How can I access the actual structure of a Mesh datablock in memory using the value returned from bpy.types.Mesh.as_pointer() In 2.79 Blender there used to be a possibility to do that by just passing the pointer value to your C++ module or Python's ctypes and referencing that pointer with an appropriate type. Example for 2.7 can be seen here: https://blenderartists.org/t/exporting-triangles-api-challenges/694524/2
However, when I access it the same way in 2.8, I get a struct which is 0-ed. It does contain a valid ID sub-struct in it, but the rest of the data is nulled. Could that be the issue brought by the new depsgraph in 2.8?
C++ side:
#include "mesh_utils.hpp"
extern "C"
{
#include "bl_src/makesdna/DNA_mesh_types.h"
#include <blenkernel/BKE_editmesh.h>
#include <bmesh.h>
}
#include <iostream>
namespace bpy_boost
{
BlenderMesh::BlenderMesh(::std::uintptr_t mesh_pointer)
{
const Mesh* mesh = reinterpret_cast<const Mesh*>(mesh_pointer);
::std::cout << (uint32_t)mesh->totloop << ::std::endl;
}
}
Python side:
def execute(self, context):
from ..bpy_boost.src.bpy_boost import Mesh
ds = bpy.context.evaluated_depsgraph_get()
obj = bpy.context.view_layer.objects.active
object_eval = obj.evaluated_get(ds)
if object_eval:
mesh = object_eval.to_mesh()
if mesh:
mesh.calc_loop_triangles()
if not mesh.loop_triangles:
object_eval.to_mesh_clear()
mesh = None
if mesh:
if mesh.use_auto_smooth:
if not mesh.has_custom_normals:
mesh.calc_normals()
mesh.split_faces()
mesh.calc_loop_triangles()
if mesh.has_custom_normals:
mesh.calc_normals_split()
ptr = mesh.as_pointer()
Mesh(ptr)
return {'FINISHED'}
The validity of the pointer value between Python and C++ has been checked. Python-C++ interface is done with Cython and is not provided here since it is not important.
