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:
   9
  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.
  15
  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
  18  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  19  DISCLAIMED.  IN  NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  20  FOR  ANY  DIRECT,  INDIRECT,  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  DAMAGES  (INCLUDING,  BUT  NOT  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  22  SERVICES;  LOSS  OF  USE,  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  23  CAUSED  AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  24  OR  TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  25  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26
  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.set(0.0, 0.0, 0.0);
  83                                 //intersection.normal = normal;
  84                                 return SCALAR(0.0);
  85                         }
  86
  87                         // no solution
  88                         return SCALAR(-1.0);
  89                 }
  90
  91                 Scalar distance = cml::dot(ray.point, normal) + d;
  92                 Scalar t = -distance / denominator;
  93                 if (t > SCALAR(0.0))
  94                 {
  95                         ray.solve(intersection.point, t);
  96
  97                         if (distance >= 0.0) intersection.normal = normal;
  98                         else                 intersection.normal = -normal;
  99                 }
 100
 101                 return t;
 102         }
 103
 104
 105         /* Causes the normal of the plane to become normalized.  The scalar may also
 106          * be changed to keep the equation true.  Word to the wise: don't normalize
 107          * a plane if the normal is the zero vector. */
 108         void normalize()
 109         {
 110                 Scalar mag = normal.length();
 111
 112                 normal /= mag;
 113                 d /= mag;
 114         }
 115
 116         /**
 117          * Determine the shortest distance between a point and the plane. */
 118
 119         Scalar getDistanceToPoint(const Vector3& point) const
 120         {
 121                 return cml::dot(point, normal) + d;
 122         }
 123
 124         Halfspace intersects(const Vector3& point) const
 125         {
 126                 Scalar distance = getDistanceToPoint(point);
 127
 128                 if (isEqual(distance, 0.0)) return INTERSECT;
 129                 else if (distance < 0.0)    return NEGATIVE;
 130                 else                        return POSITIVE;
 131         }
 132
 133         Halfspace intersects(const Aabb<3>& aabb) const;
 134         Halfspace intersects(const Sphere<3>& sphere) const;
 135 };
 136
 137
 138 } // namespace Mf
 139
 140 #endif // _MOOF_PLANE_HH_
 141
 142 /** vim: set ts=4 sw=4 tw=80: *************************************************/
 143