I want to create a lookAt controller for rotation (Y Axis only). I just modified a code from Here:
delete Objects
Obj = teapot()
Target = box pos:[100,0,100]
completeredraw()
dir = normalize (Target.Pos - Obj.Pos)
vec = normalize Obj.transform[3]
tm = Obj.transform
rtm = angleaxis (acos (dot vec dir)) (normalize (cross dir vec))
Obj.transform = translate (rotate (scalematrix tm.scale) (tm.rotation*rtm)) tm.pos
This code works perfect for me, but I get some error when I use it in script controller.
first of all why the built-in LookAt controller doesn’t work for you?
another question: where do you want to use expression? rotation controller or transform controller?
(
delete objects
point name:#s axis:on wirecolor:green
point name:#t pos:[20,0,0] axis:off wirecolor:yellow
ss = $s.rotation.controller = createinstance rotation_script
ss.addobject "pos" $s.position.controller
ss.addnode "target" $t
ex = "tm = arbaxis (normalize (pos.value - target.pos))
"
ex += "prerotateX tm -90
"
ex += "tm.rotation"
ss.setexpression ex
)
as added controls to script controller you can use position subanims if you want.
also you can build angleaxis (as quaternion value) instead of transform with using it’s rotation part (as i do in the example)
The Obj will be flipped when I move Target in negative X axis, just test it with teapot and you see the problem. Another note is that I need rotation in single Y axis.
of course it flips. because i do nothing for two other axis.
if you need to animate y-rotation make rotation controller as a list with lookat and free eulerXYZ
doesn’t work either. I founded another code from you in other post, and this is my ugly version with some modification:
fn YLookAt Obj Target =
(
Orient_Script = rotation_Script()
Orient_Script.AddNode "Target" target
Orient_Script.AddNode "Obj" Obj
St = ""
St+="if Target != undefined then
"
St+="(
"
St+="if (Parent = Obj.Parent) == undefined
"
St+="then
"
St+="v = normalize (Target.pos*(inverse (translate (matrix3 1) Obj.pos)))
"
St+="else
"
St+="v = Target.pos*(inverse (translate (Parent.transform.rotation as matrix3) Obj.pos))
"
St+="ang = atan (v.z/v.x)
"
St+="if Obj.Scale.X < 0 then Fac = -1 else Fac = 1
"
St+="ang += if v.x < 0 then Fac*90 else Fac*-90
"
St+="((rotateYMatrix -ang) as quat)
"
St+=")
"
St+="else (quat 0 0 0 1)"
Orient_Script.SetExpression St
Obj.rotation.controller = Orient_Script
)
This code is near to what I want but, has problem when I scale the Obj.
as i guess you have a pair of objects: normal and flipped (scaled with a negative value).
and you want them both look at specific node using Y axis as a direction.
true?
if i guess wrong please show a picture how ‘lookAt’ has to look like for normal and negative scaled cases.
I wanna use it for rigging 2d (cutout) character. this means character parts will rotate only in one axis. in this kind of rigging flipping every part is necessary. Please see 3 attached image.
it looks like you over-complicate the rig solution.
you can simply solve it using hierarchy only:
upperArm_bone->lowerArm_bone->hand_bone
and
upperArm_bone->upperArm_flesh
lowerArm_bone->lowerArm_flesh
hand_bone->hand_flesh
delete objects
(
b0 = BoneSys.createBone [0,0,0] [20,0,0] y_axis
b0.name = "UpperArm_bone"
b1 = BoneSys.createBone [20,0,0] [40,0,0] y_axis
b1.parent = b0
b1.name = "LowerArm_bone"
b2 = BoneSys.createBone [40,0,0] [50,0,0] y_axis
b2.parent = b1
b2.name = "Hand_bone"
f0 = point name:"UpperArm_flesh" transform:b0.transform parent:b0
f1 = point name:"LowerArm_flesh" transform:b1.transform parent:b1
f2 = point name:"Hand_flesh" transform:b2.transform parent:b2
)
bone system gives you true lookAt constraining, and ‘flesh’ controls are free to have own animation. you can lock all axis to preserve their change
It’s already complicated with IKFK,Skin,Flipping,Moving separately,…
However, I will tell you some problems of your rig:
[ol]
[li]Every mesh is skinned to two bones (pluse one twist bone, orientation constrained to this two bones) and must be flipped locally, How you flip UpperArm bone in X axis while lower part of the mesh is directed to the hand?[/li][li]How I can move just ForeArm in Z axis, but hand stay in it’s position?[/li][/ol]
To see what final rig looks like, please take a look at attached max file. it would be great if you tell me how I can optimized it. Note that to Flip or move in Z, use the shapes with name “*IKFKP”(Red NGones).