Delphi OpenGL測試

Question

我在讀Delphi書的OpenGL開發指南，這段代碼應該設置窗口的背景顏色，但它不起作用，誰能告訴我什麼是錯？

type 
    TForm1 = class(TForm) 
     procedure Form_Create(Sender: TObject); 
    procedure Form_Destroy(Sender: TObject); 
    procedure FormPaint(Sender: TObject); 
     private 
     glContext : HGLRC; 
     glDC  : HDC; 
     errorCode : GLenum; 
     openGLReady : Boolean; 
     public 
    end; 

var 
    Form1 : TForm1; 

implementation 

{$R *.dfm} 

procedure TForm1.FormPaint(Sender: TObject); 
begin 
    if not openGLReady then 
     exit; 
    {background} 
    glClearColor(0.1,0.4,0.0,0.0); 
    glClear(GL_COLOR_BUFFER_BIT); 
    {error checking} 
    errorCode:=glGetError; 
    if errorCode<>GL_NO_ERROR then 
     raise Exception.Create('Error in Paint'#13+gluErrorString(errorCode)); 
end; 

procedure TForm1.Form_Create(Sender: TObject); 
var 
    pfd : TPixelFormatDescriptor; 
    FormatIndex: integer; 
begin 
    fillchar(pfd,SizeOf(pfd),0); 
    with pfd do 
    begin 
     nSize := SizeOf(pfd); 
     nVersion := 1; {The current version of the desccriptor is 1} 
     dwFlags := PFD_DRAW_TO_WINDOW or PFD_SUPPORT_OPENGL; 
     iPixelType := PFD_TYPE_RGBA; 
     cColorBits := 24; {support 24-bit color} 
     cDepthBits := 32; {depth of z-axis} 
     iLayerType := PFD_MAIN_PLANE; 
    end; {with} 
    glDC := getDC(handle); 
    FormatIndex := ChoosePixelFormat(glDC,@pfd); 
    if FormatIndex=0 then 
     raise Exception.Create('ChoosePixelFormat failed '+IntToStr(GetLastError)); 
    if not SetPixelFormat(glDC,FormatIndex,@pfd) then 
     raise Exception.Create('SetPixelFormat failed '+IntToStr(GetLastError)); 
    GLContext := wglCreateContext(glDC); 
    if GLContext=0 then 
     raise Exception.Create('wglCreateContext failed '+IntToStr(GetLastError)); 
    if not wglMakeCurrent(glDC,GLContext) then 
     raise Exception.Create('wglMakeCurrent failed '+IntToStr(GetLastError)); 
    OpenGLReady := true; 
end; 

procedure TForm1.Form_Destroy(Sender: TObject); 
begin 
    wglMakeCurrent(Canvas.Handle, 0); 
    wglDeleteContext(GLContext); 
end; 

Answer 1

添加在程序FormPaint的OpenGL命令的末尾：

glFlush(); 

Answer 2

swapbuffers(gldc); 

？