[SOLVED] Problems with dglOpenGL on Windows
lazarus / 70-OpenGL

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soerensen3 · 2017-12-05 14:47

I have a problem with dglOpenGL on Windows. When I try to initialize
it doesn't find some of the functions. I am usually working on Linux,
where everything is working fine. It used to work on Windows as well
but for some reason it does not work anymore. I have an NVidia
discrete display adapter and an Intel adapter which supports GL up to
4.5 so it is not a hardware related issue.

This minimal example fails on Windows but works on Linux:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i program
Project1; uses dglOpenGL; begin  InitOpenGL();  ReadExtensions; 
WriteLn( Assigned( glGenerateMipmap )); // Returns False ..  it is not
the only function not working  ReadLn;end. 
I use Lazarus 1.8 RC 5 with FPC 3.0.4 (32 Bit) and the latest
dglOpenGL.pas.

Is it a drivers problem, maybe?

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marcov · 2017-12-05 14:56

Try in a lazarus app, maybe it only works with GUI apps.

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soerensen3 · 2017-12-05 15:08

That didn't help. Besides, I'm not talking about creating a context.
InitOpenGL/ReadExtensions just dynamically loads all the pointers to
the functions, which in my case does not work. I can however run other
programs using OpenGL. It might point to the wrong dll? According to
dependency walker "OpenGL32.dll" does indeed not have the functions I
was looking for.

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marcov · 2017-12-05 15:22

Well, my dglopengl apps initialize opengl the same way, but in a
lazarus application, and that works fine. Note to reach opengl3+
functions more is needed (see below)

opengl32.dll is afaik a windows DLL, but the driver must provide the
relevant implementation.

In the past the windows default driver was sometimes a shell, without
much 3d, but afaik that doesn't happen anymore since Windows 8.

My code is like:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i    if
FirstTime then   begin // used to do one time init stuff   
InitOpenGL;    ReadExtensions;  end;   OnResize := PanelResize; //
let's control our own resize, I have no idea which protected method is
below this so...  FBrightness := 10.0;   FDC := GetDC(Handle);  
pfd.nSize := SizeOf(pfd);  pfd.nVersion := 1;  pfd.dwFlags :=
PFD_DRAW_TO_WINDOW or PFD_SUPPORT_OPENGL or PFD_DOUBLEBUFFER; 
pfd.iPixelType := PFD_TYPE_RGBA;  pfd.cColorBits := 32;   pf :=
ChoosePixelFormat(FDC, @pfd);  b:=SetPixelFormat(FDC, pf, @pfd);   FRC
:= wglCreateContext(FDC);  b:=wglMakeCurrent(FDC, FRC);   if FirstTime
then begin // reread for opengl 3+ (?) properties.   
ReadImplementationProperties;    ReadExtensions;  end; 
b:=wglMakeCurrent(FDC, FRC);

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KemBill · 2017-12-05 15:51

Quote from: soerensen3 on December 05, 2017, 03:47:03 pmI have a
problem with dglOpenGL on Windows. When I try to initialize it doesn't
find some of the functions. I am usually working on Linux, where
everything is working fine. It used to work on Windows as well but for
some reason it does not work anymore. I have an NVidia discrete
display adapter and an Intel adapter which supports GL up to 4.5 so it
is not a hardware related issue.

This minimal example fails on Windows but works on Linux:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i program
Project1; uses dglOpenGL; begin  InitOpenGL();  ReadExtensions; 
WriteLn( Assigned( glGenerateMipmap )); // Returns False ..  it is not
the only function not working  ReadLn;end. 
I use Lazarus 1.8 RC 5 with FPC 3.0.4 (32 Bit) and the latest
dglOpenGL.pas.

Is it a drivers problem, maybe?

you miss ReadImplementationProperties after ReadExtensions; but
glGenerateMipmap  is loaded during the call of ReadExtensions

i'm in the same case, try :
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i WriteLn(
 dglCheckExtension('GL_ARB_framebuffer_object') );

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KemBill · 2017-12-05 16:51

this is related to the way you test. In a real window if i check for
extension GL_ARB_framebuffer_object, it's loaded

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soerensen3 · 2017-12-05 16:55

Thank you both! It works now!
The solution was to call ReadExtensions again after the Context is
initialized!
Quoteif FirstTime then begin // reread for opengl 3+ (?) properties.
    ReadImplementationProperties;
    ReadExtensions;
  end;

So the order is like this.
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
InitOpenGL();//CreateContextReadExtensions(); //Here the order does
not seem to matterReadImplementationProperties();//This might or might
not be necessary, I still have to find out what the procedure does
exactly

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Akira1364 · 2017-12-08 07:00

Your issue is likely related to the fact that there's no actual window
present, to be honest. OpenGL isn't a command-line API...