Compiling LightWave Plug-ins
LightWave plug-ins on all platforms are ordinary operating system objects (they're DLLs under Windows, for example), so building them is pretty straightforward. You'll need to define a couple of preprocessor symbols and export one variable name, and you'll need to compile and link with a bit of code supplied with the SDK. LightWave plug-ins are ordinarily given a ".p" filename extension, although this isn't required.
Preprocessor Symbols
The SDK header files rely on preprocessor symbols to identify the operating system and
CPU of the host system. These are currently used to define system-XCALL_
macro and the HostDisplayInfo
structure (don't worry if you don't
know what those are yet), and they determine what is stored in the system identification
fields of the module descriptor. The operating system defines are
_WIN32 /* Microsoft Windows */ _MACOS /* Macintosh */ _XGL /* Unix */
and the CPU defines are.
_X86_ /* Intel and Intel-compatible */ _ALPHA_ /* Alpha AXP */ _PPC_ /* PowerPC */ _MIPS_ /* MIPS */
You need one symbol from the first list and one from the second, and you need to pass them to the compiler as preprocessor defines.
Exported Variable
The linker needs to export the symbol _mod_descrip
. LightWave looks for this
module descriptor data structure by name when it attempts to load a plug-in. Symbol export
is handled differently in different development environments, but it's often a linker
command line option.
SDK Library
The SDK ships with source code files defining the _mod_descrip
structure,
default Startup
and Shutdown
functions, and a default names array. Each
plug-in you create must include servmain.c
and must be linked with server.lib
.
Before compiling any plug-ins, you'll need to build server.lib
for your
system. Create a statically linked library containing servdesc.c
, username.c
,
startup.c
, and shutdown.c
, all of which you should find in the SDK/source
directory. Name the library server.lib
. Define the operating system and CPU
preprocessor symbols described previously when compiling the library source.
You may want to create more than one version of server.lib
with different
compiler settings (debug and release versions, for instance).
Debugging Notes
Don't forget that before you can run or debug your plug-in for the first time, you need to add it to the plug-in list in LightWave.
In general, you must quit and restart LightWave each time you rebuild your plug-in and want to run it. Your plug-in is cached in memory for the life of a LightWave session, so LightWave won't see the changes to your plug-in until it quits and restarts.
LightWave Modeler supports a debug command line switch. When started with the -d switch, Modeler adds an "Unload Plug-ins" command. (This appears in the Modeler/Plug-ins menu with the default configuration, but may not appear in custom menu configurations.) Activating this command forces Modeler to unload all unlocked plug-in modules, so that when you execute your plug-in again it will be reloaded from disk.
Beginning in LightWave 6.5, Modeler's -d switch can take an argument (-dfilename) which tells it where to write debug information. This can be useful for figuring out why plug-ins aren't loading, or for looking at trace information generated by XPanels.
Microsoft Windows
Plug-in modules under Windows are Win32 dynamic link libraries (DLLs). You don't need
to create an import library (.lib) or an export file (.exp) for plug-in DLLs, but you will
need to export _mod_descrip
. One way to do this is to include a module definition
(.def) file containing an EXPORT _mod_descrip
directive. You can use the default source\serv.def
file provided with the SDK for this.
Win32 DLLs have a standard entry point function named DllMain
. You don't need
to provide a DllMain
for your LightWave plug-ins unless, for example, the user
interface is built with Windows interface components that require the DLL's instance
handle. (But consider building your interface using the platform-independent components
provided with the plug-in SDK.)
The alignment of structure members in your DLL must match LightWave's.
Data type | Address must be... |
char |
any |
short (16-bit) |
even |
int, long (32-bit) |
divisible by 4 |
float |
divisible by 4 |
double |
divisible by 8 |
structures |
aligned for the largest member |
unions |
aligned for the first member |
The recipes for specific compilers discuss what, if anything, you need to do to ensure that your plug-in's data is properly aligned.
If you decide to use makefiles to build your plug-ins, they should contain lines resembling the following:
LWSDK_FLAGS = -D_X86_ -D_WIN32 .c.obj: $(CC) $(CFLAGS) $(LWSDK_FLAGS) $*.c $(LWSDK_SRC)servmain.c .obj.p: $(LINKER) -dll -out:$@ -def:$(LWSDK_INCL)serv.def $*.obj \ $(LWSDK_LIB)server.lib $(OTHER_LIBS)
In other words, define the symbols _X86_
(or _ALPHA_
) and _WIN32
,
include servmain.c
in the list of source code files, include the module
definition file serv.def
so that _mod_descrip
is exported, and link with
server.lib
.
Microsoft Visual C++
To build an MSVC version of the SDK library,
- Create a new project workspace, or insert a new project into an existing workspace. The
project type should be "Static Library." Name the project "
server
". - Settings dialog, C/C++ tab, add
_X86_
(or_ALPHA_
) and_WIN32
to the preprocessor definitions field. - In the field for additional include directories, type the path to the plug-in SDK
include
directory. - Add
servdesc.c
,username.c
,startup.c
, andshutdown.c
to the project. These are located in theSDK\source
directory. - Build
server.lib
.
To create a plug-in,
- Create a new project workspace, or insert a new project into an existing workspace. The project type should be "Dynamic-Link Library."
- Settings dialog, C/C++ tab, add
_X86_
(or_ALPHA_
) and_WIN32
to the preprocessor definitions field. - In the field for additional include directories, type the path to the plug-in SDK
include
directory. - Add your source files to the project. Also add
servmain.c
,server.lib
andserv.def
.
Accept the default settings for the calling convention (__cdecl), alignment (8 byte)
and runtime library (multithreaded or multithreaded debug, for the release and debug
versions, respectively). If you've built both debug and release versions of server.lib
(and this is recommended), make sure you list the appropriate one for the debug and
release versions of your plug-in.
You're ready to build your plug-in. To debug it,
- Settings dialog, Debug tab, enter the full path to
lightwav.exe
ormodeler.exe
, as appropriate, in the field labeled "Executable for debug session." - Set the working directory to the directory containing the LightWave executables.
- Build a debug version of your plug-in.
Hit F5 to begin debugging. The debugger will warn you that the LightWave executable doesn't contain any debugging information, but that's okay. Your plug-in does have this information, which the debugger will find as soon as your plug-in is started by LightWave.
Borland C++ 4.52
Information provided by Michal Koc.
Before creating any plug-ins, you'll need to build a Borland version of the SDK library.
- Create a new project
- Set the Target Type to Static Library (for .dll) [.lib]
- In Standard Libraries, mark Static
- Set the Platform to Win32
- Set the Target Model to GUI
- Add nodes with the files
servdesc.c
,username.c
,startup.c
, andshutdown.c
- Options/Project/Directories, set the include and lib paths
- Options/Project/Compiler/Defines, add
_X86_
and_WIN32
- Options/Project/Compiler/Code Generation, set fastthis
- Options/Project/32-bit Compiler, set Processor and Data alignment to 8 bytes
- Compile
To build a plug-in,
- Create a new project
- Set the Target Type to Dynamic Library [.dll]
- In Standard Libraries, mark Dynamic
- Set the Platform to Win32
- Set the Target Model to GUI
- Add nodes with
servmain.c
,server.lib
, and your source files; remove unused nodes - Options/Project/Directories, set include and lib paths
- Options/Project/Compiler/Defines, add
_X86_
and_WIN32
- Options/Project/Compiler/Code Generation, set fastthis
- Options/Project/32-bit Compiler, set Processor and Data aligment to 8 bytes
- Compile
GNU gcc/Mingw32
Information provided by Dan Maas
You can build LightWave plug-ins with Win32 GNU distributions. The procedure given here was developed and tested with the Mingw32 distribution.
Before creating any plug-ins, you'll need to build a GNU version of the SDK library. (Some of the command lines below wrap to a second line here, but they should be entered on a single line.)
cd
to the SDKsource
directory.- Compile the library sources.
gcc -c -D_WIN32 -D_X86_ -O6 -I$(LWSDK_INCL) servmain.c servdesc.c username.c startup.c shutdown.c
- Assemble the library.
ar r libserver.a servdesc.o username.o startup.o shutdown.o
To build a plug-in,
- Compile your source files.
gcc -c -D_WIN32 -D_X86_ -O6 -I$(LWSDK_INCL) myplug.c
- Link to the SDK library and generate a DLL.
dllwrap -o myplug.p --export-all --dllname myplug.p myplug.o $(LWSDK_LIB)servmain.o $(LWSDK_LIB)libserver.a
An equivalent makefile would look like this:
LWSDK_CFLAGS = -D_WIN32 -D_X86_ -O6 %.o: %.c gcc $(LWSDK_CFLAGS) -I$(LWSDK_INCL) -c $< myplug.p: myplug.o dllwrap -o $@ --export-all --dllname $@ \ myplug.o $(LWSDK_LIB)servmain.o $(LWSDK_LIB)libserver.a
Watcom C++ 10.0a
(On June 30, 1999, Sybase, Inc., sent an "end of life" letter to registered owners of Watcom C/C++ announcing that version 11.0 of the compiler would be its last. Watcom is therefore unlikely to play a role in future LightWave plug-in development. This section remains useful, however, as an illustration of the incompatibilities you may encounter with some compilers.)
In Watcom terminology, plug-ins are NT DLLs, so that should be your target type. server.lib
should also be built as an NT object.
To build a plug-in,
- Add the SDK include directory to the include path [-i]
- Disable stack depth checking [-s]
- Add macro definitions [-d]
_X86_
and_WIN32
- Change char default to signed [-j]
- Use 8-byte structure alignment [-zp8]
- Use the 32-bit flat memory model [-mf] (the default)
- Use the stack-based calling convention [-5s]
- Export [exp]
_mod_descrip
There's an important mismatch in calling conventions that apparently can't be solved with a compiler switch or a pragma. When using the stack-based calling convention, which plug-ins must, Watcom 10.0a expects functions that return floating-point numbers to put them in specific registers, while LightWave's code leaves them at the top of the FPU stack. You'll encounter this whenever a plug-in compiled with Watcom needs to call a plug-in SDK function that returns a double.
What happens can be illustrated with a little assembly-ish pseudocode. Given
double routine( void ); double result; result = routine();
the different ways the function call is handled are
Microsoft: call routine fstp result ; pop ST(0) into result Watcom: call routine mov result, eax ; move edx:eax into result mov result+4, edx
When compiled in Microsoft Visual C++, routine
leaves its return value at the
top of the FPU stack, which is popped into result
. In Watcom 10.0a, routine
leaves its return value in the register pair edx:eax
, which is then mov
ed
into result
.
The workaround for this involves adding a bit of inline assembly language to each source file that contains a call to a LightWave function returning a double. At the beginning of each such file, put
static double fac; /* floating point accumulator */ extern void sdk_fstp( void ); #pragma aux sdk_fstp = "fstp fac" #define SDK_DBLRTN( x ) \ sdk_fstp(); \ x = fac;
This uses Watcom inline assembly to load the contents of ST(0) into a fixed memory location, from which the value can be copied. Calls that would look like this
result = objInfo->dissolve( objID, t );
must be changed to
objInfo->dissolve( objID, t ); SDK_DBLRTN( result );
The SDK function is called without assigning its return value. The assembly instruction
fstp fac
is inserted after the call to retrieve the return value, then fac
is copied into result
.
Macintosh
Plug-in modules on the Mac are PowerPC shared libraries of type shlb
.
Metrowerks CodeWarrior
Before compiling any plug-ins, you'll need to build a CodeWarrior version of the SDK library.
- Create a new, empty project.
- Target Settings/Linker, choose Mac OS PPC Linker.
- PPC Target/Project Type, choose Library.
- PPC Target, name the file
server.lib
. - PPC Processor, set alignment to PowerPC (the default).
- Define the
_MACOS
and_PPC_
preprocessor symbols. - Access Paths/Systems Paths, add the SDK include directory.
- Add
servdesc.c
,username.c
,startup.c
, andshutdown.c
. These are located in the SDKsource
directory. - Build.
To create a plug-in project,
- Create a new, empty project.
- Target Settings/Linker, choose Mac OS PPC Linker.
- PPC Target/Project Type, choose Shared Library.
- Define the
_MACOS
and_PPC_
preprocessor symbols. - Access Paths/Systems Paths, add the SDK include directory.
- PPC PEF/Export Symbols, choose the method you'll use to export
_mod_descrip
. See the CodeWarrior shared library documentation for an explanation of the available methods. - C/C++ Language, turn on Relaxed Pointer Type Rules and Enums Always Int.
- Add your source code files to the project, along with
servmain.c
. - Add
server.lib
andMSL Runtime-PPC.Lib
to the project. If the plug-in calls Mac Toolbox routines, you'll also need to addInterfaceLib
(orCarbonLib
if you're compiling for OS X), but consider building your interface using the platform-independent components provided with the plug-in SDK instead.
You can globally define _MACOS
and _PPC_
by putting them in a .h file
and using that file as the C/C++ Language Prefix File (in Language Settings). To export _mod_descrip
,
you can create a text file containing simply "_mod_descrip". Call the file server.exp
.
In PPC PEF/Export Symbols, choose the "Use .exp file" method, and then add server.exp
to the project.
In later versions of CodeWarrior, you may find that the compiler won't accept any sort of conversion between char * and const char *. To work around this, you can add the following pragma:
#pragma old_argmatch on
Building plug-ins for OS X isn't much different from building them for previous
operating systems on the Mac, but you must link with CarbonLib
instead of InterfaceLib
,
and your code must be Carbon compliant. See the Carbon
Porting Guide (an Adobe Acrobat PDF) at Apple's Developer
website.
CodeWarrior up to version 6.2 cannot debug on OS X. Debugging in MacOS 9 is sufficient in most cases, but if you need to debug in X, you can use gdb in a terminal window.
As of this writing, LightWave for OS X is a CFM application. When a CFM app is run, OS
X actually runs a mach-o wrapper app that loads the program. The wrapper is called LaunchCFMApp
,
located in
/System/Library/Frameworks/Carbon.framework/Versions/A/Support/ LaunchCFMApp
To begin debugging, use gdb to run LaunchCFMApp
.
localhost% gdb /System.../LaunchCFMApp
In gdb, type run
followed by the name and path for the LightWave component in
which your plug-in runs.
Macintosh Programmer's Workshop
Information provided by Mark Nutter
Before building any plugins, you'll need to build an MPW version of the SDK library:
- In the MPW worksheet, select "Set Directory..." from the Directory menu and
set the working directory to the
source
directory of the SDK. - Select "Create Build Commands..." from the Build menu.
- Enter
server.lib
as the Program Name. - Select "Static Library" as the Program Type.
- Check "PowerPC Only" as the Target.
- Add
servdesc.c
,startup.c
,shutdown.c
andusername.c
as the Source Files. These are in the SDKsource
directory. - Click the Include Search Paths button and Add the SDK
include
directory. - Click the PowerPC Options button and enter
-d _MACOS -d _PPC_
in the "C Options" field. - Click the Create Make button to generate a makefile for
server.lib
. - Select Build (Cmd-B) from the Build menu. The program name should come up as
server.lib
by default. Click OK to buildserver.lib
. You will get a warning that "serverData" is not used within function "Shutdown", which you can ignore.
To build a plugin:
- Select "Set Directory..." from the Directory menu and set the working directory to the directory containing your plug-in's source files.
- Select "Create Build Commands..." from the Build menu.
- Enter your plug-in's name as the Program Name.
- Select "Shared Library" as the Program Type.
- Check "PowerPC Only" as the Target.
- Add the source files for your plug-in. Also add
servmain.c
(in the SDKsource
directory) and theserver.lib
you created. - Click the Include Search Paths button and Add the SDK
include
directory. - Click the PowerPC Options button and enter
-d _MACOS -d _PPC_ -typecheck relaxed
in the "C Options" field. - Click the Exported Symbols button and enter
_mod_descrip
in the Export Symbols box. - Click the CreateMake button to create your makefile.
- Build (Cmd-B).
Unix
Plug-in modules under Unix are shared object modules, or DSO files. When compiling,
remember to define both _XGL
and the preprocessor symbol for your CPU. _mod_descrip
must be exported from the DSO, and servmain.o
must be among the objects passed to
the linker. The link line should include any other libraries that the plug-in would need
as a stand-alone program.
.o.p: ld -shared -exported_symbol _mod_descrip -L$(SDK_LIB) \ $(SDK_LIB)servmain.o $*.o -o $@ -lserver.lib $(OTHER_LIBS)