[Yake-svn] SF.net SVN: yake:[1929] trunk/yake/yake/base/math

[<psy...@us...>]

Revision: 1929
          http://yake.svn.sourceforge.net/yake/?rev=1929&view=rev
Author:   psyclonist
Date:     2008-07-24 18:47:30 +0000 (Thu, 24 Jul 2008)

Log Message:
-----------
* [base/math] added Plane::distanceTo()
* [base/math] added Plane c'tor: from 3 points
* [base/math] added intersect(Plane,Ray)

Modified Paths:
--------------
    trunk/yake/yake/base/math/yakePlane.h
    trunk/yake/yake/base/math/yakeRay.h

Modified: trunk/yake/yake/base/math/yakePlane.h
===================================================================
--- trunk/yake/yake/base/math/yakePlane.h	2008-06-30 20:25:46 UTC (rev 1928)
+++ trunk/yake/yake/base/math/yakePlane.h	2008-07-24 18:47:30 UTC (rev 1929)
@@ -33,22 +33,58 @@
 #endif
 #include "yakeMath.h"
 #include "yakeVector3.h"
+#include "yakeRay.h"
 
 namespace yake {
 namespace math {
 
+	/** Represents a plane in space. */
 	class YAKE_BASE_API Plane
 	{
 	public:
+		/** @param kD distance (from the plane to the origin) in direction of rkNormal */
 		Plane( const Vector3 & rkNormal, const real kD ) : normal( rkNormal ), d( kD )
 		{
 		}
+		Plane(const Point3& p0, const Point3& p1, const Point3& p2) :
+			normal((p1-p0).crossProduct(p2-p0).normalisedCopy()), d(-normal.dotProduct(p0.asVector()))
+		{
+		}
+		/** Positive if plane faces the point,
+			negative if it's on the other side ("behind" the plane).
+			@note d=(pt-p0).n
+			@note n.pt+D
+		*/
+		real distanceTo(const Point3& pt) const
+		{
+			return (normal.dotProduct(pt.asVector()) + d);
+		}
 
 		Vector3		normal;
 		real		d;
 	};
 
-}
-}
+	/** Intersects a ray with a plane (if possible) and returns
+		the parameter on the ray which can be used to calculate
+		the intersection point.
+		@return result.first is true if the ray intersects. result.second is
+			the length along the ray which can be used to calculate the
+			intersection point like this: intPt= ray.origin + ray.direction * result.second
+			or intPt= ray.getPoint(result.second).
+		@note The returned length can be negative!
+	*/
+	inline std::pair<bool,real> intersect(const Plane& plane, const Ray& ray)
+	{
+		const real denom = plane.normal.dotProduct(ray.direction());
+		if (fabs(denom)<0.0001) //@todo use a proper EPS
+			return std::make_pair(false,0);
 
+		const real nom = plane.normal.dotProduct(ray.origin().asVector()) + plane.d;
+		const real s = - (nom / denom);
+		return (s >= 0.) ? std::make_pair(true,s) : std::make_pair(false,0);
+	}
+} // namespace math
+using math::Plane;
+} // namespace yake
+
 #endif

Modified: trunk/yake/yake/base/math/yakeRay.h
===================================================================
--- trunk/yake/yake/base/math/yakeRay.h	2008-06-30 20:25:46 UTC (rev 1928)
+++ trunk/yake/yake/base/math/yakeRay.h	2008-07-24 18:47:30 UTC (rev 1929)
@@ -39,6 +39,7 @@
 namespace yake {
 namespace math {
 
+	/** Represents a ray; from a point along a direction. */
 	class YAKE_BASE_API Ray
 	{
 	public:
@@ -52,6 +53,14 @@
 		{
 			return mOrigin;
 		}
+		const Vector3& direction() const
+		{
+			return mDirection;
+		}
+		const Point3& origin() const
+		{
+			return mOrigin;
+		}
 		const Vector3& getDirection() const
 		{
 			return mDirection;
@@ -64,11 +73,14 @@
 		{
 			mDirection = rDirection;
 		}
+		/** Evaluate the parameter s (i.e. length here)
+			along the ray.
+			@note s may be negative.
+		*/
 		Point3 getPoint( const real s ) const
 		{
 			return (mOrigin + (mDirection * s));
 		}
-		std::pair<bool, real> intersects(const Plane& plane) const;
 
 	private:
 		Point3		mOrigin;


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