请各位大侠教我用opengl画个圆吧！！！

Question

看了一阵子书连个圆都不知道怎么画，最好给个DELPHI下面的例子，特谢！！！

Answer 1

unit MainFrm;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, OpenGL;type
  TfrmMain = class(TForm)
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure FormPaint(Sender: TObject);
    procedure FormResize(Sender: TObject);
  private
    { Private declarations }
    hrc:HGLRC;
    w,h:glFloat;
    Sphere:GLUquadricObj;
  public
    { Public declarations }
    procedure MyDraw;
  end;var
  frmMain: TfrmMain;implementation{$R *.dfm}procedure TfrmMain.FormCreate(Sender: TObject);
var
  pfd:TPixelFormatDescriptor;
  PixelFormat:Integer;
begin
  ControlStyle:=ControlStyle+[csOpaque];
  FillChar(pfd,sizeof(pfd),0);
  with pfd do
  begin
    nSize:=sizeof(TPixelFormatDescriptor);
    nVersion:=1;
    dwFlags:=PFD_DRAW_TO_WINDOW or
        PFD_SUPPORT_OPENGL or PFD_DOUBLEBUFFER;
    iPixelType:=PFD_TYPE_RGBA;
    cColorBits:=24;
    cDepthBits:=32;
    iLayerType:=PFD_MAIN_PLANE;
  end;
  PixelFormat:=ChoosePixelFormat(Canvas.Handle,@pfd);
  SetPixelFormat(Canvas.Handle,PixelFormat,@pfd);
  hrc:=wglCreateContext(Canvas.Handle);
  w:=ClientWidth;
  h:=ClientHeight;
end;procedure TfrmMain.FormDestroy(Sender: TObject);
begin
  wglDeleteContext(hrc);
end;procedure TfrmMain.FormPaint(Sender: TObject);
begin
  wglMakeCurrent(Canvas.Handle,hrc);
  glClearColor(1,1,1,1);
  glColor3f(1,0,0);
  glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);
  MyDraw;
  glFlush;
  SwapBuffers(Canvas.Handle);
end;procedure TfrmMain.MyDraw;
begin
  glPushMatrix;
  Sphere:=gluNewQuadric;
  gluQuadricDrawStyle(Sphere,GLU_LINE);
  gluSphere(Sphere,0.5,25,25);
  glPopMatrix;
  SwapBuffers(Canvas.handle);
  gluDeleteQuadric(Sphere);
end;procedure TfrmMain.FormResize(Sender: TObject);
begin
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity;
  glFrustum(-1.0,1.0,-1.0,1.0,3.0,7.0);
  glViewPort(0,0,ClientWidth,ClientHeight);
  MyDraw;
end;end.