Making progress on the SnapPlane() and SnapNormal() issues.

- Removing DIST_EPSILON	#define	from map.c.  It's unused and only confuses
programmers.

- Adding new function SnapPlaneImproved() to map.c which is like
SnapPlane(), only it takes an additional argument which	is the "center".
This new function is not being used anywhere yet.

- In mathlib, adding VectorIsOnAxis() and VectorIsOnAxialPlane(), two
convenience methods that will help make	other code look	more intuitive.


git-svn-id: svn://svn.icculus.org/gtkradiant/GtkRadiant/branches/Rambetter-math-fix-experiments@400 8a3a26a2-13c4-0310-b231-cf6edde360e5

libs/mathlib.h

@@ -82,6 +82,9 @@ qboolean VectorCompare (vec3_t v1, vec3_t v2);
 
 #define Q_rint(in) ((vec_t)floor(in+0.5))
 
+qboolean VectorIsOnAxis(vec3_t v);
+qboolean VectorIsOnAxialPlane(vec3_t v);
+
 vec_t VectorLength(vec3_t v);
 
 void VectorMA( const vec3_t va, vec_t scale, const vec3_t vb, vec3_t vc );

libs/mathlib/mathlib.c

@@ -26,6 +26,54 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
 vec3_t vec3_origin = {0.0f,0.0f,0.0f};
 
+/*
+================
+VectorIsOnAxis
+================
+*/
+qboolean VectorIsOnAxis(vec3_t v)
+{
+	int	i, zeroComponentCount;
+
+	zeroComponentCount = 0;
+	for (i = 0; i < 3; i++)
+	{
+		if (v[i] == 0.0)
+		{
+			zeroComponentCount++;
+		}
+	}
+
+	if (zeroComponentCount > 1)
+	{
+		// The zero vector will be on axis.
+		return qtrue;
+	}
+
+	return qfalse;
+}
+
+/*
+================
+VectorIsOnAxis
+================
+*/
+qboolean VectorIsOnAxialPlane(vec3_t v)
+{
+	int	i;
+
+	for (i = 0; i < 3; i++)
+	{
+		if (v[i] == 0.0)
+		{
+			// The zero vector will be on axial plane.
+			return qtrue;
+		}
+	}
+
+	return qfalse;
+}
+
 /*
 ================
 MakeNormalVectors

tools/quake3/q3map2/map.c

@@ -59,8 +59,6 @@ PlaneEqual()
 ydnar: replaced with variable epsilon for djbob
 */
 
-#define	DIST_EPSILON	0.01
-
 qboolean PlaneEqual( plane_t *p, vec3_t normal, vec_t dist )
 {
 	float	ne, de;
@@ -291,6 +289,30 @@ void SnapPlane( vec3_t normal, vec_t *dist )
 		*dist = Q_rint( *dist );
 }
 
+/*
+SnapPlaneImproved()
+snaps a plane to normal/distance epsilons, improved code
+*/
+void SnapPlaneImproved(vec3_t normal, vec_t *dist, vec3_t center)
+{
+	vec_t	distNearestInt;
+
+	if (SnapNormal(normal))
+	{
+		*dist = DotProduct(normal, center);
+	}
+
+	if (VectorIsOnAxis(normal))
+	{
+		// Only snap distance if the normal is an axis.  Otherwise there
+		// is nothing "natural" about snapping the distance to an integer.
+		distNearestInt = Q_rint(*dist);
+		if (-distanceEpsilon < *dist - distNearestInt && *dist - distNearestInt < distanceEpsilon)
+		{
+			*dist = distNearestInt;
+		}
+	}
+}
 
 
 /*