On 12/10/2013 at 01:04, xxxxxxxx wrote:
User Information:
Cinema 4D Version: r14
Platform:
Language(s) : C++ ;
---------
Hi,
I have been searching and trying for a while, now, but I can't get it to work to pass a variable from main (PluginStart) to my plugin, where I would like to read the value of that variable.
can someone explain how things like this work?
cheers,
Ello
On 12/10/2013 at 03:09, xxxxxxxx wrote:
Hi, you could go with a global variable for PODs (int, float, char, ...) and use it wherever you want in your entire plugin.
Int my_global_variable = 0; // allowed
String my_global_string; // (* ) not allowed because internal pointer table to the constructor is not build yet
String* my_global_string = nullptr; // correct!
Bool PluginStart()
{
my_global_string = NewObj(String);
if (!my_global_string)
return false;
// your code
return true;
}
void PluginEnd()
{
DeleteMem(my_global_string);
}
(* ) If you want to use a c4d class you can use a global pointer like String* and allocate it in PluginStart and Free it in PluginEnd.
Or you store some values in the global data container.
Cheers, Seb
On 12/10/2013 at 04:58, xxxxxxxx wrote:
i guess i dont't understand. in my main.cpp i have declared a boolean:
Bool test = false;
now i want to check this boolean inside another file (myPlugin.cpp)
BaseObject *myPlugin::GetVirtualObjects(BaseObject *op, HierarchyHelp *hh)
{
if (test) //do something
...
}
of course test is undeclared here. so my question is how can i grab the variable test inside GetVirtualObjects
On 12/10/2013 at 07:48, xxxxxxxx wrote:
You can use the extern keyword. See How do I share a variable between source files in C?
Best,
-Niklas
On 12/10/2013 at 08:56, xxxxxxxx wrote:
thank you. i tried this but still i must do something wrong.
in the main.cpp i have #include "myPlugin.h"
and in myPlugin.h i have
#ifndef _myPlugin_H_
#define _myPlugin_H_extern int myTest;
enum
{
...
when i try to compile i get the following error:
1> Main.cpp
1> myPlugin.cpp
1> Creating library C:\Program Files\MAXON\CINEMA 4D R14\plugins\myPlugin\obj\myPlugin\x64_Debug\myPlugin.cdl64.lib and object C:\Program Files\MAXON\CINEMA 4D R14\plugins\myPlugin\obj\myPlugin\x64_Debug\myPlugin.cdl64.exp
1>Main.obj : error LNK2001: unresolved external symbol "int myTest" (?isRegistered@@3HA)
1>myPlugin.obj : error LNK2001: unresolved external symbol "int myTest" (?isRegistered@@3HA)
1>C:\Program Files\MAXON\CINEMA 4D R14\plugins\myPlugin\myPlugin.cdl64 : fatal error LNK1120: 1 unresolved externals
i found this thread http://stackoverflow.com/questions/7004031/c-unresolved-externals but i dont understand what i need to do now...
On 12/10/2013 at 09:08, xxxxxxxx wrote:
Howdy,
Well, in everything I've read about c++ programming, there seems to be a consensus that global variables are frowned upon.
What I'd suggest is to create a static variable in your main.cpp file, and create accessor functions like this:
#include "MyPlugin.h"
static bool test;
bool PluginStart(void)
{
SetTest(false);
// rest of startup functions....
}
void SetTest(bool t)
{
test = t;
}
bool GetTest(void)
{
return test;
}
Then in your main header file (MyPlugin.h or whatever your plugin is named) you prototype the accessor functions:
void SetTest(bool t);
bool GetTest(void);
Then you simply include the main header file in each .cpp file where you need access to the "test" variable:
#include "MyPlugin.h"
//......
if(GetTest())
{
// do something
}
Adios,
Cactus Dan
On 12/10/2013 at 09:29, xxxxxxxx wrote:
thank you very much for the input..
still get the following error message:
1> myPlugin.cpp
1>myPlugin.obj : error LNK2001: unresolved external symbol "int __cdecl getTest(void)" (?getTest@@YAHXZ)
1>C:\Program Files\MAXON\CINEMA 4D R14\plugins\myPlugin\myPlugin.cdl64 : fatal error LNK1120: 1 unresolved externals
the thread i mentioned earlier said it is some problem with the linker. and since all those tests result in the same error i guess it must be some general setting i am missing??
EDIT: my fault. i mixed a uppercase letter ;) now working. many thanks !
On 12/10/2013 at 09:36, xxxxxxxx wrote:
Howdy,
Did you forget to include the header?
Adios,
Cactus Dan
On 12/10/2013 at 09:46, xxxxxxxx wrote:
i am happy, too, since this helped me solve the thing with my demo version of the plugin, too :)
On 14/10/2013 at 12:06, xxxxxxxx wrote:
It's quite easy as Niklas suggested.
In your main.cpp:
bool your_global_variable = false;
PluginStart()
{
your_global_variable = true;
}
In any other file (e.g. myPlugin.h) :
extern bool your_global_variable;
int any_function(int a, int b) //or anywhere else in this file
{
//do something with your_global_variable
return your_global_variable ? (a + b) : (a - b);
}
You don't need to include any file anywhere. You just need the declarations to make the scope see it.
Originally posted by xxxxxxxx
thank you. i tried this but still i must do something wrong.
in the main.cpp i have #include "myPlugin.h"
and in myPlugin.h i have
#ifndef _myPlugin_H_
#define _myPlugin_H_extern int myTest;
enum
{
...when i try to compile i get the following error:
[quote]
1> Main.cpp
1> myPlugin.cpp
1> Creating library C:\Program Files\MAXON\CINEMA 4D R14\plugins\myPlugin\obj\myPlugin\x64_Debug\myPlugin.cdl64.lib and object C:\Program Files\MAXON\CINEMA 4D R14\plugins\myPlugin\obj\myPlugin\x64_Debug\myPlugin.cdl64.exp
1>Main.obj : error LNK2001: unresolved external symbol "int myTest" (?isRegistered@@3HA)
1>myPlugin.obj : error LNK2001: unresolved external symbol "int myTest" (?isRegistered@@3HA)
1>C:\Program Files\MAXON\CINEMA 4D R14\plugins\myPlugin\myPlugin.cdl64 : fatal error LNK1120: 1 unresolved externals
i found this thread http://stackoverflow.com/questions/7004031/c-unresolved-externals but i dont understand what i need to do now...
[/QUOTE]