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View Full Version : Motion option, target item not working in 11.5, help please.



tonyhall007
03-05-2013, 04:15 AM
Hi
I have set my camera up to target a basic ball shape, which I have made a rigid body object so it will roll down a basic slope, then using the target item option in Lightwave 11.5, I have used the motion options, then target item options to track the object. The orange line appears and follows the object, but the camera does nothing, it does not target the object, but the orange line does and moves. Anyone else have this problem?

lino.grandi
03-05-2013, 05:03 AM
Same problem here. Looking into that. Thank you!

tonyhall007
03-05-2013, 05:09 AM
I have just tried to demonstrate this to 20 students, and at one stage I thought I was going mad. Glad its not just me having the problem. It works fine in Lightwave 11, as I have demonstrated it before. Hopefully its just a small thing to sort.

tonyhall007
03-05-2013, 05:34 AM
I have tried adding a null to the center of the ball and then parenting to the ball, then targeting the null, but the same thing happens. If you turn off the rigid dynamics and animated on the timeline it works. Strange one.

lino.grandi
03-05-2013, 04:29 PM
It's a motion evaulation order problem. The only solution at the moment would be to use Bakemotion on the rigid body you want to target.

tonyhall007
03-06-2013, 12:41 AM
Do you know if this is something that will be sorted in the next up-date? Thanks for your help.

jeric_synergy
03-06-2013, 01:30 AM
If you used DP kit to attach a Null to a point on the object (even a 'utility point', i.e. not really part of the mesh), you should be able to target the Null as DPKit moves it.

lino.grandi
03-06-2013, 03:38 AM
Do you know if this is something that will be sorted in the next up-date? Thanks for your help.

I can't promise, but we're looking into that.

In the meanwhile, I've found out that using the Parent node you can find in the DP Kit can solve the situation.

tonyhall007
03-06-2013, 09:07 AM
I did not need to use the DP kit parent plugin. I added a null and placed it in the middle of the ball, then used the parenter option, which is under the add modifier in the motion options to parent the null to the ball, then the target item option works. Going to show my student this way as it works fine. Thanks for the help.

jeric_synergy
03-06-2013, 11:05 AM
So, Parenter correctly received the motion info from Bullet?

lino.grandi
03-06-2013, 11:26 AM
I did not need to use the DP kit parent plugin. I added a null and placed it in the middle of the ball, then used the parenter option, which is under the add modifier in the motion options to parent the null to the ball, then the target item option works. Going to show my student this way as it works fine. Thanks for the help.

Great!

jeric_synergy
03-06-2013, 11:39 AM
I'd like to see a diagram showing how the motion evaluation pipeline works.

RebelHill
03-06-2013, 12:26 PM
I'd like to see a diagram showing how the motion evaluation pipeline works.

Keyframes > MotionModifiers > IK(including SAI, target pole, etc) > AfterIK Modifiers/Channels.

Expressions evaluate after keyframes, so normally between keys/motionMods... however, if some modifer/tool causes keyframes to be laid down during the evaluation series, then expressions will also be evaluated at that point.

Parenter is one of those weirdo modifiers (and there's others) that seem to read motion after IK, even if their after IK box isnt checked. You also can notice with such mods, that get a 5 or 6 instances of them, particularly chained in sequence, and your scene slows down a LOT. I suspect that such mods are forcing a second loop of the evaluation stack to get their info, which causes the behaviour seen here.