Go binding for SFML

[Dragnalith]

Some weeks go I fell in love of Go (golang.org), and because I really like SFML I would like to use it with Go.
There is no binding yet, so instead of waiting for someone doing, I should do it myself.

Right now, the only way to bind C++ to Go is using SWIG. I have read an old post speaking about SWIG. Are PySFML and rbSFML using SWIG ?
Is there some work used for the previous binding I can use ?

[Acrobat]

as i remember, GO can link with C libraries, i think you can make binding on top of C libs
check this : http://golang.org/doc/articles/c_go_cgo.html

[Dragnalith]

That's true, it's another possibilities, doing the Go binding from the C binding.
But it's a bit weird to do a binding from another binding, isn't? Seems not very clean… (maybe it's still the best idea)

[Laurent]

But it's a bit weird to do a binding from another binding, isn't? Seems not very clean…

C has a standard ABI (binary interface), C++ doesn't. Therefore is it common that bindings require an intermediate C binding; not all languages support being linked to C++ directly.

In fact SWIG will probably generate this intermediate C binding automatically for languages that can't link to C++.

[Dragnalith]

In fact SWIG will probably generate this intermediate C binding automatically for languages that can't link to C++.

Yes that's true. But SWIG will detect a class and bind it to go using interface and not giving the object struct pointer as first arguments.
Anyway, I'm sure the best is doing it by hand. I will try.

[Dragnalith]

I begin to bind some function, just the Window functions for testing.
But I have an error Cannot create a window from a worker thread. (OS X limitation). I sure is because of the thread go use for his runtime. But that mean on Mac OS X the binding can be hard to do because I can't force Go to execute my app in the main thread.

[daemon]

I wrote Go bindings some time ago in order to get familiar with Go. Maybe you'd like to check out my repository.
Binding: https://bitbucket.org/krepa098/gosfml2
Samples: https://bitbucket.org/krepa098/gosfml2-samples
I'm not sure whether I did it right as I'm quite new to the Go language, but at least it seems to work. 

[Dragnalith]

That's great! I'm also new on Go universe, so I don't know either if my binding would follow the right convention. I check out your work, is really great. Did you write it by hand or is it generated?
You follow the same convention as me, so I like it!

[daemon]

Yes it's all handwritten (with a lot of copy-pasting involved). Do you actually cast Go-structs to C, like in toCPtr()? I don't think it's safe because the compiler could decide to add padding.  Any ideas?

[Dragnalith]

No… I guess it's possible but I didn't find any document for Go to C. But where do you need to cast Go struct to C ?

[daemon]

I was actually referring to this file (line 44). I know that I can work around it but I'm not sure if I really have to. Anyway, the bindings should be almost complete by now.

[Dragnalith]

I don't find a way to do that. But you can convert it to a C.Rectf, then copy the four attribute.

[gyscos]

It really looks great, and I'm eager to try it - but how do you build the library ?

I "go get"ed it, but when I try go build I get these errors :
1: error: 'sfJoystickConnectEvent' undeclared (first use in this function)
... and 8 other similar errors, with other Event types.

I have the last SFML sources (from 2012-11-24) ; is this a problem ? Do I need to put them somewhere specific ?

EDIT : just noticed I also might need csfml. I have version 1.99 from 2012-05-04. Is it too old ?
EDIT2 : Ow, grabbed csfml from git, and it works ! Quite impressive...

[daemon]

I'm trying to keep up with SFML git. That's why you need the latest version of SFML and CSFML. I hope you'll enjoy it. Feedback is welcome. 

[gyscos]

The lack of any good gui or graphic library for go really turned me down, so finding this was quite exciting. As soon as I finish the mandatory tetris clone, I'll try some fun thing and let you know how gosfml goes