X-Git-Url: https://git.dogcows.com/gitweb?p=chaz%2Fyoink;a=blobdiff_plain;f=src%2FMoof%2FPlane.hh;h=5ec59eab28e1c6115f4923b92892de9fd5e9d572;hp=797edc05c39fe13283c4a52088502fcb6e2f132c;hb=71bd9dbaf1c1e3c55a9f63392a73865d8aeee7d4;hpb=29e3d45f7bbbf31eadf793c41ff2b3d9c47b7539

diff --git a/src/Moof/Plane.hh b/src/Moof/Plane.hh
index 797edc0..5ec59ea 100644
--- a/src/Moof/Plane.hh
+++ b/src/Moof/Plane.hh
@@ -28,18 +28,106 @@
 
 #ifndef _MOOF_PLANE_HH_
 #define _MOOF_PLANE_HH_
-	
+
 #include <Moof/Math.hh>
+#include <Moof/Shape.hh>
 
 
 namespace Mf {
 
 
-class Plane
+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 : public Shape<3>
 {
-	Vector4 components;
+	Vector3	normal;
+	Scalar	d;
+
+	typedef enum
+	{
+		NEGATIVE	= -1,
+		INTERSECT	=  0,
+		POSITIVE	=  1
+	} Halfspace;
+
+	Plane() {}
+	Plane(const Vector3& vector, Scalar scalar) :
+		normal(vector),
+		d(scalar) {}
+	Plane(Scalar a, Scalar b, Scalar c, Scalar scalar) :
+		normal(a, b, c),
+		d(scalar) {}
+
+
+	Scalar intersectRay(const Ray<3>& ray, Ray<3>::Intersection& intersection)
+	{
+		// solve: [(ray.point + t*ray.direction) dot normal] + d = 0
+
+		Scalar denominator = cml::dot(ray.direction, normal);
+
+		// check for parallel condition
+		if (denominator == SCALAR(0.0))
+		{
+			if (isEqual(cml::dot(ray.point, normal), -d))
+			{
+				// the ray lies on the plane
+				intersection.point = ray.point;
+				intersection.normal = normal;
+				return SCALAR(0.0);
+			}
+
+			// no solution
+			return SCALAR(-1.0);
+		}
+
+		Scalar t = (cml::dot(ray.point, normal) + d) / denominator;
+		if (t > SCALAR(0.0))
+		{
+			ray.solve(intersection.point, t);
+			intersection.normal = normal;
+		}
+
+		return t;
+	}
+
+
+	/* 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();
+
+		normal /= mag;
+		d /= mag;
+	}
+
+	/**
+	 * Determine the shortest distance between a point and the plane. */
+
+	Scalar getDistanceToPoint(const Vector3& point) const
+	{
+		return cml::dot(point, normal) + d;
+	}
+
+	Halfspace intersects(const Vector3& point) const
+	{
+		Scalar distance = getDistanceToPoint(point);
+
+		if (isEqual(distance, 0.0)) return INTERSECT;
+		else if (distance < 0.0)    return NEGATIVE;
+		else                        return POSITIVE;
+	}
 
-public:
+	Halfspace intersects(const Aabb<3>& aabb) const;
+	Halfspace intersects(const Sphere<3>& sphere) const;
 };