source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/Plane3.h @ 2944

#ifndef __Plane3_H__
#define __Plane3_H__

#include "Vector3.h"


namespace CHCDemoEngine 
{

/** Class describing a plane in 3D space.
*/
class Plane3 
{
public:

        Plane3() {}

        Plane3(const Vector3 &a, const Vector3 &b, const Vector3 &c);
        /** Note: we assume that the normal vector is already normalized.
        */
        Plane3(const Vector3 &normal, const Vector3 &point);

        inline void ReverseOrientation()
        {
                mNormal *= -1;
                mD *= -1;
        }
        /** Get distance to a point.
        */
        inline float Distance(const Vector3 &v) const 
        {
                return DotProd(v, mNormal) + mD;
        }

        enum {BACK_SIDE = -1, INTERSECTS = 0, FRONT_SIDE = 1};
        /** Returns 1 if v is on front side, -1 if on back side, 0 if on plane.
        */
        int Side(const Vector3 &v, float threshold = 1e-6) const;
        /** Finds intersection of line segment between points a and b with plane.
            @param a start point
                @param b end point
                @param t if not NULL, returns parameter value of intersections
                @param coplanar if not NULL, returns true if plane and line segments are coplanar.
        */
        Vector3 FindIntersection(const Vector3 &a,
                                     const Vector3 &b,
                                                         float *t = NULL,
                                                         bool *coplanar = NULL) const;

        /** Finds value of intersection parameter t on line segment from a to b.
            @returns 0 if coplanar, else parameter t
        */
        float FindT(const Vector3 &a, const Vector3 &b) const;

        operator const float*() const 
        { 
                return (const float*) this; 
        }

        float& operator[] (const int inx) 
        {
                return (&mNormal.x)[inx];
        }

        const float &operator[] (const int inx) const 
        {
                return *(&mNormal.x + inx);
        }
        /** Transforms the plane  with the matrix m.
        */
        void Transform(const Matrix4x4 &m);


        ///////////
        //-- friends

        friend bool     PlaneIntersection(const Plane3 &a, const Plane3 &b, const Plane3 &c, Vector3 &result);

        friend bool PlaneIntersection(const Plane3 &p1, const Plane3 &p2);
        

        friend std::ostream &operator<<(std::ostream &s, const Plane3 &p) 
        {       
                s << p.mNormal << " " << p.mD;
                return s;
        }


//protected:

        ///////////////

        Vector3 mNormal;
        float mD;
};


}
#endif