I''m trying to abstract some of my OpenGL drawing procedures into a DLL so I can make a program that will load plugins. Whenever I try to draw from inside the DLL, I can''t seem to escape the "unresolved external" errors. I''ve tried everything I can think of to get around this, but with no luck. Is this even possible, or am I beating my head against a brick wall? I though this might have something to do with scope limitations inherent of the rendering context. I''d really appreciate any feedback anyone could offer.

your dll uses opengl32.lib and the others you need in the settings?

we wanna play, not watch the pictures

If you are calling DLL functions from your main program, you need to export the functions with a .def file.

So, say you have a CalcNormal function to calculate normals in your DLL, you need to declare the function as extern and then create a .def file for your project that contains the following:

EXPORT

functionname1
functionname2
functionname3


So, for calcnormal it would be:

EXPORT

CalcNormal

BTW: comments in this file use the ; character, and details on .def files are in MSDN.

Hope that helps

you can also declare the functions/classes as

__declspec(dllexport) -- for your DLL compile
or
__declspec(dllimport) -- for your program compile

This may be MSVC specific. I think it worked in Dev-C++ though.

Usually this is done with a conditional define (that''s how I did it in PortaLib)


~~~
Cheers!
Brett Porter
PortaLib3D : A portable 3D game/demo libary for OpenGL

It depends on the compiler. In Borland C++ Builder it makes it very easy by not needing to put the libarys for nearly everything in the project.

As far as Importing and Exporting, BCB works like brettporter said MSVC works, but it does it alot more eaisly and dynamicly. I think that this feature of BCB has been used in MSVC if you have it. You need to put somthing like EXPORT in front of functions you want to export and the compiler will change the definition of EXPORT depending on what it is compiling (it works somthing like that, read the manual to find out the specifics.)

Also when asking a question like this, it is usualy a good idea to say what compiler you are using.

ANDREW RUSSELL STUDIOS
Web site coming soon...

^Bump this up^

( I gotta learn this too.. I recently learned the basics of dll loading, but I get the unresolved external errors too.. I was trying to make tutorial 23 using .dll files )


Hey..... that''s a good point.. if one of you guys that are experienced with .dll files could rewrite the code from tutorial 23 using dlls, and post the code for download, then we could see clearly how to use OpenGL in dlls..

~Cobra~