I have an IK chain. I added a track to another bone to control where the middle of the chain points to. I’m extremely confused by the settings. Most of all the target space thing. It seems like the only thing that can ever point properly to the target is the other end of the chain. If someone can explain this to me, I’d be grateful.
I’m not asking about OBJECTS tracking nor CAMERAS tracking. I’m confused by the TRACK TO in POSE MODE thanks. I can’t make heads or tails of it. It seems to always point at random places instead of tracking correctly. Just clarifying because I’ve been searching for a long time on this and I’m kinda tired of every result being about the camera tracking instead of track to within pose mode.
I whipped up a sample file and attached it, I had blender 2.49b open at the time, but the same should work for 2.5. It’s a 2 bone IK chain, think of an IK leg… The track to constraint is on the upperleg bone and works to point the knee of the leg at the knee target. This, of course is silly, since the IK constraint has the pole target to accomplish the same thing, but it was the only thing I could think of.
You’re very nice, but I already know how to pick 2 bones and chose target to. This doesn’t explain to me what the controls (POS, ROT, To: Up: Target, Head/Tail: etc) are meant to do.
It seems to me like the chain can only track left and right, even on the chain example you give, it seems like the bone isn’t tracking in 3D space as soon as the end effector of the IK chain is it straight under the body. It seems to only track XY and then Z is totally random. Thank you.
the head, tail properties control what part of the bone your actually tracking to. by default the track to contraint will track to the fat part of the bone but if u set the head tail influence to one the bone with a track to contraint will point to the thin part of the bone its pointing to.
i’m not 100 % sure what to and up do exactly but they definately affect how the bone is tracking in 3d space (world, local, pose pose w parent). i’ll do a little research on it after my art history class and get back to u on wat these features do
The Up: field is what axis of the bone points in the world’s positive z-axis. The To: field is what axis of the constrained bone points to the target bone. See first 3 screenshots.
The Target checkbox (blender 2.5x) or Align:Target (2.4x) tells the constraint to use the target’s z-axis instead of the world’s z-axis for the Up: field. In the 4th screenshot, the target box is checked and now the bone’s x-axis (indicated in the Up: field) is pointing in the direction of the target bones z-axis, not the world axis.
The Head/Tail field tells the constrained bone to point to the target’s head (fat end) or the target’s tail (skinny end).
The Space (2.5x) or CSpace (2.4x) is how the constraint is evaulated, be it world space, local space, etc, etc. This is the same as all other constraints. The influence field is how much the constrained bone is influenced by the constraint, here again, it’s the same as all other constraints
I’m afraid my previous example was a poor one, as it had two constraints at work, this can be confusing. The IK constraint will override all other constraints (or at least all that I can think of atm).
Two relevant webpages that describe this are here and here.
I think it’s best to just set up a 2 bone example file and use the constraint on one bone to study how the various settings effect the bone. Turn on display of the bone’s axis to view how the changes affect things. Another quick note: you cannot have the To: field and the Up: field set to the same axis. Which common sense should tell you that you cannot have the y-axis of a bone pointing upwards and pointing at a target bone that is to the left of the constrained bone at the same time. In 2.4x if you attempt this, the name field of the constraint will turn red to indicate the constraint is broken.
