Dogcows Code - chaz/yoink/blob - src/Moof/Plane.hh

   1
   2 /*******************************************************************************
   3
   4  Copyright (c) 2009, Charles McGarvey
   5  All rights reserved.
   6
   7  Redistribution   and   use  in  source  and  binary  forms,  with  or  without
   8  modification, are permitted provided that the following conditions are met:
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  10    * Redistributions  of  source  code  must retain the above copyright notice,
  11      this list of conditions and the following disclaimer.
  12    * Redistributions  in binary form must reproduce the above copyright notice,
  13      this  list of conditions and the following disclaimer in the documentation
  14      and/or other materials provided with the distribution.
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  16  THIS  SOFTWARE  IS  PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  17  AND  ANY  EXPRESS  OR  IMPLIED  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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  19  DISCLAIMED.  IN  NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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  27 *******************************************************************************/
  28
  29 #ifndef _MOOF_PLANE_HH_
  30 #define _MOOF_PLANE_HH_
  31
  32 #include <Moof/Math.hh>
  33 #include <Moof/Shape.hh>
  34
  35
  36 namespace Mf {
  37
  38
  39 template <int D> class Aabb;
  40 template <int D> class Sphere;
  41
  42
  43 /*
  44  * A plane in 3-space defined by the equation Ax + By + Cz = D, where [A, B, C]
  45  * is normal to the plane.
  46  */
  47
  48 struct Plane : public Shape<3>
  49 {
  50         Vector3 normal;
  51         Scalar  d;
  52
  53         typedef enum
  54         {
  55                 NEGATIVE        = -1,
  56                 INTERSECT       =  0,
  57                 POSITIVE        =  1
  58         } Halfspace;
  59
  60         Plane() {}
  61         Plane(const Vector3& vector, Scalar scalar) :
  62                 normal(vector),
  63                 d(scalar) {}
  64         Plane(Scalar a, Scalar b, Scalar c, Scalar scalar) :
  65                 normal(a, b, c),
  66                 d(scalar) {}
  67
  68
  69         Scalar intersectRay(const Ray<3>& ray, Ray<3>::Intersection& intersection)
  70         {
  71                 // solve: [(ray.point + t*ray.direction) dot normal] + d = 0
  72
  73                 Scalar denominator = cml::dot(ray.direction, normal);
  74
  75                 // check for parallel condition
  76                 if (denominator == SCALAR(0.0))
  77                 {
  78                         if (isEqual(cml::dot(ray.point, normal), -d))
  79                         {
  80                                 // the ray lies on the plane
  81                                 intersection.point = ray.point;
  82                                 intersection.normal = normal;
  83                                 return SCALAR(0.0);
  84                         }
  85
  86                         // no solution
  87                         return SCALAR(-1.0);
  88                 }
  89
  90                 Scalar t = (cml::dot(ray.point, normal) + d) / denominator;
  91                 if (t > SCALAR(0.0))
  92                 {
  93                         ray.solve(intersection.point, t);
  94                         intersection.normal = normal;
  95                 }
  96
  97                 return t;
  98         }
  99
 100
 101         /* Causes the normal of the plane to become normalized.  The scalar may also
 102          * be changed to keep the equation true.  Word to the wise: don't normalize
 103          * a plane if the normal is the zero vector. */
 104         void normalize()
 105         {
 106                 Scalar mag = normal.length();
 107
 108                 normal /= mag;
 109                 d /= mag;
 110         }
 111
 112         /**
 113          * Determine the shortest distance between a point and the plane. */
 114
 115         Scalar getDistanceToPoint(const Vector3& point) const
 116         {
 117                 return cml::dot(point, normal) + d;
 118         }
 119
 120         Halfspace intersects(const Vector3& point) const
 121         {
 122                 Scalar distance = getDistanceToPoint(point);
 123
 124                 if (isEqual(distance, 0.0)) return INTERSECT;
 125                 else if (distance < 0.0)    return NEGATIVE;
 126                 else                        return POSITIVE;
 127         }
 128
 129         Halfspace intersects(const Aabb<3>& aabb) const;
 130         Halfspace intersects(const Sphere<3>& sphere) const;
 131 };
 132
 133
 134 } // namespace Mf
 135
 136 #endif // _MOOF_PLANE_HH_
 137
 138 /** vim: set ts=4 sw=4 tw=80: *************************************************/
 139