Delphi/Free Pascal OpenGL Header for OpenGL 4.4a - Readme -

Description

This is the readme for the OpenGL-Headers for Delphi/FreePascal that has been developed by DGL's OpenGL2.0-Portteam. Please read carefully through this file before using the header to avoid common problems and faults. The changelog is included in the source file itself.

How to use

Before you can use any of the gl-functions contained in the header, you'll have to call InitOpenGL to initialize the functionpointers. In your app it should look something like that :

procedure MyGLInit;
begin
  InitOpenGL; // Don't forget, or first gl-Call will result in an access violation!
  MyDC := GetDC(...);
  MyRC := CreateRenderingContext(...);
  ActivateRenderingContext(MyDC, MyRC); // Necessary, will also read some extension
  ...
end;

After doing the above initialisation, you're ready to use all OpenGL-Functions and extensions your card supports. And also don't forget to release your context properly when exiting :

procedure MyDeInit;
begin
  DeactivateRenderingContext; // Deactivates the current context
  wglDeleteContext(myRC);
  ReleaseDC(Handle, myDC);
end;

Creating a versioned rendering context

As of OpenGL version 4.4, the header offers an additional way of creating a rendercontext, that allows for setting the desired OpenGL version and (if applicable) wether to create a forward compatible context (see OpenGL man pages on what that means) :

procedure MyGLInit;
begin
  DC := GetDC(...);
  RC := CreateRenderingContextVersion(DC, [opDoubleBuffered], 4, 2, True, 32, 24, 8, 0, 0, 0); // Creates an OpenGL 4.2 forward-compatible context
  InitOpenGL; // Don't forget, or first gl-Call will result in an access violation!
  ...
end;

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