Your two lines

GetObjects(kid)
objList += kid

make no sense. The first one calls the recursion but then throws the result away as it is not stored anywhere (objList is a local variable for the function, not a global, and does not exist beyond the context of the current method execution). The second tries to extend a list by a single object instead of another list (the operator += works like extend, not like append) and fails because it cannot iterate through a single object. (Even if you had used the append method or listified kid it would still fail logically because you have already added the kid in the recursion call and then threw it all away.)

What you need to do is extend the local objList by the result list of the recursion call:

objList += GetObjects(kid)

or in context,

import c4d
from c4d import gui

def GetObjects(obj):
      objList = [obj]
      for kid in obj.GetChildren(): 
          objList += GetObjects(kid)
      return objList # should return the parent/selected obejct and all its chidlren

def main():
    test = doc.SearchObject("shoulder_jnt")          
    ikJointChain = GetObjects(test)
    print ikJointChain

if __name__=='__main__':
    main()

Now we are at a point where angels fear to tread...

I can't say what exactly the Start/EndUndo system is doing when not properly used in one level, but it definitely doesn't work in a way that supports nesting. Here I just tried a small modification of my previous scripts:

import c4d

def main():
    doc.StartUndo();
    obj = doc.GetFirstObject();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");

    doc.StartUndo();
    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    doc.EndUndo();

    doc.StartUndo();
    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    doc.EndUndo();

    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");

    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    doc.EndUndo();
    c4d.EventAdd();

if __name__=='__main__':
    main()

I used the same sequence of five renames, but I nested rename 2+3 into a new Start/EndUndo without closing the outer first.
If you apply Ctrl-Z on that, you will find that the first Ctrl-Z reverses the last three renames (NOT just the last 2), one more Ctrl-Z reverses the second rename, and one more the first. That means that an undo step goes back to the last StartUndo (not EndUndo) that the programmer has set. Any nesting is ignored.

I did a few more nesting experiments but I'm not posting them here as they all point to the same behavior. I do not get any errors though, even if I completely botch the sequence - two StartUndo in a row, AddUndo before StartUndo, AddUndo after EndUndo... it actually still works, but with the little limitation that each StartUndo that I issue will break up the sequence and require a new Ctrl-Z to undo. (I am not going into full reverse engineering here now - it would be nice if the documentation could tell us how error cases and nesting are actually handled, though.)

That means that if you have commands that internally perform an Start/EndUndo, you will not be able to get out of the additional Ctrl-Z. Same, I guess, if you issue a StartUndo inside of a function that you wish to reuse (although that may be a problem more suitable for libraries).

You may argue that this is a design flaw. A nested Start/EndUndo could actually be treated like a single subcommand, with a Ctrl-Z working only on the highest level - which would revert the results of a functionality from the view of the outermost Start/EndUndo, while all nested Start/EndUndo pairs on lower levels do not affect the reversal (so you could use a CallCommand including its internal Undos without enforcing another Ctrl-Z in the end). I'm just not sure whether C4D could handle this conceptually, as it would be easy to lose yourself in a tree of Start/EndUndos throughout the program.

Anyway. Your best bet may actually be to skip the CallCommands if possible and perform the necessary change by yourself, so you have a better control over the Undo sequences.
Or you can issue a feature request for a CallCommand with an additional parameter that allows you to suppress the Start/EndUndos that are added internally.

@bentraje I am not using Maya so I can't say anything about that. As a programmer though, I know that there ain't nothing like no free launch... uh, lunch. If Maya is able to undo/redo automatically, then the Python API needs to have that functionality built in (automatic call of something like StartUndo at the beginning, EndUndo at the end, and every API call has an AddUndo integrated. That is possible, yes. You have to pay a price for it though, both in development time (of the API programmers) and in execution time. Maybe that is a good tradeoff; I can't judge that. It's certainly easier for the Python programmer

Personally, I admit that I am a lazy pig and often don't integrate any undo in my scripts. But it is not that difficult as you make it sound right now. You would only have to add an AddUndo at points where you really make a change to the object tree (or related internal data). The actual calculations are unaffected. If you have a really complicated script, it would be best if you create it in layers, with the changes made to the object tree being at as high level in the call hierarchy as possible. This allows for safe exits and controlled error situations. (But we're far off topic now.)

No, you would not need to press Ctrl-Z five times. Look at the following:

import c4d

def main():
    doc.StartUndo();
    obj = doc.GetFirstObject();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    doc.EndUndo();
    c4d.EventAdd();

if __name__=='__main__':
    main()

(warning: If you execute this script you MUST have 5 objects at top level, or the thing will crash.)
Try it, it will rename the objects; one Ctrl-Z is enough to revert all changes.
Now compare this with the following:

import c4d

def main():
    doc.StartUndo();
    obj = doc.GetFirstObject();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    doc.EndUndo();
    doc.StartUndo();
    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    doc.EndUndo();
    doc.StartUndo();
    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    doc.EndUndo();
    doc.StartUndo();
    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    doc.EndUndo();
    doc.StartUndo();
    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    doc.EndUndo();
    c4d.EventAdd();

if __name__=='__main__':
    main()

Here, each AddUndo is encapsulated into a Start/EndUndo block. Now use the script and undo - you will find that each undo only reverts one rename!
So, the Start/EndUndo blocks are the ones that control the "container" that is reverted by Ctrl-Z (as mentioned in my previous post). If you want to revert everything at once, just encapsule the whole execution of the script in the main() function with a Start/EndUndo block. It is not necessary to repeat this block with every method you write.

Now have a look at the following:

import c4d

def main():
    doc.StartUndo();
    obj = doc.GetFirstObject();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    obj = obj.GetNext();
    doc.AddUndo(c4d.UNDOTYPE_CHANGE_SMALL, obj);
    obj.SetName("Renamed!");
    doc.EndUndo();
    obj = obj.GetNext();
    obj.SetName("Renamed!");
    obj = obj.GetNext();
    obj.SetName("Renamed!");
    c4d.EventAdd();

if __name__=='__main__':
    main()

Execute and undo... Ooops! Only three renames were reverted! As obvious from the script, two renames are outside of the Start/EndUndo block and have no AddUndo either, so Ctrl-Z will not affect these.

I leave further exploration to you, but I fear you will not get a super simple undo automation as in Maya.

@bentraje Nope. Only the Start/EndUndo containers determine how often you need to hit Ctrl-Z. Not the AddUndos that you issue in between, or the type of these AddUndos. Look at the following:

import c4d

def main():
    doc.StartUndo()
    cube = c4d.BaseObject(c4d.Ocube)
    doc.InsertObject(cube, None, None)
    doc.AddUndo(c4d.UNDOTYPE_NEW, cube)
    sphere = c4d.BaseObject(c4d.Osphere)
    doc.InsertObject(sphere, cube, None)
    doc.AddUndo(c4d.UNDOTYPE_NEW, sphere)
    plat = c4d.BaseObject(c4d.Oplatonic)
    doc.InsertObject(plat, None, sphere)
    doc.AddUndo(c4d.UNDOTYPE_NEW, plat)
    doc.EndUndo()
    c4d.EventAdd()

if __name__=='__main__':
    main()

This code creates a hierarchy of three objects, each with their own AddUndo but all in the same Start/EndUndo block. That means all three objects will be removed at one single Ctrl-Z. Try it.

Also, if you cut out the generation of the objects and put it into a method, this will change nothing, it will just make the Start/EndUndo bracket in your code more visible:

import c4d

def create():
    cube = c4d.BaseObject(c4d.Ocube)
    doc.InsertObject(cube, None, None)
    doc.AddUndo(c4d.UNDOTYPE_NEW, cube)
    sphere = c4d.BaseObject(c4d.Osphere)
    doc.InsertObject(sphere, cube, None)
    doc.AddUndo(c4d.UNDOTYPE_NEW, sphere)
    plat = c4d.BaseObject(c4d.Oplatonic)
    doc.InsertObject(plat, None, sphere)
    doc.AddUndo(c4d.UNDOTYPE_NEW, plat)
        
def main():
    doc.StartUndo()
    create()
    doc.EndUndo()
    c4d.EventAdd()

if __name__=='__main__':
    main()

So you can just do that and put the Start/EndUndo bracket in the top call, and then work your way through your code by only using the proper AddUndos.

Now you will ask, why the different undo types? This helps C4D to determine the extent of change that will be done (mostly, AddUndo comes before the change...), and therefore minimize the amount of data stored in the undo list. For example, if you only change a flag on a polygon object with 100 000 polys, then it would be an excessive waste to store the full object in the undo list. It's quite sufficient to store the BaseContainer, or even a single value from that container, to revert and redo the change. (Keep in mind that you don't just want to undo but at times also to redo an undone operation.)

If you know what the AddUndo really stores for future Undos and Redos, you can save yourself some AddUndos. Try the following code:

import c4d

def create():
    cube = c4d.BaseObject(c4d.Ocube)
    doc.InsertObject(cube, None, None)
    doc.AddUndo(c4d.UNDOTYPE_NEW, cube)
    sphere = c4d.BaseObject(c4d.Osphere)
    doc.InsertObject(sphere, cube, None)
    plat = c4d.BaseObject(c4d.Oplatonic)
    doc.InsertObject(plat, None, sphere)
        
def main():
    doc.StartUndo()
    create()
    doc.EndUndo()
    c4d.EventAdd()

if __name__=='__main__':
    main()

There is only one AddUndo while three objects are generated. But since the two other new objects are linked as children of the first new object, the whole substructure will behave as one - if you undo, you will still see all three objects disappear, and - more important! - if you redo, all three will appear again!

Now, I have no access to the C4D undo code, but obviously the undo cuts the new object from the hierarchy including everything that is attached to it, and keeps the structure intact for a later redo.

If you had linked one of the child objects somewhere else, you would need an additional AddUndo for it, naturally. E.g. if you create the Platonic as top level object, it would no longer be affected by the Undo of a parent object.

@bentraje The Python tag must be evaluated in every redraw of the scene (not just on every frame but far more often; try this by insert a Print in the code...) because it may not just depend on variables but on values from the scene (e.g. "if the object X is placed farther away than 1000 units then move object Y to..."). Keeping track of original values and comparing them with current values like this is nigh impossible (requiring analysis of code semantics), so the tag will be simply re-evaluated whenever encountered.

You can insert an "early exit" in the tag, of course, by testing for changed variables yourself (as you as programmer have more information on the semantics than the Python interpreter/compiler). But you will need to store the values to compare with somewhere, and you will need to take into account that the execution may not happen in frame sequence (e.g. when the user scrubs the timeline backwards).

As for the original question, I tend to put calculations into Python nodes inside the XPresso because plain math calc creates TONS of XPresso nodes that tend to become very confusing. On the other side I keep XPresso nodes whenever I want to see the affected objects in the circuit directly, or when I need a GUI for adapting something (e.g. Range Mapper with spline interface), or when the node does complicated things that I don't want to reprogram in Python (Hair intersection? ... nah, never used that ). When the whole thing is easier to maintain as a Python tag in the end, I put it into the tag...

So it's not so much a question of whether the execution is faster, it's pure convenience of the result for me.

You are probably in need of GetModelingAxis() which reacts to object selections or polygon/edge/point selections.

Here's how I determine the pivot for CollieMouse, which is supposed to be the same pivot that the built-in transformation functionality is using:

	BaseObject* objcenter = doc->GetRealActiveObject(nullptr, nullptr); // GetActiveObject() fails with multiple selections?
	if (objcenter != nullptr)
	{
		Matrix centermat = objcenter->GetModelingAxis(doc);
		pivot = centermat.off;
	}

Note: This is R19 C++, but I can see GetModelingAxis in R20 Python as well.

If this is not what you're looking for, you can take a point as vector, transform this vector by the object's world matrix, and get the world "matrix" for the point. If you need more than one point, use the average of those points.

Actually, Python works differently from C++. A "global" variable there is only global for the current execution context. In Python, variables are not declared; Python creates them when they are first used ("first" meaning, there is no such variable in the current execution context already).

Where a C++ global variable is created at compile time and represents one location in memory throughout, Python globals are created at runtime in their context. Cinema 4D has one context per Python element, so if you are accustomed to C++ globals, the following will irritate you:

• Create two objects with a Python tag
• Write the following code into the tags:

import c4d

def main():
    global x

    if doc.GetTime().GetFrame(doc.GetFps()) == 0:
        x = 1
        print "Tag 0 x set to 1"
    else:
        print "Tag 0 x = ", x
        x += 1

for one tag, and

import c4d

def main():
    global x

    if doc.GetTime().GetFrame(doc.GetFps()) == 0:
        x = 0.5
        print "Tag 1 x set to 1/2"
    else:
        print "Tag 1 x = ", x
        x += 1

for the other. Obviously, the first tag counts on full integers and the second on halfs, both are reset on frame 0.

The output amounts to

Tag 0 x set to 1
Tag 1 x set to 1/2
Tag 0 x =  1
Tag 1 x =  0.5
Tag 0 x =  2
Tag 1 x =  1.5
Tag 0 x =  3
Tag 1 x =  2.5
Tag 0 x =  4
Tag 1 x =  3.5
Tag 0 x =  5
Tag 1 x =  4.5
Tag 0 x =  6
Tag 1 x =  5.5
Tag 0 x =  7
Tag 1 x =  6.5
Tag 0 x =  8
Tag 1 x =  7.5
Tag 0 x =  9
Tag 1 x =  8.5
Tag 0 x =  10
Tag 1 x =  9.5

Obviously, although both tags claim a global x, they access different x's. That's because their contexts are different. Which also means that they cannot exchange data through globals this way. (You can try with an external module that you import, but I don't have time to verify that at the moment.)

If all you want is to store a value between executions of a tag, this is easy to implement this way. However:

• You must make sure that Python creates the variable at some point. Here, I did that through a first value setting at frame 0. Which also means that every time the timeline passes through 0, the value is reset.
• You must pay attention to the evaluation of the object tree. I chose a tag here since the tag is evaluated with the tree every time. That is NOT the case for a generator, as there are caching mechanisms at work.
• You must take care of situations like "jumping around in the timeline", replaying backwards, setting the time explicitly through some other plugin, and such.

Since the OP has asked explicitly for scripts, I would like to add: @m_adam 's "Global" method will not work for scripts, as their Python scope is (apparently) only valid for the current execution. It does work for Python tags and XPresso Python nodes where the scope seems to exist for the lifetime of the tag.

If you work with tags/nodes and have actual variables to store in the globals, you need to account for the timing and the frequency of execution (e.g. do not rely that the next execution is actually the next frame). This will not apply for one-time executions like an initialization, but even there you may want to determine an anchor point (e.g. at frame 0) where the value is reset or calculated for the first time.

@bentraje Meh, I just noticed my first code is not a good example because of what I later wrote. Since the top object of the created hierarchy is already determining the fate of the subobjects, the additional AddUndos have no true function. That does not make it wrong but it does not properly prove what I claim

Try the following:

import c4d

def create():
    cube = c4d.BaseObject(c4d.Ocube)
    doc.InsertObject(cube, None, None)
    doc.AddUndo(c4d.UNDOTYPE_NEW, cube)
    sphere = c4d.BaseObject(c4d.Osphere)
    doc.InsertObject(sphere, None, None)
    doc.AddUndo(c4d.UNDOTYPE_NEW, sphere)
    plat = c4d.BaseObject(c4d.Oplatonic)
    doc.InsertObject(plat, None, None)
    doc.AddUndo(c4d.UNDOTYPE_NEW, plat)
        
def main():
    doc.StartUndo()
    create()
    doc.EndUndo()
    c4d.EventAdd()

if __name__=='__main__':
    main()

Here, the three objects are created independently on top level, yet still all disappear with one CTRL-Z.

(And again, this is true for all types of AddUndo.)

@bentraje Yeah, the second part was meant just in case you have need for a manual process. GetModelingAxis() takes multiselections of elements into account.
However, I believe GetModelingAxis() works by selected mode (as you can have different selections for points, polys, and edges in parallel depending on whether the point, poly, edge, or object mode is active. So if you explicitly need the point selection and use the method in a script, you may want to switch to the point mode before using GetModelingAxis(). (Also, the actual modeling axis can be changed by the tools, so caution is in order. Personally, this is the behavior I needed, so I didn't make any big experiments.)

In general, yes, this is a real consideration in numeric calculations when you work with limited-size floating point numbers. Cinema 4D even takes precautions against that in case of time values, which are internally described as rationals with numerator and denominator. (Maybe other places, I don't know the source code.)

Whether the calculations are affected "visibly" (either in the numeric fields which show, however, only three digits after the point, or in the viewport) is a question only you can answer.

To mitigate, you e.g. avoid certain calculations (very large and very small numbers in one calculation are generally bad), or you compare against an epsilon tolerance around the target value, or you use modulos to put numbers into a grid, whatever is most fitting for the specific situation. (Cinema 4D has an epsilon comparison function somewhere.) You can find the necessary techniques on the web; they are not unique for C4D of course.

However - in praxis, I only care for a certain subset of situations that I deem likely to cause issues. A complete numeric analysis of your algorithms is generally too much effort; most cases will just lead to an invisible imprecision in an object's or a point's position and can be disregarded. That's not an excuse to drop these considerations altogether; use reasonable caution.

@mocoloco said in 3D Mouse Slider Focus:

Thanks a lot @cairyn for your answer. Yes, that's a super old thread, but it's the one talking about CollieMouse
Do you have a link to get / buy it? The only link I found is about a v1.2 free, which is not working under R23.

I do have a R23 version. You may want to contact me under
cairyn at tigress dot com
to continue the talk; I guess this is not appropriate for this forum. Thanks!

You are mixing up polygon and polygon object interchangeably in your posts, so I'm not sure what you mean by "obtain a polygon corresponding to a selection". Assuming you mean exactly the stuff you're showing in the screenshots, you can use the high-level functionality instead of going poly by poly: take the selection tag, select the polys within, split off the selection with the fitting SendModelingCommand. You may need to delete the polys from the original, too.
This is most likely faster than handling all polys in Python, as SendModelingCommand will execute the functionality in the native C++ code.

just as a tip, you seem to miss a basic technique to find out parameters.
Open the Python console. Select the label of the desired parameter in the attribute manager. Drag the label into the console. The colsole will react by showing you the parameter access, e.g.:

Material[c4d.TEXTURETAG_RESTRICTION]
'MySel'

Press Return to get the current value, which in this case is MySel.
You can now use the square bracket notation on your object (texture tag).

@eziopan said in [Python] Get and Set Move Tool's XYZ Axis Lock State:

Thanks @cairyn! When i read c4d.IsCommandChecked(id), it says Forbidden to call in expressions (Python generator, tag, XPresso node, etc.). Is it safe to use this in a Interaction Tag?

That is an interesting question; I guess the Maxon people will know for sure. The tags mentioned are all called during an evaluation of the object tree, which is a threaded operation, which forbids certain operations. The interaction tag responds to user interaction, which IMHO is different? If the script in an interaction tag is called in the main thread, you could use these commands as well.

I just tried and used IsCommandChecked and CallCommand in an interaction tag in the mouseDown() callback, and it seems to work; at least C4D didn't crash. That's no guarantee that it will never crash, of course, so I defer to Maxon specialists in the matter

As far as the Select/Highlight issue goes, I find myself unable to trigger the onHighlight callback properly. The help says "This is called when the object is highlighted by the mouse cursor." but no, it isn't. When I click the right mouse button over the object and drag it so the menu doesn't appear, I get the onHighlight console printout after releasing, but only in Model Mode so far. This is a fairly mysterious message. ("Highlight Object" needs to be checked; but even so - I don't see any highlight...)

The status-test equivalent to CallCommand(12153) is c4d.IsCommandChecked(12153) etc.

A SelectionTag (no matter what type the selection is) has a method GetBaseSelect which returns a (reference to the contained) c4d.BaseSelect object which in turn contains the needed functions:
https://developers.maxon.net/docs/Cinema4DPythonSDK/html/modules/c4d/BaseSelect/index.html

(You may want to have an eye on the API description which can answer these easy questions without the need to write an elaborate question )

@mari said in Buttons do not work when opening dialog with "DLG_TYPE_ASYNC":

Is there a window in which you can create a program?

Just in case you really mean an editor window: no. The Script Manager handles pure scripts that reside in the script directory, which is different from the plugin directory (but you found that out already). While the Script Manager theoretically handles any text, it would be quite awkward to write plugins with it.

Personally, I am using an external editor to write plugins in Python. You can use any editor or Python IDE, but make sure to store the results as Unicode UTF-8 (or use the Python notation for a different encoding). While you are changing the source code, you can reload the plugin with Cinema's "Reload Python Plugins" functionality to see the changes without restarting Cinema altogether.

It is a good idea to start with a very simple plugin which loads correctly and then expand from there. If the plugin has certain errors, it may fail during loading and not appear in Cinema's plugin list. In that case, it will not be loaded by "Reload Python Plugins" even after you externally corrected it, as that function apparently only affects plugins that are already there.

I think there is a manual for connecting an IDE for debugging with Cinema somewhere here on this forum.

You cannot call an asynchronous dialog from a script.

When your dialog is asynchronous, then the Open function returns immediately. The main() function returns. Then the script ends. The class MyDialogs will essentially be gone. This leaves the dialog window without a script to handle it.

If you need an asynchronous dialog, you may want to program a CommandData plugin instead of a script.

@mocoloco Yes, CollieMouse works under R23 (it's the first thing I update since it's a primary tool for me, except that I kinda skipped R20).

Hey, this is a super old thread...