Move Stats to its own module

Move Stats to its own module and pass it around to the intersection methods to keep track of how many tests and successful intersections there are.

src/objectPlane.cc

@@ -60,7 +60,8 @@ Plane::SetDistance(Double distance)
  */
 bool
 Plane::DoesIntersect(const Ray &ray,
-                     TVector& t)
+                     TVector& t,
+                     Stats& stats)
     const
 {
     /*
@@ -70,7 +71,7 @@ Plane::DoesIntersect(const Ray &ray,
      *
      *     A * x + B * y + C * z + D = 0, where
      *     A^2 + B^2 + C^2 = 1.
-     * 
+     *
      * The sign of D determines which side of the origin the plane is on.
      *
      * We can figure out the distance from the ray's origin to the intersection
@@ -80,7 +81,7 @@ Plane::DoesIntersect(const Ray &ray,
      * indicated with lowercase letters (ROx is the x component of RO).
      *
      *     A(ROx + RDx * t) + B(ROy + RDy * t) + C(ROz + RDz * t) + D = 0
-     * 
+     *
      * We then solve for t.
      *
      *     t = -(A * ROx + B * ROy + C * ROz + D) / (A * RDx + B * RDy + C * RDz)
@@ -90,6 +91,8 @@ Plane::DoesIntersect(const Ray &ray,
      *     t = -(n . RO + D) / (n . RD)
      */
 
+    stats.planeIntersectionTests++;
+
     /* The denominator for the t equation above. */
     Double vd = mNormal.dot(ray.direction);
     if (NearZero(vd)) {
@@ -110,6 +113,7 @@ Plane::DoesIntersect(const Ray &ray,
         return false;
     }
 
+    stats.planeIntersections++;
     t.push_back(t0);
     return true;
 }