Fix NAN error in getAngle of vector2d, patch by Rocko Bonaparte

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@3743 dfc29bdd-3216-0410-991c-e03cc46cb475

include/vector2d.h

@@ -213,24 +213,23 @@ public:
 			return Y < 0 ? 90 : 270;
 
 		// don't use getLength here to avoid precision loss with s32 vectors
-		f64 tmp = Y / sqrt((f64)(X*X + Y*Y));
-		if ( tmp > 1.0 ) //   avoid floating-point trouble as sqrt(y*y) is occasionally larger y
-			tmp = 1.0;
-		tmp = atan( core::squareroot(1 - tmp*tmp) / tmp) * RADTODEG64;
+		// avoid floating-point trouble as sqrt(y*y) is occasionally larger than y, so clamp
+		const f64 tmp = core::clamp(Y / sqrt((f64)(X*X + Y*Y)), -1.0, 1.0);
+		const f64 angle = atan( core::squareroot(1 - tmp*tmp) / tmp) * RADTODEG64;
 
 		if (X>0 && Y>0)
-			return tmp + 270;
+			return angle + 270;
 		else
 		if (X>0 && Y<0)
-			return tmp + 90;
+			return angle + 90;
 		else
 		if (X<0 && Y<0)
-			return 90 - tmp;
+			return 90 - angle;
 		else
 		if (X<0 && Y>0)
-			return 270 - tmp;
+			return 270 - angle;
 
-		return tmp;
+		return angle;
 	}
 
 	//! Calculates the angle between this vector and another one in degree.