to the plane.
+ */
+
+struct Plane
{
- Vector4 components;
+ Vector3 normal;
+ Scalar d;
+
+ typedef enum
+ {
+ NEGATIVE = -1,
+ INTERSECT = 0,
+ POSITIVE = 1
+ } Halfspace;
+
+ Plane() {}
+ Plane(const Vector3& vector, Scalar scalar) :
+ normal(vector),
+ d(scalar) {}
+ Plane(Scalar a, Scalar b, Scalar c, Scalar scalar) :
+ normal(a, b, c),
+ d(scalar) {}
+
+
+ /* Causes the normal of the plane to become normalized. The scalar may also
+ * be changed to keep the equation true. */
+ void normalize()
+ {
+ Scalar mag = normal.length();
+
+ normal /= mag;
+ d /= mag;
+ }
+
+ /**
+ * Determine the shortest distance between a point and the plane. */
+
+ Scalar getDistanceToPoint(const Vector3& point) const
+ {
+ return cml::dot(point, normal) + d;
+ }
+
+ Halfspace intersects(const Vector3& point) const
+ {
+ Scalar distance = getDistanceToPoint(point);
+
+ if (isEqual(distance, 0.0)) return INTERSECT;
+ else if (distance < 0.0) return NEGATIVE;
+ else return POSITIVE;
+ }
-public:
+ Halfspace intersects(const Aabb& aabb) const;
+ Halfspace intersects(const Sphere& sphere) const;
};