cade lab fixes

[chaz/yoink] / src / Moof / Plane.hh

diff --git a/src/Moof/Plane.hh b/src/Moof/Plane.hh
index 248a3128161afe0cadbdde10fa781d6b3e89c405..b39891790f16a6afc682c9e753642cf8015ebd5e 100644 (file)
--- a/src/Moof/Plane.hh
+++ b/src/Moof/Plane.hh
@@ -28,18 +28,24 @@
 
 #ifndef _MOOF_PLANE_HH_
 #define _MOOF_PLANE_HH_
-       
+
 #include <Moof/Math.hh>
+#include <Moof/Shape.hh>
 
 
 namespace Mf {
 
 
-class Aabb;
-class Sphere;
+template <int D> class Aabb;
+template <int D> 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
+struct Plane : public Shape<3>
 {
        Vector3 normal;
        Scalar  d;
@@ -60,6 +66,40 @@ struct Plane
                d(scalar) {}
 
 
+       bool intersectRay(const Ray<3>& ray, Ray<3>::Intersection& hit)
+       {
+               // solve: [(ray.point + t*ray.direction) dot normal] + d = 0
+
+               Scalar denom = cml::dot(ray.direction, normal);
+
+               // check for parallel condition
+               if (denom == SCALAR(0.0))
+               {
+                       if (isEqual(cml::dot(ray.point, normal), -d))
+                       {
+                               // the ray lies on the plane
+                               hit.distance = SCALAR(0.0);
+                               hit.normal.set(0.0, 0.0, 0.0);
+                               return true;
+                       }
+
+                       // no solution
+                       return false;
+               }
+
+               Scalar numer = cml::dot(ray.point, normal) + d;
+               hit.distance = -numer / denom;
+               if (hit.distance < SCALAR(0.0)) return false;
+
+               if (numer >= 0.0) hit.normal = normal;
+               else              hit.normal = -normal;
+               return true;
+       }
+
+
+       /* Causes the normal of the plane to become normalized.  The scalar may also
+        * be changed to keep the equation true.  Word to the wise: don't normalize
+        * a plane if the normal is the zero vector. */
        void normalize()
        {
                Scalar mag = normal.length();
@@ -68,12 +108,15 @@ struct Plane
                d /= mag;
        }
 
-       inline Scalar getDistanceToPoint(const Vector3& point) const
+       /**
+        * Determine the shortest distance between a point and the plane. */
+
+       Scalar getDistanceToPoint(const Vector3& point) const
        {
                return cml::dot(point, normal) + d;
        }
 
-       inline Halfspace intersectsPoint(const Vector3& point) const
+       Halfspace intersects(const Vector3& point) const
        {
                Scalar distance = getDistanceToPoint(point);
 
@@ -82,8 +125,8 @@ struct Plane
                else                        return POSITIVE;
        }
 
-       Halfspace intersectsAabb(const Aabb& aabb) const;
-       Halfspace intersectsSphere(const Sphere& sphere) const;
+       Halfspace intersects(const Aabb<3>& aabb) const;
+       Halfspace intersects(const Sphere<3>& sphere) const;
 };