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digitalmars.D.announce - glad OpenGL loader generator

reply David <d dav1d.de> writes:
glad - is an OpenGL loader (with experimental gles support, --api=gles2)
which is generated 1:1 from the OpenGL official spec
(https://cvs.khronos.org/svn/repos/ogl/trunk/doc/registry/public/api/gl.xml).
It has at the moment a "backend" for three languages (frontend parses,
backend generates code, like constants and function pointers).

https://github.com/Dav1dde/glad

What are the advantages over e.g. Derelict?

* supports *every* opengl extension
* always up to date
* (basically) never incorrect bindings
* easy to maintain
* easy API, 3 functions
* allows you to use your own loader

And the more important:
* provides an easy way to check if extension X is loaded
`enforce(GL_EXT_Cg_shader)` (same works for OpenGL versions
`enforce(GL_VERSION_3_2)`)
* glad generates loaders exactly for your needs. If you only need a
OpenGL 3.2 core profile with two extensions, glad can generate exactly
this code. Making your binding small, without overhead.


What your code might look like with glad:

import glad.gl; // imports all constants and functions, including extensions
import glad.loader : gladInit, gladTerminate, gladLoadGL;
void main() {
    gladInit();
    scope(exit) gladTerminate();

    /* setup OpenGL context with e.g. glfw */

    auto glv = gladLoadGL();
    enforce(glv.major == 3 && glv.minor == 2);
    // or: enforce(GL_VERSION_3_2);
    enforce(GL_EXT_texture_filter_anisotropic);

    /* done, use OpenGL here */
}

gladInit() and gladTerminate() are not needed if you provide your own
loader, e.g. you use SDL:

void main() {
    /* setup OpenGL context with SDL */

    auto glv = gladLoadGL(&SDL_GL_GetProcAddress);
    enforce(glv.major == 3 && glv.minor == 2);

    /* done, use OpenGL here */
}

A fully blown OpenGL 4.4 compatability, all extensions loader:
https://github.com/Dav1dde/glad/tree/d
But I really recommend generating your own loader/binding for your exact
needs!

python main.py --generator=d
--extensions=GL_EXT_texture_filter_anisotropic --out-path=build


A example in C:
https://github.com/Dav1dde/glad/blob/master/example/c/simple.c (to show
glad is not rocket science!)



------- Slightly Offtopic, why Derelict/Dynamic linking is bad  --------

glad was mainly written to have an easy backend to support multiple
languages at a time, but also to get rid of Derelict as a dependency.

(warn: dynamic/static linking "rant")

OpenGL was the only reason I still used Derelict, now I could get rid of
another relativly big dependency. Don't get me wrong Derelict is great,
but dynamic loading isn't! Unfortunatly you have to dynamically load OpenGL.

Why is dynamic loading a problem?
Well static linking has several important advantages:
* slightly faster startup times
* easier to distribute
* no DLL hell like on windows! with all it's DLLs, it's a mess!
https://en.wikipedia.org/wiki/DLL_hell

If you depend on a system-wide installation of a library you get another
problem Windows might have a different DLL than Ubuntu a .so  or
Archlinux or Debian old stable, so you have to ship your DLLs with you
or depend on a specific version, which makes distribution a lot harder.

You might say, but on Windows, I can't statically link because dmc
doesn't really work (e.g. Makefiles not supporting DM Make), objconv
(another dependency next to the C compiler) etc... Well on Windows you
can still use an import library. Which brings us to the next advantage.
You don't need two separate librarys for one and the same binding (one
which works like a C-Header and one with a ton of function pointers and
loader code attached).
Aug 05 2013
next sibling parent "w0rp" <devw0rp gmail.com> writes:
I'm glad you invested time in glad. I'll probably try it out soon 
enough.
Aug 05 2013
prev sibling next sibling parent reply Justin Whear <justin economicmodeling.com> writes:
It looks like your D backend generates string literals with literal null 
bytes--this is unnecessary as string literals are already null 
terminated. (Documented here: http://dlang.org/interfaceToC.html (see 
final bullet under "Call­ing C Func­tions")

Also, it looks like loading each extension requires scanning all 
available extension names, e.g. loading 25 extensions requires 25 linear 
scans of the extension list.  You might consider caching and sorting if 
the number of extensions requested is more than a handful.
Aug 05 2013
parent reply David <d dav1d.de> writes:
Am 06.08.2013 00:17, schrieb Justin Whear:

 It looks like your D backend generates string literals with literal null 
 bytes--this is unnecessary as string literals are already null 
 terminated. (Documented here: http://dlang.org/interfaceToC.html (see 
 final bullet under "Call­ing C Func­tions")


This is (was) on purpose.
I should probably change that now, since it will confuse people. I had
for a short time a mess in the generators and tried to use the D
generator to build for another language too, which required the explicit
\0 and .ptr


 Also, it looks like loading each extension requires scanning all 
 available extension names, e.g. loading 25 extensions requires 25 linear 
 scans of the extension list.  You might consider caching and sorting if 
 the number of extensions requested is more than a handful.


I was thinking of that, too, but caching the OpenGL call to
glGetStringi, I don't think you can prevent the linear searches.
Aug 05 2013
parent reply Justin Whear <justin economicmodeling.com> writes:
On Tue, 06 Aug 2013 00:21:46 +0200, David wrote:

 I was thinking of that, too, but caching the OpenGL call to
 glGetStringi, I don't think you can prevent the linear searches.


Why not something like this for the GL_VERSION >= 3 codepath in has_ext?
-----------------------------------
static auto availableExts;

if (availableExts.empty)
{
    int num;
    glGetIntegerv(GL_NUM_EXTENSIONS, &num);
    availableExts = new string[](num);

    foreach (i, ref extName; availableExts)
	extName = (cast(const(char)*)glGetStringi(GL_EXTENSIONS, i)).idup;

    availableExts.sort();
}

// Use binary search
return assumeSorted(availableExts).contains(ext);
-----------------------------------
Aug 05 2013
parent reply David <d dav1d.de> writes:
Am 06.08.2013 00:33, schrieb Justin Whear:

 On Tue, 06 Aug 2013 00:21:46 +0200, David wrote:

 I was thinking of that, too, but caching the OpenGL call to
 glGetStringi, I don't think you can prevent the linear searches.


 
 Why not something like this for the GL_VERSION >= 3 codepath in has_ext?
 -----------------------------------
 static auto availableExts;
 
 if (availableExts.empty)
 {
     int num;
     glGetIntegerv(GL_NUM_EXTENSIONS, &num);
     availableExts = new string[](num);
 
     foreach (i, ref extName; availableExts)
 	extName = (cast(const(char)*)glGetStringi(GL_EXTENSIONS, i)).idup;
 
     availableExts.sort();
 }
 
 // Use binary search
 return assumeSorted(availableExts).contains(ext);
 -----------------------------------
 


Thanks, I will definitly look into improving it (when I wake up ;))
Aug 05 2013
parent Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
On 8/6/13, David <d dav1d.de> wrote:

 Thanks, I will definitly look into improving it (when I wake up ;))


You should know better than to code when you're sleepwalking!

glad works great for me, I've tested it on Win7 x64. Great project!
Aug 05 2013
prev sibling next sibling parent reply "Land" <Land nospam.com> writes:
I really like the sound of this. I'll try it out tomorrow.
Aug 05 2013
parent reply David <d dav1d.de> writes:
Am 06.08.2013 01:11, schrieb Land:

 I really like the sound of this. I'll try it out tomorrow.


glad to hear that ;) (to join w0rp with glad jokes)
Aug 05 2013
parent Russel Winder <russel winder.org.uk> writes:
On Tue, 2013-08-06 at 02:00 +0200, David wrote:

 Am 06.08.2013 01:11, schrieb Land:

 I really like the sound of this. I'll try it out tomorrow.


=20
 glad to hear that ;) (to join w0rp with glad jokes)


I guess you will just have to play Cream's "I'm so glad" as a theme
tune.

--=20
Russel.
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D
Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder ekiga.n=
et
41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel winder.org.uk
London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder
Aug 06 2013
prev sibling next sibling parent reply David <d dav1d.de> writes:
I posted it also on reddit, maybe it draws some attention:
http://www.reddit.com/r/programming/comments/1jt9m5/multilanguage_opengl_loader_generator_based_on/
Aug 06 2013
parent reply David <d dav1d.de> writes:
Am 06.08.2013 16:32, schrieb David:

 I posted it also on reddit, maybe it draws some attention:
 http://www.reddit.com/r/programming/comments/1jt9m5/multilanguage_opengl_loader_generator_based_on/
 


Interesting it seems like it was deleted, but I don't know why?
... Ok
Aug 06 2013
parent "Mike Parker" <aldacron gmail.com> writes:
On Tuesday, 6 August 2013 at 16:47:52 UTC, David wrote:

 Am 06.08.2013 16:32, schrieb David:

 I posted it also on reddit, maybe it draws some attention:
 http://www.reddit.com/r/programming/comments/1jt9m5/multilanguage_opengl_loader_generator_based_on/
 


 Interesting it seems like it was deleted, but I don't know why?
 ... Ok


It's still there (also in /r/opengl). And the last comment was 2 
hours ago.
Aug 06 2013
prev sibling next sibling parent reply "evilrat" <evilrat666 gmail.com> writes:
On Monday, 5 August 2013 at 21:42:59 UTC, David wrote:

 glad - is an OpenGL loader (with experimental gles support, 
 --api=gles2)


...

i looked at this on github and see an option to build with gl3n, 
then i see what it is, and looks like gl3n is a 'must have' for 
my simple tasks. but for some reason it only builds with -m32 on 
OS X, i can't see where it puts this flag in makefile and why do 
the hell it inserts this. can you help explain how to get rid off 
this?
Aug 11 2013
parent reply David <d dav1d.de> writes:
Am 12.08.2013 07:06, schrieb evilrat:

 On Monday, 5 August 2013 at 21:42:59 UTC, David wrote:

 glad - is an OpenGL loader (with experimental gles support, --api=gles2)


 ...
 
 i looked at this on github and see an option to build with gl3n, then i
 see what it is, and looks like gl3n is a 'must have' for my simple
 tasks. but for some reason it only builds with -m32 on OS X, i can't see
 where it puts this flag in makefile and why do the hell it inserts this.
 can you help explain how to get rid off this?


Mh, there is no option to interact with gl3n, gl3n is completly
independent from glad/glamour/derelict.

Did you confuse gles2 (GL ES 2.0) with gl3n? Or did you speak of
glamour, which has indeed gl3n interaction, which can be turned on with
-version=gl3n: make DCFLAGS+="-version=gl3n".
But I recommend you to include gl3n and glamour as submodule or if you
don't use git, simply the sources. This makes your code independent of a
systemwide installation and it's only a few files.

glad is a replacement for Derelicts GL bindings. Soon it will also
provide a EGL support (which should already work), WGL and GLX.
Aug 12 2013
parent reply "evilrat" <evilrat666 gmail.com> writes:
On Monday, 12 August 2013 at 13:45:46 UTC, David wrote:

 Did you confuse gles2 (GL ES 2.0) with gl3n? Or did you speak of
 glamour, which has indeed gl3n interaction, which can be turned 
 on with
 -version=gl3n: make DCFLAGS+="-version=gl3n".
 But I recommend you to include gl3n and glamour as submodule or 
 if you
 don't use git, simply the sources. This makes your code 
 independent of a
 systemwide installation and it's only a few files.

 glad is a replacement for Derelicts GL bindings. Soon it will 
 also
 provide a EGL support (which should already work), WGL and GLX.


no no, i don't want use other opengl bindings right now, derelict 
just fine, but i need some good(public available) math lib to put 
in my examples, and the problem is that gl3n compiles as 32 
bit(-m32) on OS X(i use it because i don't have PC and i don't 
know when i would have it) by default and there seems no way to 
remove this misbehavior :(
Aug 12 2013
parent reply David <d dav1d.de> writes:
Am 13.08.2013 05:51, schrieb evilrat:

 On Monday, 12 August 2013 at 13:45:46 UTC, David wrote:

 Did you confuse gles2 (GL ES 2.0) with gl3n? Or did you speak of
 glamour, which has indeed gl3n interaction, which can be turned on with
 -version=gl3n: make DCFLAGS+="-version=gl3n".
 But I recommend you to include gl3n and glamour as submodule or if you
 don't use git, simply the sources. This makes your code independent of a
 systemwide installation and it's only a few files.

 glad is a replacement for Derelicts GL bindings. Soon it will also
 provide a EGL support (which should already work), WGL and GLX.


 
 no no, i don't want use other opengl bindings right now, derelict just
 fine, but i need some good(public available) math lib to put in my
 examples, and the problem is that gl3n compiles as 32 bit(-m32) on OS
 X(i use it because i don't have PC and i don't know when i would have
 it) by default and there seems no way to remove this misbehavior :(


This shouldn't happen and doesn't happen for me. Easiest way to use gl3n
(and also what I recommend) is to use it as git submodule or simply copy
the sources into your project and integrate it into your buildsystem.
Aug 13 2013
next sibling parent "evilrat" <evilrat666 gmail.com> writes:
On Tuesday, 13 August 2013 at 10:41:49 UTC, David wrote:

 This shouldn't happen and doesn't happen for me. Easiest way to 
 use gl3n
 (and also what I recommend) is to use it as git submodule or 
 simply copy
 the sources into your project and integrate it into your 
 buildsystem.


ok thanks, i'll try later.
Aug 13 2013
prev sibling parent "Brad Anderson" <eco gnuk.net> writes:
On Tuesday, 13 August 2013 at 10:41:49 UTC, David wrote:

 Am 13.08.2013 05:51, schrieb evilrat:

 On Monday, 12 August 2013 at 13:45:46 UTC, David wrote:

 Did you confuse gles2 (GL ES 2.0) with gl3n? Or did you speak 
 of
 glamour, which has indeed gl3n interaction, which can be 
 turned on with
 -version=gl3n: make DCFLAGS+="-version=gl3n".
 But I recommend you to include gl3n and glamour as submodule 
 or if you
 don't use git, simply the sources. This makes your code 
 independent of a
 systemwide installation and it's only a few files.

 glad is a replacement for Derelicts GL bindings. Soon it will 
 also
 provide a EGL support (which should already work), WGL and 
 GLX.


 
 no no, i don't want use other opengl bindings right now, 
 derelict just
 fine, but i need some good(public available) math lib to put 
 in my
 examples, and the problem is that gl3n compiles as 32 
 bit(-m32) on OS
 X(i use it because i don't have PC and i don't know when i 
 would have
 it) by default and there seems no way to remove this 
 misbehavior :(


 This shouldn't happen and doesn't happen for me. Easiest way to 
 use gl3n
 (and also what I recommend) is to use it as git submodule or 
 simply copy
 the sources into your project and integrate it into your 
 buildsystem.


Works well with dub. Dead simple too.
Aug 14 2013
prev sibling parent reply David <d dav1d.de> writes:
glad now supports also EGL, GLX and WGL
Aug 13 2013
parent David <d dav1d.de> writes:
Am 13.08.2013 19:38, schrieb David:

 glad now supports also EGL, GLX and WGL
 


You can add GLES to the list

TODO:
 * GLES loader
 * lazy loading
 * debugging (tracing function calls and error-checks with glGetError)
 * helperfunctions like gladGetErrorString(GLenum) or
gladEnumToString(GLenum) etc.
Aug 25 2013