Help: OpenGL doesn't draw with OA

Help: OpenGL doesn't draw with OA

[Adrian B.Y. Hoe]

Hello:

I am learning/experimenting OpenGL with OA for windows 7.0 I could not
have a white square drawn on a blank window with black background.
Below is my code. Can someone show me the correct way to do it?
Also, can someone explain how the AuxReshapeFunc and AuxMainLoop
work?

Thanks in advance for your valuable time and effort.


Adrian


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with Win32.Gl;
with Win32.Glu;
with Win32.Glaux;
with Interfaces.C;
with Interfaces.C.Strings;
with System;
with Unchecked_Conversion;

use Win32.Gl;
use Win32.Glu;
use Win32.Glaux;
use Interfaces;

procedure TestOpenGL is

   function Conv is new Unchecked_Conversion (System.Address, AUXRESHAPEPROC);
   function Conv is new Unchecked_Conversion (System.Address, AUXMAINPROC);

   Window_Name : C.Char_Array := C.To_C("Test of OpenGL");
   Res         : Glenum;

   procedure MyInit;

   procedure Display;
   pragma Convention(Stdcall, Display);

   procedure MyInit is
   begin
      glClearColor(0.0, 0.0, 0.0, 0.0);
      glClear(GL_COLOR_BUFFER_BIT);
--      glColor3f(1.0, 1.0, 1.0);
--      glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
--      glBegin(GL_POLYGON);
--         glVertex3f(0.25, 0.25, 0.0);
--         glVertex3f(0.75, 0.25, 0.0);
--         glVertex3f(0.75, 0.75, 0.0);
--         glVertex3f(0.25, 0.75, 0.0);
--      glEnd;
--      glFlush;
   end MyInit;

   procedure Display is
   begin
      glColor3f(1.0, 1.0, 1.0);
      glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
      glBegin(GL_POLYGON);
         glVertex3f(0.25, 0.25, 0.0);
         glVertex3f(0.75, 0.25, 0.0);
         glVertex3f(0.75, 0.75, 0.0);
         glVertex3f(0.25, 0.75, 0.0);
      glEnd;
      glFlush;
   end Display;

begin
   AuxInitDisplayMode(AUX_SINGLE + AUX_RGB + AUX_DEPTH16);
   AuxInitPosition(0, 0, 400, 400);
   Res := AuxInitWindow(Window_Name(Window_Name'First)'Unchecked_Access);
   MyInit;
--   AuxReshapeFunc(Conv(MyReshape'Address));
   Auxmainloop(Conv(Display'Address));
end TestOpenGL;

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--

B.Y.

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 Adrian, B.Y. Hoe                     byHoe@quantum.pc.my           \/
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