added warnings and missing function

include/box2d/collision.h

@@ -251,6 +251,7 @@ B2_API b2CastOutput b2ShapeCastSegment(const b2ShapeCastInput* input, const b2Se
 B2_API b2CastOutput b2ShapeCastPolygon(const b2ShapeCastInput* input, const b2Polygon* shape);
 
 /// A convex hull. Used to create convex polygons.
+///	@warning Do not modify these values directly, instead use b2ComputeHull()
 typedef struct b2Hull
 {
 	/// The final points of the hull
@@ -267,6 +268,7 @@ typedef struct b2Hull
 /// - less than 3 points
 /// - more than b2_maxPolygonVertices points
 /// This welds close points and removes collinear points.
+///	@warning Do not modify a hull once it has been computed
 B2_API b2Hull b2ComputeHull(const b2Vec2* points, int32_t count);
 
 /// This determines if a hull is valid. Checks for:

src/distance_joint.c

@@ -40,6 +40,12 @@ void b2DistanceJoint_EnableLimit(b2JointId jointId, bool enableLimit)
 	joint->enableLimit = enableLimit;
 }
 
+bool b2DistanceJoint_IsLimitEnabled(b2JointId jointId)
+{
+	b2JointSim* joint = b2GetJointSimCheckType(jointId, b2_distanceJoint);
+	return joint->distanceJoint.enableLimit;
+}
+
 void b2DistanceJoint_SetLengthRange(b2JointId jointId, float minLength, float maxLength)
 {
 	b2JointSim* base = b2GetJointSimCheckType(jointId, b2_distanceJoint);