Modify rotation of clone child objects

[will_blizzard]

Hi there,

Sorry if this has been asked and answered before, but I've been searching in vain for days for a solution and can't figure it out.

I'm trying to write a python effector which will mimic the target effector, but which will allow me to separate specifically the heading and pitch onto two separate child objects of a clone.

The use case is to be able to clone 3D models of moving lights (where the arm assembly rotates( heading) and has a rotating (pitch) head attached to it) and use a target effector-like system to have the models follow a null. The clones are set up as follows:

Null Parent (The fixture root)
---Fixture base geometry (this is the part of the fixture that doesn't move)
---Null (The fixture arms, should react to heading)
---Arm geometry
---Null (The fixture head, should react to pitch)
---Head geometry and light

I've tried every iteration of constraint and protection tags I can think of, and also have a python effector which modifies ALL of the clones children to follow the target, but does not modify each individual clone's children individually (as the target effector would).

The python effector script I've written is below:

from typing import Union
import c4d
from c4d.modules import mograph as mo
from c4d import utils

op: c4d.BaseObject # The python effector

gen: c4d.BaseObject # The MoGraph Generator executing the effector
doc: c4d.documents.BaseDocument # The document evaluating this effector
thread: c4d.threading.BaseThread # The thread executing this effector


def SetTarget (objMx, target):
    pos2 = target[c4d.ID_BASEOBJECT_REL_POSITION]
    pos1 = objMx.off
    vec3=(pos2-pos1).GetNormalized()
    vec2=vec3.Cross(c4d.Vector(0,1,0)).GetNormalized()
    vec1=vec3.Cross(c4d.Vector(1,0,0)).GetNormalized()
    newMx = c4d.Matrix(pos1,vec1,vec2,vec3)
    newRot = c4d.utils.MatrixToHPB(newMx)
    # print(newRot)
    #obj.SetMl(new_mx)
    return newRot

def main() -> Union[c4d.Vector, float, int]:
    
    target = doc.SearchObject("TargetNull")
    if (target == None): return False

    moData = mo.GeGetMoData(op)
    gen = moData.GetGenerator()
    cnt = moData.GetCount()
    cntArray = moData.GetArrayCount()
    marr = moData.GetArray(c4d.MODATA_MATRIX)
    clarr = moData.GetArray(c4d.MODATA_CLONE)
    fixt = gen.GetDown()
    base = fixt.GetDown()
    yoke = base.GetDown()
    head = yoke.GetDown()

    for i in range(cnt):
        newRot = SetTarget(marr[i], target)
        head.SetRelRot(c4d.Vector(0,newRot.y,0))
        yoke.SetRelRot(c4d.Vector(newRot.x,0,0))

    #moData.SetArray(c4d.MODATA_MATRIX, marr, False)
    c4d.EventAdd()
    return True

I can provide the c4d file as well if necessary, but hopefully what i've noted above makes sense.

Thanks in advance for the help.
Will

[Manuel]

hi,

First, we have a bug with the python effector, it is not working when you render to pictures viewer.

If i correctly understood the question:
i don't think this is doable with one single cloner. The clones cannot have different rotation for a child object. Otherwise, they would not be clone anymore.

One solution that come to my mind would be to use two cloners, one for the arm, the other for the head. Using an Inherit effector, the head could inherit from the rotation of the arm, and you would be free to add another effector to this head to add rotation.

lights.c4d

But that will not solve the problem if you want to follow a target or different targets. The solution also depend on what are exactly your needs. In this forum we try to focus on programming questions, you are a step before that.

Cheers,
Manuel

[will_blizzard]

@m_magalhaes

Hi there,

Well, I figured it out, and have no issue rendering to picture viewer with python effector, so not sure what you're referring to, but maybe the bug is fixed?

Here is the code that works as intended, although it requires a frame update to change. I'm guessing I can fix that as well with a bit more tinkering. This works as intended with the cloner in either instance or render instance mode.

from typing import Union
import c4d
from c4d.modules import mograph as mo
from c4d import utils

op: c4d.BaseObject # The python effector

gen: c4d.BaseObject # The MoGraph Generator executing the effector
doc: c4d.documents.BaseDocument # The document evaluating this effector
thread: c4d.threading.BaseThread # The thread executing this effector


def SetTarget (objMx, target):
    pos2 = target[c4d.ID_BASEOBJECT_REL_POSITION]
    pos1 = objMx.off

    vec3=(pos2-pos1).GetNormalized()
    vec2=vec3.Cross(c4d.Vector(0,1,0)).GetNormalized()
    vec1=vec3.Cross(c4d.Vector(1,0,0)).GetNormalized()
    newMx = c4d.Matrix(pos1,vec1,vec2,vec3)
    newRot = c4d.utils.MatrixToHPB(newMx)
    return newRot

def main() -> Union[c4d.Vector, float, int]:
    # Called when the effector is executed to set MoGraph data.
    target = doc.SearchObject("TargetNull")
    if (target == None): return False

    moData = c4d.modules.mograph.GeGetMoData(gen)
    marr = moData.GetArray(c4d.MODATA_MATRIX)

    cloneSource = gen.GetCache().GetDown()
    clones = []

    while cloneSource != None:
        clones.append(cloneSource)
        cloneSource = cloneSource.GetNext()

    cnt = len(clones)

    frame = doc.GetTime().GetFrame(doc.GetFps())
    for i in range(cnt):
        fixt = clones[i]
        base = fixt.GetDown()
        yoke = base.GetDown()
        head = yoke.GetDown()

        newRot = SetTarget(marr[i], target)
        head.SetRelRot(c4d.Vector(0,newRot.y,0))
        yoke.SetRelRot(c4d.Vector(newRot.x,0,0))

    moData.SetArray(c4d.MODATA_MATRIX, marr, False)
    c4d.EventAdd()
    return True

[Cairyn]

@will_blizzard said in Modify rotation of clone child objects:

have no issue rendering to picture viewer with python effector, so not sure what you're referring to

The error is in the function moData.GetFalloffs(), which you are not using, so you are not affected I guess.

[m_adam]

Hello @will_blizzard,

without further questions or postings, we will consider this topic as solved by Wednesday 31/05/2023 and flag it accordingly.

Thank you for your understanding,
Maxime.