[Bf-committers] PATCH: Avoid throwing an assert for IK constraint.

[Kester Maddock]

This patch stops blender from crashing when creating an IK constraint:
To reproduce:
Add an armature.
Add three bones (upper arm, forearm, hand)
Extrude an IK controller from the wrist.
Switch to pose mode.
Select the hand bone and create an IK constraint.
Type the armature's name ("Armature") into the object box.
Blender assertion !MT_FuzzyZero fails.

This is because in IK_QJacobianSolver.cpp function 
IK_QJacobianSolver::Solve goal_dir.normalize(); is executed with 
goal_dir == {0., 0., 0.}

This patch checks for that condition.

Kester



Index: intern/iksolver/intern/IK_QJacobianSolver.cpp
===================================================================
RCS file: 
/cvsroot/bf-blender/blender/intern/iksolver/intern/IK_QJacobianSolver.cpp,v
retrieving revision 1.4
diff -u -3 -b -B -r1.4 IK_QJacobianSolver.cpp
--- intern/iksolver/intern/IK_QJacobianSolver.cpp       1 May 2003 
19:52:20 -0000       1.4
+++ intern/iksolver/intern/IK_QJacobianSolver.cpp       26 Nov 2003 
03:36:52 -0000
@@ -65,6 +65,7 @@

        MT_Vector3 goal_dir = g_position - segs[0].GlobalSegmentStart();

+       if (goal_dir.length() < tolerance) return false;

        const MT_Scalar chain_max_extension = chain.MaxExtension();