source: GTP/trunk/Lib/Vis/Preprocessing/src/Plane3.h @ 1418

#ifndef _Plane3_H__
#define _Plane3_H__

#include "Vector3.h"

namespace GtpVisibilityPreprocessor {

  
/** 3D Plane */
class Plane3 {
public:

  Vector3 mNormal;
  float mD;
  
  Plane3() {}
  
  Plane3(const Vector3 &a,
                 const Vector3 &b,
                 const Vector3 &c
         );

  Plane3(const Vector3 &normal,
                 const Vector3 &point
                 );

  void ReverseOrientation()
  {
          mNormal *= -1;
          mD *= -1;
  }

  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, const 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;

  friend bool
  PlaneIntersection(const Plane3 &a, const Plane3 &b, const Plane3 &c, Vector3 &result);
  
  friend ostream &operator<<(ostream &s, const Plane3 p) {
    s<<p.mNormal<<" "<<p.mD;
    return s;
  }

  
};
  

/** A definition for an axis aligned plane.
*/
struct AxisAlignedPlane
{
public:
        AxisAlignedPlane(){}
        AxisAlignedPlane(const int axis, const float position):
          mAxis(axis), mPosition(position), mOrientation(false)
          {
          }
        Plane3 GetPlane() const
        {
                Vector3 normal(0,0,0); normal[mAxis] = mOrientation ? 1.0f : -1.0f;
                Vector3 point(0,0,0); point[mAxis] = mPosition;

        return Plane3(normal, point);
        }

        /// the split axis: one of 0=x, 1=y, 2=z
        int mAxis;
        /// the absolute position of the split axis
        float mPosition;
        /// the plane orientation
        bool mOrientation;

        friend ostream &operator<<(ostream &s, const AxisAlignedPlane &p) 
        {
                s << "a: " << p.mAxis << " p: " << p.mPosition;
                return s;
        }
};
}
#endif