Bendy Bones Instability Fix - Second Attempt

So the error seems to be in cubic_tangent_factor_circle_v3(),
which was introduced with D2001.

I've tweaked the most obvious culprit here - the epsilon factor.
It used to be 10^-7, but I've reduced it down to 10^-5 now,
and it's looking a lot more stable now :)

---------

BTW, about the derivation of the magic 0.390464 factor I briefly subbed back
as a workaround for this bug, see:
    http://www.whizkidtech.redprince.net/bezier/circle/

1 files changed, 1 insertions, 5 deletions

diff --git a/source/blender/blenkernel/intern/armature.c b/source/blender/blenkernel/intern/armature.c
index 99c9d0a0a79..b59618f46b2 100644
--- a/source/blender/blenkernel/intern/armature.c
+++ b/source/blender/blenkernel/intern/armature.c
@@ -634,11 +634,7 @@ void b_bone_spline_setup(bPoseChannel *pchan, int rest, Mat4 result_array[MAX_BB
 	}
 
 	{
-#if 0 // <--- this is currently unstable, disabling until we find a good fix
-		const float circle_factor = length * (cubic_tangent_factor_circle_v3(h1, h2) / 0.75f);  
-#else // <--- temporary workaround, using the old hardcoded value
-		const float circle_factor = length * 0.390464f;  
-#endif
+		const float circle_factor = length * (cubic_tangent_factor_circle_v3(h1, h2) / 0.75f);
 
 		const float hlength1 = bone->ease1 * circle_factor;
 		const float hlength2 = bone->ease2 * circle_factor;