Make editable an object generated by GetVirtualObjects()

ferdinand

Hi,

I am absolutely fine with it if you prefer something else.
I do not know what you are doing exactly in your video, but yes, "your" side does look better. But that almost has certainly nothing todo how you impement your GVO.
I have to point out again that there is no my method and your method. You are using GVO in a way that is not allowed by the c4d SDK. Read the provided links above on threading. They are crystal clear on that topic. Or contact the the SDK support team, they will tell you the same.
While things might work in your small test environment, they won't in a production environment. Consider how pissed your clients or your company will be when your plugin has corrupted their files.

Consider yourself to have been warned

Cheers
zipit

mfersaoui

@zipit
Hi,
Sorry, I said "My method" and "Your method" just to differentiate between the two methods. I don't said that my method is better I'm just searching a legal method that allow me to obtain a similar result as the method that I'm using now.
in the method that I'm using the preset is loaded in document only one time. So, for example when I move the object handle points the change is applied into the previous loaded object.

The loaded object has a python tag that contain all object controls.
here is an example of python tag content:

import c4d

def main():
    obj = op.GetObject()
    parent = obj.GetUp()
    scale = parent[c4d.PRIMITIVEOBJECTS_GLOBAL_SCALE]
    
    # Objects scale
    obj.SetAbsScale(c4d.Vector(scale))

But with second method at each change the preset object is reloaded from disc or cache with the new changes (the preset object is removed then reloaded with the new changes) and that result that the object is becomes not visible in the View during a few thousandths of a second.

I'm thinking about another alternative, is the following code cause the same problem:

def GetVirtualObjects(self, op, hierarchyhelp):
        doc = documents.GetActiveDocument()

        path = os.path.join(os.path.dirname(__file__), "res", "my_scene.c4d")
        load = c4d.documents.MergeDocument(doc, path, c4d.SCENEFILTER_OBJECTS)
        if load is False:
            return True
        
        return c4d.BaseObject(c4d.Onull)

ferdinand

Hi,

no need to be sorry, I am / was not offended. I was just trying to be very clear about the implications of your approach.

If you want to have a statically generated object, ObjectData is not the correct base class for you, as its whole purpose is to provide a dynamically generated object when you overwrite GVO.
Loading an object from a preset file is quite an unusal thing to do for the ObjectData type. The more common thing to do, would be to construct your rig procedurally within your GVO. Which would probably also (apart from performance benefits) alleviate the problems you have shown in the video.
Also noteworthy is, that a python scripting tag also calls the draw() function of your script, which you could use to draw / react to to handles with your original xpresso and user data steup.

Cheers
zipit

mfersaoui

@zipit
Hi,
Thank you, I'm trying to rebuild all my rig inside the GVO and I think I will using C++.
is it better to use c++?

Cheers
Mustapha

ferdinand

Hi,

@mfersaoui said:

is it better to use c++?

I think the answer to that is highly subjective. Both SDKs and languages have their strengths. As your plugin probably is neither going to be computationally expensive, nor will be in need of any of the more advanced features only the C++ SDK does offer, I would say, Python wins this cost/gain comparison by a long shot.

But that is subjective

Cheers
zipit

s_bach

Hello,

just to make some things clear:

The purpose of GetVirtualObjects() is to fill a cache with virtual objects.
It is NOT the purpose of GetVirtualObjects() to modify the document / the scene graph.
It is forbidden to edit the scene graph from within the scene execution pipeline e.g. from within GetVirtualObjects().
One must only edit the scene graph in reaction to some user interaction e.g. after the user pressed some button in the UI or used a tool.
One must never call GetActiveDocument() in a NodeData based function. The active document is the document currently displayed in the viewport; but there is no reason to think that this is the document that hosts the object.
Consequentially, one must never call EventAdd() in a NodeData based function; especially not from within the execution pipeline.
If you want your generator to load a given scene file, you can load that scene with LoadDocument() and just COPY the content into the cache.
The Python API is an incomplete wrapper around the C++ API. So some functions may be missing in the Python API.

best wishes,
Sebastian

mfersaoui

@s_bach said in Make editable an object generated by GetVirtualObjects():

GetVirtualObjects()

Hello,
Thank you, I decided to use C++ to do that, I just post new topic "MAXPORTS GraphView Flags - Description Resource" is a continuity of this topic.

mfersaoui

@s_bach said in Make editable an object generated by GetVirtualObjects():

LoadDocument()

Hello,
I gave up the idea to merge objects from scene file, I had generate my object and all her sub-objects inside the GetVirtualObjects(). But now I'm searching how to assign materials to my sub-objects, I would imagine that is the same as objects, should I use the LoadDocument()? if yes are there examples? and then can I change these materials proprieties from the object description resource or I must to use CommandData dialog?
Thank you.

s_bach

Hello,

a generator (GetVirtualObjects()) cannot create materials. You must generate materials in reaction to user-interaction (Material Manual). Then you can assign materials to your (virtual) objects using a TextureTag (TextureTag Manual).

for example, you could detect when your generator object is created from the UI by listening to the MSG_MENUPREPARE message in NodeData.Message(). Then you can create all the materials you want to use later.

best wishes,
Sebastian

mfersaoui

@s_bach
Hello,
Thank you, As you explained, I create all materials in NodeData.Message() and then I called them in the GVO. I just want to know if is it allowed to edit the called material parameters inside the GVO or not? see example bellow:

BaseObject* MyObject::GetVirtualObjects(BaseObject* op, HierarchyHelp* hh) {
        ...
        BaseObject* container = BaseObject::Alloc(Onull);
	if (!container)
		return BaseObject::Alloc(Onull);

	container->SetName("Container");

	BaseMaterial* material = doc->SearchMaterial("my_material");
	if (material) {
		// create the texture tag
		TextureTag* const textureTag = static_cast<TextureTag*>(container->MakeTag(Ttexture));
		if (textureTag == nullptr)
			return maxon::OutOfMemoryError(MAXON_SOURCE_LOCATION);

		const Float Brightness = data->GetFloat(MYOBJECT_LIGHT_INTENSITY);
		
		// Is the following action allowed inside GVO:
		material->SetParameter(DescID(MATERIAL_LUMINANCE_BRIGHTNESS), Brightness, DESCFLAGS_SET_0);

		textureTag->SetMaterial(material);
	}
        ...
}

Best,
Mustapha

mfersaoui

I think this is not allowed. I've just seen the list of the Forbidden Functions and "Make any changes to materials." is inside.

s_bach

Hello,

as said before, it is not the purpose of GetVirtualObject() to edit the scene or to edit elements of the scene; this includes materials.