Fixed serious error in Intersection::planeLine().

The unit test was so weak that this parenthesis error wasn't spotted
until now. Updated the unit test to don't accept the previous code and
also floats everywhere instead of ints.

src/Math/Geometry/Intersection.h

@@ -59,7 +59,7 @@ class Intersection {
             T f = Vector3<T>::dot(planePosition, planeNormal);
 
             /* Compute t */
-            return (f-Vector3<T>::dot(planeNormal, a)/Vector3<T>::dot(planeNormal, b-a));
+            return (f-Vector3<T>::dot(planeNormal, a))/Vector3<T>::dot(planeNormal, b-a);
         }
 };
 

src/Math/Geometry/Test/IntersectionTest.cpp

@@ -29,25 +29,25 @@ namespace Magnum { namespace Math { namespace Geometry { namespace Test {
 typedef Magnum::Math::Vector3<float> Vector3;
 
 void IntersectionTest::planeLine() {
-    Vector3 planePosition;
+    Vector3 planePosition(-1.0f, 1.0f, 0.5f);
     Vector3 planeNormal(0.0f, 0.0f, 1.0f);
 
     /* Inside line segment */
     QCOMPARE((Intersection::planeLine(planePosition, planeNormal,
-        Vector3(0, 0, -1), Vector3(0, 0, 1))), 0.5f);
+        Vector3(0.0f, 0.0f, -1.0f), Vector3(0.0f, 0.0f, 1.0f))), 0.75f);
 
     /* Outside line segment */
     QCOMPARE((Intersection::planeLine(planePosition, planeNormal,
-        Vector3(0, 0, 1), Vector3(0, 0, 2))), -1.0f);
+        Vector3(0.0f, 0.0f, 1.0f), Vector3(0.0f, 0.0f, 2.0f))), -0.5f);
 
     /* Line lies on the plane */
     float nan = Intersection::planeLine(planePosition, planeNormal,
-        Vector3(1, 0, 0), Vector3(0, 1, 0));
+        Vector3(1.0f, 0.5f, 0.5f), Vector3(0.0f, 1.0f, 0.5f));
     QVERIFY(nan != nan);
 
     /* Line is parallell to the plane */
     QCOMPARE((Intersection::planeLine(planePosition, planeNormal,
-        Vector3(1, 0, 1), Vector3(0, 0, 1))), numeric_limits<float>::infinity());
+        Vector3(1.0f, 0.0f, 1.0f), Vector3(0.0f, 0.0f, 1.0f))), numeric_limits<float>::infinity());
 }
 
 }}}}