Replace Grease Pencil object with a mesh object and vice versa

Question

I am sketching an environment scene, wherein I want to draw the location for trees as a Grease Pencil object. So that I can create a more appropriate floor plan design. When I am done sketching, I want to replace the Grease Pencil objects with the actual tree meshes. So I was wondering, considering I keep the object origins in-tact by duplicating the Grease Pencil trees, can I replace them with the mesh object? And the other way around, can I also replace a mesh with a Grease Pencil object?

The Link/ Transfer data menu pop-up (Ctrl+L) doesn't allow me to link the object data between different object types.

If this is possible with a script that can be placed in the Ctrl+L menu that would also be fine with me.

Answer 1

You can't change an object's data type once it has been created. Here's a suggestion that will create new objects and copy the data in the same location as the selected objects.

import bpy


class SimpleOperator(bpy.types.Operator):
    bl_idname = "object.simple_operator"
    bl_label = "Replace Selected By Active"
    bl_options = {"REGISTER", "UNDO"}
    
    delete_selected: bpy.props.BoolProperty(default=True, name="Delete Selected")

    @classmethod
    def poll(cls, context):
        return len(context.selected_objects) > 1

    def execute(self, context):
        source = context.active_object
        for obj in context.selected_objects:
            if obj == source:
                continue
            new = bpy.data.objects.new(name=source.name, object_data=source.data)
            source.users_collection[0].objects.link(new)
            new.matrix_world = obj.matrix_world
            # If you don't want the new objects to inherit scale & rotation, use this :
            # new.location = obj.location
            if self.delete_selected:
                bpy.data.objects.remove(obj)
            new.select_set(True)
        return {'FINISHED'}

def menu_func(self, context):
    self.layout.operator(SimpleOperator.bl_idname, text=SimpleOperator.bl_label)

def register():
    bpy.utils.register_class(SimpleOperator)
    bpy.types.VIEW3D_MT_make_links.append(menu_func)


def unregister():
    bpy.utils.unregister_class(SimpleOperator)
    bpy.types.VIEW3D_MT_make_links.remove(menu_func)


if __name__ == "__main__":
    register()