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Why is this crazy stuff happening? (expressions + parenting nonsense…)
Okay, I made a forward kinematics character, and to keep it simple it lets just ignore the other limbs and it goes:
Body <- Thigh <-Calf <-Foot... Now I have a solid layer with a BEAM effect on it and the idea was to make a BEAM going from the Foot of the character to another point. So I put this expression on the "Starting Point" of the beam: thisComp.layer("FOOT").transform.position Thinking, logically, that the beam would go to the position of the FOOT and follow it. Oh how wrong I was...it goes far away, way off the mark. I tried some other additions to the expression to make it work but I think I'm critically missing something here.
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3 Replies
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The trick with parenting is that the parented object gets its own local coordinate system. This is good since it lets you, for instance, animate rotations indpendently of what the parent object is doing. The downside is that you have to translate those local coordinates to global ones if you want to tell an expression where things actually are.
See, for instance, here:
– Alon
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The magic word is layer space transforms. As alon_a says, you need to add this to your expressions. In your example it could be something like that:
foot=thisComp.layer(“Foot”);
foot_point=foot.toWorld(foot.anchorPoint);[foot_point]
Mylenium
[Pour Myl
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Amazing, I think I understand now. Thank you.
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