Fix llEuler2Rot's sign.

LL's algorithm for llEuler2Rot involves calculating a rotation matrix from the Eulers, then transforming the rotation matrix to quaternion. This generates sign discrepancies with our direct quaternion calculation algorithm.

Fixed by making only the necessary calculations to find the correct sign. Unfortunately, they are still heavy (notably, six more trig functions).

lslopt/lslbasefuncs.py

@@ -1071,10 +1071,29 @@ def llEuler2Rot(v):
     c2 = math.cos(v[2]*0.5)
     s2 = math.sin(v[2]*0.5)
 
-    return Quaternion(F32((s0 * c1 * c2 + c0 * s1 * s2,
-                           c0 * s1 * c2 - s0 * c1 * s2,
-                           c0 * c1 * s2 + s0 * s1 * c2,
-                           c0 * c1 * c2 - s0 * s1 * s2)))
+    r = F32((s0 * c1 * c2 + c0 * s1 * s2,
+             c0 * s1 * c2 - s0 * c1 * s2,
+             c0 * c1 * s2 + s0 * s1 * c2,
+             c0 * c1 * c2 - s0 * s1 * s2))
+
+    # Fix the sign
+    c0 = math.cos(v[0])
+    s0 = math.sin(v[0])
+    c1 = math.cos(v[1])
+    s1 = math.sin(v[1])
+    c2 = math.cos(v[2])
+    s2 = math.sin(v[2])
+    d1 = c1*c2
+    d2 = c0*c2 - s0*s1*s2
+    d3 = c0*c1
+    if d1 + d2 + d3 > 0:
+        return Quaternion(-f for f in r) if r[3] < 0 else Quaternion(r)
+    i = 0
+    if d2 > d1:
+        i = 1
+    if d1 < d3 > d2:
+        i = 2
+    return Quaternion(-f for f in r) if r[i] < 0 else Quaternion(r)
 
 def llFabs(f):
     assert isfloat(f)