GeomNode::add_geom crashes

C++ coding using Panda3D
1

Hi. I am trying to create some dynamic geometry with c++. As a simple test, I have started to adapt the cube example like the following:

#include <panda3d/pandaFramework.h>
#include <panda3d/geomTriangles.h>
#include <panda3d/geomPoints.h>
#include <panda3d/pandaSystem.h>


int main(int argc, char *argv[]) {
	// Open the framework
	PandaFramework framework;
	framework.open_framework(argc, argv);
	// Set a nice title
	framework.set_window_title("Panda Garten");
	// Open it!
	WindowFramework *window = framework.open_window();

	// Check whether the window is loaded correctly
	if (window != nullptr) {
		nout << "Opened the window successfully!\n";

		window->enable_keyboard(); // Enable keyboard detection
		window->setup_trackball(); // Enable default camera movement

		// Put here your own code, such as the loading of your models
		window->enable_keyboard();

		GeomVertexData geomData("particles", GeomVertexFormat::get_v3(), GeomEnums::UH_dynamic);
		auto vertex = GeomVertexWriter(&geomData, "vertex");
		vertex.add_data3f({-1, -1, -1});
		vertex.add_data3f({1, 1, -1});
		vertex.add_data3f({1, 1, 1});
		vertex.add_data3f({-1, -1, 1});

		auto tris = GeomTriangles(Geom::UH_dynamic);
		tris.add_vertices(0, 1, 3);
		tris.add_vertices(1, 2, 3);

		Geom geom(&geomData);
		geom.add_primitive(&tris);

		GeomNode geomNode("cubes");
		geomNode.add_geom(&geom);

		window->get_render().attach_new_node(&geomNode);

		// Do the main loop
		framework.main_loop();
	} else {
		nout << "Could not load the window!\n";
	}
	// Close the framework
	framework.close_framework();
	return 0;
}

This compiles fine and opens a window. But the line geom.add_primitive causes an invalid assertion.

dtool/src/dtoolbase/typeHandle.cxx:78: void TypeHandle::dec_memory_usage(TypeHandle::MemoryClass, size_t): Assertion `rnode->_memory_usage[memory_class] >= 0’ failed.

This is the stacktrace
image

I use the following cmake code to compile the project:

cmake_minimum_required(VERSION 3.15)

project(pandagarten)

set(CMAKE_CXX_STANDARD 14)
set(CMAKE_POSITION_INDEPENDENT_CODE ON)

find_package(Eigen3)

set(THREADS_PREFER_PTHREAD_FLAG ON)
find_package(Threads REQUIRED)

add_executable(pandagarten main.cpp)
target_link_directories(pandagarten PUBLIC /usr/lib/panda3d)
target_link_libraries(pandagarten
        Eigen3::Eigen
        Threads::Threads

        p3dtoolconfig
        p3dtool
        pandagl
        p3framework
        panda
        #           pandafx
        pandaexpress
        #           pandaphysics
        p3pystub
        p3direct
        )

My system is an up to date arch linux. The dynamic mesh python sample seems to work just fine.

Anyone have an idea what might be going on?

2

OK, got it now. I had to create a PT

            PT(GeomTriangles) tris;
	tris = new GeomTriangles(Geom::UH_dynamic);
	tris->add_vertices(0, 1, 3);
	tris->add_vertices(1, 2, 3);

	Geom geom(&geomData);
	geom.add_primitive(tris);