X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=source%2Fgeometry%2Fhalfspace.h;h=b439851bd5adaf3a7067c7f91f5bf8308bb01166;hb=7919982691f0b8c69d8bef1bf6471b1e7a312163;hp=f671629e56194b0a93a00220c5ef17ef0c6ad0f7;hpb=fb9e6b5ff48e10ea2217cf539e0461956abf02cf;p=libs%2Fmath.git

diff --git a/source/geometry/halfspace.h b/source/geometry/halfspace.h
index f671629..b439851 100644
--- a/source/geometry/halfspace.h
+++ b/source/geometry/halfspace.h
@@ -7,8 +7,8 @@ namespace Msp {
 namespace Geometry {
 
 /**
-An infinite shape consisting of the space on one side of a plane.  Mostly
-useful when composited with other shapes.
+An unbounded shape consisting of the space on one side of a plane.  Mostly
+useful when intersected with other shapes.
 */
 template<typename T, unsigned D>
 class HalfSpace: public Shape<T, D>
@@ -63,7 +63,12 @@ inline bool HalfSpace<T, D>::contains(const LinAl::Vector<T, D> &point) const
 template<typename T, unsigned D>
 inline unsigned HalfSpace<T, D>::get_intersections(const Ray<T, D> &ray, SurfacePoint<T, D> *points, unsigned size) const
 {
-	T x = -inner_product(ray.get_start(), normal)/inner_product(ray.get_direction(), normal);
+	T d = inner_product(ray.get_start(), normal);
+	T c = inner_product(ray.get_direction(), normal);
+	if(c==T(0))
+		return 0;
+
+	T x = -d/c;
 	if(ray.check_limits(x))
 	{
 		if(points && size>0)
@@ -71,6 +76,7 @@ inline unsigned HalfSpace<T, D>::get_intersections(const Ray<T, D> &ray, Surface
 			points[0].position = ray.get_start()+ray.get_direction()*x;
 			points[0].normal = normal;
 			points[0].distance = x;
+			points[0].entry = (c<T(0));
 		}
 
 		return 1;