Crash in Octree::grow_to_accomodate

[Kristoffer Sjöö]

I'm getting crashes in Peekabot 0.7.2 after I added the following esoteric code to my program:

   peekabot::CylinderProxy normp;
   normp.add(m_onnessTester, "Normal", peekabot::REPLACE_ON_CONFLICT);
   normp.set_color(0,0,1);
   normp.set_scale(0.005, 0.005, 0.1);
   normp.translate(0.05,0,0);
   normp.set_orientation(witness.normal.x, witness.normal.y, witness.normal.z);
   normp.rotate(M_PI/2, 0, 1, 0);
   normp.translate(witness.point1.x, witness.point1.y, witness.point1.z,
       peekabot::PARENT_COORDINATES);

The error I get is

peekabot: renderer/Octree.cc:245: peekabot::renderer::Octree::OctreeNode* peekabot::renderer::Octree::grow_to_accomodate(const peekabot::renderer::CullableEntity*): Assertion `index != -1' failed.

The values sent to set_orientation above are (-1,0,0) when the crash happens. The translate arguments evaluate to (-0.115, 0.04499999999998, 1.2599999713897705). I have copied the above code to the beginning of my execution and replaced the arguments by constants as above; the same result occurs so it's not dependent on the state of the system or Peekabot.
Taking out the set_orientation line averts the crash.

[Staffan Gimåker (gimaker)]

Fixed in the 0.7.x branch.

Note that setting the orientation in this particular case (when the original orientation is parallel to the desired orientation) is ambiguous. I added some documentation stating how this ambiguity is resolved; we choose to always rotate about the object's Z axis in case of ambiguity. E.g. calling set_orientation(-1, 0, 0) on an object with the axes x=(1,0,0), y=(0,1,0) and z=(0,0,1) will yield x'=(-1,0,0), y'=(0,-1,0) and z'=(0,0,1).

[Kristoffer Sjöö (krsj)]

I wasn't too concerned about the exact outcome, given the object in question :) But disambiguation is always good.