Fix for commit from Brecht:

2006/11/19 00:07:32 CET
Fix for bug #5250: inaccurate conversion between edit and pose mode bones.

Two very bad bugs:
- replacing atan() with atan2() should also remove the M_PI correction!
  This is the equivalent:
    angle=atan(x/y); if(y<0) angle+=M_PI;
    angle= atan2(x, y);

- the new NormalizedVecAngle2() call was negating an input vector, causing
  calling code to screw up. All arithb.c calls should not alter input.

1 files changed, 6 insertions, 4 deletions

diff --git a/source/blender/blenlib/intern/arithb.c b/source/blender/blenlib/intern/arithb.c
index 51000b3b155..fd91a4231f6 100644
--- a/source/blender/blenlib/intern/arithb.c
+++ b/source/blender/blenlib/intern/arithb.c
@@ -2418,11 +2418,13 @@ float NormalizedVecAngle2(float *v1, float *v2)
 {
 	/* this is the same as acos(Inpf(v1, v2)), but more accurate */
 	if (Inpf(v1, v2) < 0.0f) {
-		v2[0]= -v2[0];
-		v2[1]= -v2[1];
-		v2[2]= -v2[2];
+		float vec[3];
+		
+		vec[0]= -v2[0];
+		vec[1]= -v2[1];
+		vec[2]= -v2[2];
 
-		return (float)M_PI - 2.0f*saasin(VecLenf(v2, v1)/2.0f);
+		return (float)M_PI - 2.0f*saasin(VecLenf(vec, v1)/2.0f);
 	}
 	else
 		return 2.0f*saasin(VecLenf(v2, v1)/2.0);