@m_magalhaes
Thank you for a quick reply!
I'm sorry, I made an idiotic mistake. I simply didn't add
the following piece of code:

case C4DPL_INIT_SYS:
	{
		// load resources defined in the the optional "res" folder
		if (!g_resource.Init())
			return false;

		return true;
	}

in the main.cpp

Thanks, again.
I hope my next questions will have more sense.
It should be an architecture plugin in the end :)
Yaroslav.

Dear c4d fellows,
Long ago I wrote a simple plugin for cinema4d in python.
I didn't know how to code python back then, and learned it while writing the plugin.
So I didn't even know how to debug the .pyp file in debugging mode.
Now I decided to improve it. The question is: how to set up a debugging mode (the analogue of visual studio for c4d but for python). Is it possible? (I mean going line by line through pyp file and see the values of local variables in console)

Yaroslav.

Ferdinand,
that indeed helps a lot!
The points are indeed too many ))
I may imagine how... well, "unsofisticated" my piece of code looks.
Thank you for going so far in the explanation!

Yaroslav.

@ferdinand

Thank you Ferdinand for explaining everything!

Currently, I decided to temper with the normals of my polygon object to make smoothing by hand.
However, what I noticed, is the following:

Suppose I don't create normal tag and simply create a phong tag for my polyobject.
Unfortunately, despite appearing in the menu of the object, somehow it doesn't work (despite my changing the phong angle in the menu).

At the moment I created a function which simulates the extrude functionality (for the reasons of plugin, I refrain from using the built in c4d extrude function )

I feed it with initial closed spline, the extrude height and precision (The way I interpolate curved elements of the spline with line elements)

void wall(BaseDocument* document, SplineObject* spline, double height, double precision) {
	LineObject* spline_linear = spline->GetLineObject(document, precision);
	int n1 = spline_linear->GetPointCount();
	Vector* gp = spline_linear->GetPointW();

	// define point and polygon count

	const Int32 polyCnt = n1;
	const Int32 pointCnt = 4 * n1;

	// create polygon object
	PolygonObject* const polygonObject = PolygonObject::Alloc(pointCnt, polyCnt);

	// insert object into the document
	document->InsertObject(polygonObject, nullptr, nullptr);

	// access point and polygon data
	Vector* const points3 = polygonObject->GetPointW();
	CPolygon* const polygons = polygonObject->GetPolygonW();


	for (int i = 0; i < n1 - 1; i++) {

		// set points
		points3[4 * i] = gp[i];
		points3[4 * i + 1] = gp[i + 1];
		points3[4 * i + 2] = Vector(gp[i + 1].x, 100, gp[i + 1].z);
		points3[4 * i + 3] = Vector(gp[i].x, 100, gp[i].z);

		// set polygon
		polygons[i] = CPolygon(4 * i, 4 * i + 1, 4 * i + 2, 4 * i + 3);
	}

	points3[4 * (n1 - 1)] = gp[n1 - 1];
	points3[4 * (n1 - 1) + 1] = gp[0];
	points3[4 * (n1 - 1) + 2] = Vector(gp[0].x, 100, gp[0].z);
	points3[4 * (n1 - 1) + 3] = Vector(gp[n1 - 1].x, 100, gp[n1 - 1].z);

	// set polygon
	polygons[n1 - 1] = CPolygon(4 * (n1 - 1), 4 * (n1 - 1) + 1, 4 * (n1 - 1) + 2, 4 * (n1 - 1) + 3);



	BaseTag* phongTag = polygonObject->MakeTag(Tphong);

	polygonObject->Message(MSG_UPDATE);
}

I wonder What has gone wrong?
The thing builds nice polygonal object, but it is not smooth! ![alt text]

What a nice and comprehensive answer!

Thank you so much! Everything is crystal clear now!

Dear c4d fellows,
I'm building polygonal objects using c++ in cinema4d (r20).

I have a small question.
I need to create phong tag to make my polygonal surface smooth.
Do I need to ascribe phong tag to each polygon constituing the surface or a single phong tag to the whole surface?

I scanned through different sources of c4d forums and met no formal math definition of a phong angle.
Does somebody have a good source with explanation of phong angle in cinema 4D?

Also, as far as I understand I can easily set up the normal direction to orient the polygons correctly.
Here is a very self explaining example from sdk:

https://developers.maxon.net/docs/Cinema4DCPPSDK/html/page_manual_normaltag.html

But I heard that phong tag might override normal tags.
It is quite scary.

Suppose I set up my normals for each polygon of my surface (with love and care). Then I introduce phong tag and ... all my normals will be destroyed?

Yaroslav.

@ferdinand
Oh, thanks!
Quite a nice idea!

Ferdinand,
just tried

LineObject* spline_linear = spline->GetLineObject(document, precision);

Works like a charm. The closer float "precision" to one the better the approximation, as far as I understand.

One thing, that confuses me is that new object appear in c4d menus with little white"question mark" sign (see picture).
I don't undersytand why.

Here is my piece of code:

LineObject* spline_linear = spline->GetLineObject(document, 0.9);
document->InsertObject(spline_linear, NULL, NULL, 0); // Add it to the OM
spline_linear->Message(MSG_UPDATE);

Oh, I see. Now I can extract all the points from this LineObject and construct a simple linear spline if I need one.
I guess cinema4d doesn't recognize the LineObject. Hence, question mark in menus.

@ferdinand

Dear Ferdinand, thank you for
the comprehensive answer!

(Dear mp5gosu, thank you for your comment too)

Dear Ferdinand, I develop plugin in c++ (using vs2019 and c4d r20) and this is precisely what I meant.
Instead of using beautiful and smooth bezier-curved type splines I want to substitute them with finely approximated linear splines (and I guess SplineObject::GetLineObject is precisely the function I need.) I wonder if there is some control on the number of linear segments approximating the spline. Hopefully, I can get it from the corresponding class declaration.

Yaroslav.

Dear c4d fellows,
I wonder, if there is a buit in method in SplinObject to turn Bezier spline into interpolating linear spline.
Of course, it is simple to code my own function doing exactly this, but may be it is already implemented by c4d creators.

Yaroslav.

@m_magalhaes

Thank you, Manuel!