how to extract normal from sub-object and apply to another object's rotation?

[josh3light]

for everyone's reference, I'll post part of the solution as I found it
I pieced this together with resources from this forum
thanks everyone

I used this on a rotation script controller on $point01 with sphere01= $sphere01 and pnt = $point01 as node variables


fn getrot a which_axis b =
(
local c = normalize (b - a)
local angle = acos (dot which_axis c)
local axis = normalize (cross which_axis c)

local out = (angleaxis angle axis) as quat
out
)
pa= getvert sphere01 209
pb= getvert sphere01 210
pc= getvert sphere01 241
pd= getvert sphere01 242

vAB=pB-pA
vAC=pC-pA
vCD=pD-pC

vectnorm= (cross vAB vAC)

a = vectnorm
b = pnt.position
q = getrot a z_axis b
inverse q

[josh3light]

This is still not ideal as there is some odd flipping happening

basically, what I REALLY want to do is just stick a helper object on a mesh and have it really stick there, position and rotation, without parenting it to the main object

so I can spin and move and deform the main object and that helper just sticks there

any ideas?

[josh3light]

just for the record, I'm now using the cloth modifier to solve the problem. It's a bit inefficient for just attaching one object to another, but since I'm rigging wing feathers it has the added benefit of giving them secondary movement with the simulation.

I'd still like to know how to do it with script to have full control over it though

[Bobo]

This is still not ideal as there is some odd flipping happening

basically, what I REALLY want to do is just stick a helper object on a mesh and have it really stick there, position and rotation, without parenting it to the main object

so I can spin and move and deform the main object and that helper just sticks there

any ideas?

An Attachment controller does not do the job?

[josh3light]

Thank you very much Bobo, I have used the attachment constraint only once before and I totally forgot about it. It will work very well in this case. I have been watching your advanced maxscript dvd lately so I guess I was thinking in an overly complicated way. :)

[_stev_]

Have you tried using "getNormal" or "getFaceNormal"?

[Bobo]

Thank you very much Bobo, I have used the attachment constraint only once before and I totally forgot about it. It will work very well in this case. I have been watching your advanced maxscript dvd lately so I guess I was thinking in an overly complicated way. :)

Yep, my bad! ;)
Btw, the DVD mentions the Attachment constraint in the Barycentric coordinates topics...

[josh3light]

_stev_, I will try the getFaceNormal command soon as well.

now that the workflow issue is solved I have a lot of work to do, over 20 wings need to be animated by tomorrow :)

I've watched about half of your Advanced DVD Bobo and I need to watch it again before I watch the other half... there's so much in there

Thanks everyone!

[CGTalk Moderation]

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.