[Tutorial] SketchUp Ruby C Extension

jefftrull

I was so excited to discover that someone was building Sketchup extensions with Visual Studio 2010 - that's exactly what I need to do - unfortunately, after going through the whole process, I can't seem to successfully load the SX_HelloWorld module:


require 'SX_HelloWorld'
Error; #<LoadError; C;/Program Files/Google/Google SketchUp 8/Plugins/SX_HelloWorld.so; 126; The specified module could not be found.   - C;/Program Files/Google/Google SketchUp 8/Plugins/SX_HelloWorld.so>
(eval)
(eval);0

Notice this is not a situation where the file is missing - that produces a similar but different error message.

After some Googling it seemed like missing .so's are sometimes the culprit, so I tried copying over some from my Ruby build directory (win32ole.so and Win32API.so), but it didn't help. Finally I tried running Sketchup from the VS2010 command line shell - this resulted in the infamous "bugsplat".

I'm at my wit's end here... any ideas?

Thanks,
Jeff
PS: My Ruby install gives RUBY_PLATFORM=i386-mswin32_100, RUBY_VERSION=1.8.6; Sketchup gives RUBY_PLATFORM=i386-mswin32 and the same version

Dan Rathbun

FYI: When require loads a shared object library file (and not a ruby script,)
the require(filepath) method looks for a C function named:
"Init_" + File.basename( filepath, File.extname(filepath) )
and runs it after loading the shared library.

This means that named C function must exist (even if it does nothing,) and must be named exactly as the file is named (CASE SENSITIVE.) If an enduser renames the so (or dll, dylib, etc.,) file later (including changing the case of any characters,) then loading the library file with require() will fail. (usually resulting in a "entry point not found" error.)

jefftrull

Thanks for the quick response! Unfortunately, I don't think that's the issue, for three reasons:

The error message is "The specified module could not be found", rather than "entry point not found"
I'm using the example file from bitbucket unchanged... the name of the relevant function there is "Init_SX_HelloWorld", vs filename "SX_HelloWorld.so"
I can use this module OK in Ruby standalone (whichever one I built with)

I do think it's got to be something simple... I just can't see what it might be. The error message isn't terribly helpful

Dan Rathbun

BTW your on Windows 7 ??

Is the path:
%(#BF0080)["C:/Program Files (x86)/Google/Google SketchUp 8/Plugins/SX_HelloWorld.so"]

and what is the result of (at the console):
puts $LOAD_PATH

jefftrull

@dan rathbun said:

BTW your on Windows 7 ??

That's right, Windows 7 Professional SP1

@unknownuser said:

Is the path:
%(#BF0080)["C:/Program Files(x86)/Google/Google SketchUp 8/Plugins/SX_HelloWorld.so"]

No, it's "C:/Program Files/Google/Google Sketchup 8/Plugins/SX_HelloWorld.so" (no "(x86)")

@unknownuser said:

and what is the result of (at the console):
puts $LOAD_PATH


puts $LOAD_PATH
C;/Program Files/Google/Google SketchUp 8/Plugins
C;/Program Files/Google/Google SketchUp 8/Tools
nil

Thanks!

thomthom

@jefftrull said:

I can use this module OK in Ruby standalone

Hm... it works in IRB, but not SketchUp?

@jefftrull said:

(whichever one I built with)

Exactly what version of Ruby did you use to build the extension?
Also - did you remember to modify the config.h file as described in the README?

thomthom

The error you report is mentioned in this article: http://apocryph.org/2007/06/16/totally_bullshit_ruby_extension_experience_windows/

However, I did not experience such error... not really sure what the difference is here...

Dan Rathbun

@jefftrull said:

@dan rathbun said:

BTW your on Windows 7 ??

That's right, Windows 7 Professional SP1

@unknownuser said:

Is the path:
%(#BF0080)["C:/Program Files(x86)/Google/Google SketchUp 8/Plugins/SX_HelloWorld.so"]

No, it's "C:/Program Files/Google/Google Sketchup 8/Plugins/SX_HelloWorld.so" (no "(x86)")

So (just to be clear:

1) You installed the 32bit version of Windows 7 ??

2) Are you running Sketchup with the Google supplied "msvcrt-ruby18.DLL" (which is v1.8.6-p287,) or did you replace the "msvcrt-ruby18.DLL" library file in the Sketchup program dir, with the one that you built ??

Dan Rathbun

.. and did you try: require('SX_HelloWorld.so')
(ie, specifying the extension, which should skip the search for a "SX_HelloWorld.rb" file.)

jefftrull

thomthom, thanks for your help. I've suddenly found a formula that works. The key thing is to use the Ruby built from the one-click installer you reference in the README http://rubyforge.org/frs/download.php/47082/ruby186-27_rc2.exe
I hope it doesn't go away anytime soon (it's no longer listed on their index page) - I'm glad you had the direct link, because using either of the two Ruby builds I made from source (one VS2008, one VS2010) fails.

To answer your questions:

yes, it works in irb for all three Ruby builds without problems
I did the config.h hack for the one-click version, but for the VS2008 and VS2010 I was able to compile the extension with the same version of VC++ I used to build Ruby itself, so it wasn't necessary... I think?
All Ruby versions were 1.8.6-p287, chosen to match SketchUp
The apocryph report relates to the need to embed a manifest into the .so file. Following that advice allowed me to compile under VS2008 - under VS2010 no manifest was produced (and its integration was apparently unnecessary)

jefftrull

Thanks again for considering this problem of mine, Dan. As you can see from my previous message, it's now working, but I'm still not sure what was wrong.

@unknownuser said:

So (just to be clear:

1) You installed the 32bit version of Windows 7 ??

Looks like it. "system properties" says "32-bit operating system"

@unknownuser said:

2) Are you running Sketchup with the Google supplied "msvcrt-ruby18.DLL" (which is v1.8.6-p287,) or did you replace the "msvcrt-ruby18.DLL" library file in the Sketchup program dir, with the one that you built ??

That's an interesting question. I haven't changed anything in the Sketchup program dir, beyond copying the SX_HelloWorld.so into Plugins. What is the significance of those msvcrt* files?

Thanks,
Jeff

thomthom

Ah, so you initially used a Ruby version you built yourself?
I don't really know what makes the difference there. I just tried to find a minimum work solution - so I started out with a pre-built Ruby.

@jefftrull said:

I did the config.h hack for the one-click version, but for the VS2008 and VS2010 I was able to compile the extension with the same version of VC++ I used to build Ruby itself, so it wasn't necessary... I think?

Dunno - you might not need it if you built Ruby yourself. The version you had might not have that check in it. With the pre-built version I used I had to remove that check otherwise it would not compile.

Dan Rathbun

@jefftrull said:

That's an interesting question. I haven't changed anything in the Sketchup program dir, beyond copying the SX_HelloWorld.so into Plugins. What is the significance of those msvcrt* files?

It's THE Ruby interpreter that the Sketchup executable loads. (Copied from the pre-built v1.8.6-p287 binary package.)

The one that your full Ruby install (ruby.exe and rubyw.exe,) loads is in the "bin" subdir of the full install folder heirarchy.
see: Ruby Interpreter DLLs (Win32)

and making sure you saw this link list: [Info] C/C++ Ruby extensions & SketchUp plugins

jefftrull

Thanks again for the helpful information, Dan. I gathered from the "Ruby Interpreter DLLs" link that you can replace the interpreter used by Sketchup with a different one; indeed that seemed to work, but it made no difference in my ability to load the .so file. Still works OK in irb (when the compiler versions match), fails in Sketchup. The good news is it doesn't really matter - I have a working recipe now. The one-click binary is the only thing that's worked for me over all the combinations, and with that, either VS2008 or VS2010 works fine.

I'm off to turn this into a CMake recipe (this application is cross-platform); would anyone be interested in seeing that when it's done?

Cheers,
Jeff

Dan Rathbun

Be aware that Mac Sketchup still distro's with Ruby v1.8.5 initial release.

thomthom

@jefftrull said:

I'm off to turn this into a CMake recipe (this application is cross-platform); would anyone be interested in seeing that when it's done?

Yes! If you want to add it to the existing project just let me know. I think you can just make a pull request anyway (though I've never used this feature.)

I know that Dana tried to set up a CMake project - which AFAIK failed under SU. So a lean clean CMake bare bone recipe would be very much welcome!

jefftrull

Let's see how this works for people. Tested only under Windows, although I tried to make the analogous changes for OSX based on my reading of extconf.rb. This file is intended to live under "src" and will create targets for both extensions.

CMake control file for Sketchup Ruby C Extension

thomthom

@jefftrull said:

Let's see how this works for people. Tested only under Windows, although I tried to make the analogous changes for OSX based on my reading of extconf.rb. This file is intended to live under "src" and will create targets for both extensions.

Sorry, haven't had time to look at this yet. I've got quite a list of things to do for the time being...

chyn2000

Hey guys,

So, I got the ruby extension process to work, but I seem to be running into one little catch... multithreading.

FYI: I'm using Pelle's C with the options TBD suggested in his SUExt example. I'm on a Win 7 (64 bit) system (though hopefully that won't matter).

I'm trying to use _beginthread, but using TBD's settings, it seems I have an unresolved symbol '_beginthread'.

Just to let you know, I am kind of new to multithreading and DLLs. I have created threaded applications, but never a threaded dll.

Taking an example program that I have gotten to compile and run as a standalone app (pelle's C option multithreaded (lib)), I add the libs, includes and functions required to make it a ruby extension and it suddenly can't resolve _beginthread.

A couple of modifications to TBD's project settings and I get it to compile and even be recognized by the irb. However, it seems the second the thread tries to run, the whole irb closes.

The settings I modified to "get it to work" was:
Runtime library from multithread (dll) to multithread (lib)
and turn off "Omit default library in object files"

Any ideas?

Thanks,
Reg


// general Windows
#pragma comment(lib, "kernel32.lib")
#pragma comment(lib, "gdi32.lib")
#pragma comment(lib, "user32.lib")
#pragma comment(lib, "shell32.lib")
#pragma comment(lib, "advapi32.lib")

// Ruby
#define HAVE_ISINF 1  // isinf macro redefinition workaround
#pragma comment(lib, "msvcrt-ruby18.lib");

// DLL
#pragma comment(lib, "crt.lib");

#include <stdio.h>
#include <windows.h>
#include <process.h>         // needed for _beginthread()
 
// Ruby headers 
#include "ruby.h"

void  silly( void * );       // function prototype

// De fining a space for information and references about the module to be stored internally
VALUE KMRH = Qnil;

int j = -1;

// our function
VALUE method_display_model(VALUE self, VALUE input)
{
    // Our program's first thread starts in the main function.
    printf( "Now in the main function.\n" );

    // Let's now create our second thread and ask it to start
    // in the silly() function.
//    _beginthread( silly, 0, (void*)12 );  //Commented out to see if the program would stay alive and it does

    // From here on there are two separate threads executing
    // our one program.

    // This main thread can call the silly() function if it wants to.
	while(j != 0)
	{
    	silly( (void*)j );
		j--;
	}

    Sleep( 10000 );

	int i = NUM2INT(input);
	return INT2NUM(i + 1);
}

// The initialization method for this module
void Init_KMRH(void)
{
	KMRH = rb_define_class("KMRH", rb_cObject);
	rb_define_method(KMRH, "display", method_display_model, 1);
}


void  silly( void *arg )
{
	int k = 10;
	while(k-- != 0)
	{
//    	printf( "The silly() function was passed %d\n", (INT_PTR)arg );
    	printf( "The silly() function was passed %d\n", k );
	}
}

thomthom

That's way beyond me. I've not dealt with threading at all. But I'll be keeping an eye on this as it something I might want to do in the future.