From 31a1590db0bbfee2f81052b6eaa845f8ed93e96d Mon Sep 17 00:00:00 2001
From: Brecht Van Lommel <brechtvanlommel@pandora.be>
Date: Tue, 29 Jan 2008 09:44:26 +0000
Subject: [PATCH] Bugfix: quaternion angle calculation in python used the acos
 function. This gives nan if the input is e.g. 1.00000001 due to rounding
 errors, better is to use saacos (safe acos) that checks for the range first.

---
 source/blender/python/api2_2x/Mathutils.c | 7 ++-----
 source/blender/python/api2_2x/quat.c      | 6 +++---
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/source/blender/python/api2_2x/Mathutils.c b/source/blender/python/api2_2x/Mathutils.c
index cf79b3071f7..65ae46ffccd 100644
--- a/source/blender/python/api2_2x/Mathutils.c
+++ b/source/blender/python/api2_2x/Mathutils.c
@@ -1,5 +1,5 @@
 /* 
- * $Id: Mathutils.c 11502 2007-08-06 14:27:08Z khughes $
+ * $Id$
  *
  * ***** BEGIN GPL/BL DUAL LICENSE BLOCK *****
  *
@@ -500,10 +500,7 @@ PyObject *M_Mathutils_AngleBetweenVecs(PyObject * self, PyObject * args)
 	}
 	dot /= (sqrt(test_v1) * sqrt(test_v2));
 
-	if (dot < -1.0f || dot > 1.0f) {
-		CLAMP(dot,-1.0f,1.0f);
-	}
-	angleRads = (double)acos(dot);
+	angleRads = (double)saacos(dot);
 
 	return PyFloat_FromDouble(angleRads * (180/ Py_PI));
 
diff --git a/source/blender/python/api2_2x/quat.c b/source/blender/python/api2_2x/quat.c
index 19e749f187c..a4a99c28d72 100644
--- a/source/blender/python/api2_2x/quat.c
+++ b/source/blender/python/api2_2x/quat.c
@@ -1,5 +1,5 @@
 /*
- * $Id: quat.c 12314 2007-10-20 20:24:09Z campbellbarton $
+ * $Id$
  *
  * ***** BEGIN GPL/BL DUAL LICENSE BLOCK *****
  *
@@ -184,13 +184,13 @@ static PyObject *Quaternion_getattr(QuaternionObject * self, char *name)
 	}
 	if(STREQ(name, "angle")) {
 		mag = self->quat[0];
-		mag = 2 * (acos(mag));
+		mag = 2 * (saacos(mag));
 		mag *= (180 / Py_PI);
 		return PyFloat_FromDouble(mag);
 	}
 	if(STREQ(name, "axis")) {
 		mag = self->quat[0] * (Py_PI / 180);
-		mag = 2 * (acos(mag));
+		mag = 2 * (saacos(mag));
 		mag = sin(mag / 2);
 		for(x = 0; x < 3; x++) {
 			vec[x] = (float)(self->quat[x + 1] / mag);