X-Git-Url: https://git.dogcows.com/gitweb?p=chaz%2Fyoink;a=blobdiff_plain;f=src%2FMoof%2FPlane.hh;h=b39891790f16a6afc682c9e753642cf8015ebd5e;hp=248a3128161afe0cadbdde10fa781d6b3e89c405;hb=3f6e44698c38b74bb622ad81ea9d2daa636981d2;hpb=72d4af22710317acffab861421c4364b1780b6fe

diff --git a/src/Moof/Plane.hh b/src/Moof/Plane.hh
index 248a312..b398917 100644
--- 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;
 };