OpenGL快速闪烁问题-现在不显示图像 [英] OpenGL Rapid Flickering Issues - and now not showing image
问题描述
我在OpenGL上遇到了一些麻烦.首先，我要构建一个自定义控件，该控件封装了OpenGL.我遇到了一个快速闪烁的问题，就像它在闪烁"一样.该控件太大且太复杂，无法在此处发布，因此我制作了一个新的小型演示应用程序来演示和重新创建相同的场景.
I'm having some troubles with OpenGL. First of all, I have a custom control which I'm building, encapsulating OpenGL. I'm having a problem where it rapidly flickers, like it's 'flashing'. The control was too large and complex to post here, so I made a new small demo app to demonstrate and recreate the same scenario.
现在的问题:我没有得到任何图像.一切在我的自定义控件中都可以很好地显示，但是由于我已经复制了代码并将其剥离到一个小型演示应用程序中，因此它不会显示图像.因此，这里有两个问题:闪烁(或闪烁)，现在图像甚至没有显示.以前没有发生闪烁，但是在进行了一些重大的代码修订后，它开始闪烁.太多的代码更改无法解释到底发生了什么更改，几乎所有内容.
The problem now: I'm not getting any image. Things would show fine in my custom control, but since I've copied the code and stripped it down in a small demo app, it won't show the image. So here I have two issues at hand: Flickering (or flashing), and now the image is not even showing. The flickering didn't occur in the past, but after some major code revision, it started flickering. It was too much code change to explain what exactly was changed, just about everything.
背景显示，所以我知道它正在绘制某些东西(它是彩色的).出于演示目的，它应该只绘制一个多维数据集，但我什么也看不到.我不得不将其从大约1000行代码缩减到甚至300行.
The background shows, so I know it's drawing something (it is colored). It should be drawing just a single cube for demo purposes, but I don't see anything. I had to strip this down from around 1,000 lines of code to not even 300.
这不是通常所说的闪烁"，实际上更多的是闪烁，或者闪烁，想象一下汽车方向盘闪烁着.绝对与计时器有关，因为我设定的计时器间隔越大，闪烁的速度就越慢.
It's not what you would normally call a flicker, it's actually more of a flashing, or blinking, imagine a car blinker flashing on and off. It definitely has to do with the timer, because the higher interval I put on the timer, the slower it flashes.
为什么我什么都没看到?一旦解决，为什么它会闪烁这么多?
Why am I not seeing anything? And once this is fixed, why is it flickering so much?
这是单个表单的代码，无需DFM:
Here's a single form's code, no DFM necessary:
unit uMain;
interface
uses
Winapi.Windows, Winapi.Messages, Winapi.OpenGL,
System.SysUtils, System.Variants, System.Classes,
Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ExtCtrls;
type
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure Timer1Timer(Sender: TObject);
procedure FormResize(Sender: TObject);
private
FDrawing: Bool;
FDC: HDC;
FRC: HGLRC;
FDL: glUint;
FTimer: TTimer;
procedure Draw;
procedure SetDC(const Value: HDC);
procedure SetRC(const Value: HGLRC);
procedure SetDL(const Value: glUint);
public
property DC: HDC read FDC write SetDC;
property RC: HGLRC read FRC write SetRC;
property DL: glUint read FDL write SetDL;
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.FormCreate(Sender: TObject);
var
PixelFormat: glUint;
pfd: TPIXELFORMATDESCRIPTOR;
begin
FDrawing := False;
FDC := GetDC(Handle);
with pfd do begin
nSize := SizeOf(TPIXELFORMATDESCRIPTOR);
nVersion := 1; // The version of this data structure
dwFlags := PFD_DRAW_TO_WINDOW // Buffer supports drawing to window
or PFD_SUPPORT_OPENGL // Buffer supports OpenGL drawing
or PFD_DOUBLEBUFFER; // Supports double buffering
iPixelType := PFD_TYPE_RGBA; // RGBA color format
cColorBits := 32; // OpenGL color depth
cRedBits := 0; // Number of red bitplanes
cRedShift := 0; // Shift count for red bitplanes
cGreenBits := 0; // Number of green bitplanes
cGreenShift := 0; // Shift count for green bitplanes
cBlueBits := 0; // Number of blue bitplanes
cBlueShift := 0; // Shift count for blue bitplanes
cAlphaBits := 0; // Not supported
cAlphaShift := 0; // Not supported
cAccumBits := 0; // No accumulation buffer
cAccumRedBits := 0; // Number of red bits in a-buffer
cAccumGreenBits := 0; // Number of green bits in a-buffer
cAccumBlueBits := 0; // Number of blue bits in a-buffer
cAccumAlphaBits := 0; // Number of alpha bits in a-buffer
cDepthBits := 16; // Specifies the depth of the depth buffer
cStencilBits := 0; // Turn off stencil buffer
cAuxBuffers := 0; // Not supported
iLayerType := PFD_MAIN_PLANE; // Ignored
bReserved := 0; // Number of overlay and underlay planes
dwLayerMask := 0; // Ignored
dwVisibleMask := 0; // Transparent color of underlay plane
dwDamageMask := 0; // Ignored
end;
PixelFormat := ChoosePixelFormat(FDC, @pfd);
SetPixelFormat(FDC, PixelFormat, @pfd);
FRC := wglCreateContext(FDC);
wglMakeCurrent(FDC, FRC);
FormResize(nil);
wglMakeCurrent(FDC, FRC);
glClearColor(0.8, 0.8, 0.9, 0.0);
glShadeModel(GL_FLAT);
glClearDepth(1.0);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
glEnable(GL_ALPHA_TEST);
glAlphaFunc(GL_GREATER, 0.4);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_BLEND);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
glEnable(GL_TEXTURE_2D);
glNewList(FDL, GL_COMPILE);
glBegin(GL_QUADS);
// Front Face
glTexCoord2f(0.0, 0.0);
glVertex3f(-2.0, -1.0, 1.0);
glTexCoord2f(2.0, 0.0);
glVertex3f(2.0, -1.0, 1.0);
glTexCoord2f(2.0, 1.0);
glVertex3f(2.0, 1.0, 1.0);
glTexCoord2f(0.0, 1.0);
glVertex3f(-2.0, 1.0, 1.0);
// Back Face
glTexCoord2f(2.0, 0.0);
glVertex3f(-2.0, -1.0, -1.0);
glTexCoord2f(2.0, 1.0);
glVertex3f(-2.0, 1.0, -1.0);
glTexCoord2f(0.0, 1.0);
glVertex3f(2.0, 1.0, -1.0);
glTexCoord2f(0.0, 0.0);
glVertex3f(2.0, -1.0, -1.0);
// Top Face
glTexCoord2f(0.0, 1.0);
glVertex3f(-2.0, 1.0, -1.0);
glTexCoord2f(0.0, 0.0);
glVertex3f(-2.0, 1.0, 1.0);
glTexCoord2f(2.0, 0.0);
glVertex3f(2.0, 1.0, 1.0);
glTexCoord2f(2.0, 1.0);
glVertex3f(2.0, 1.0, -1.0);
// Bottom Face
glTexCoord2f(2.0, 1.0);
glVertex3f(-2.0, -1.0, -1.0);
glTexCoord2f(0.0, 1.0);
glVertex3f(2.0, -1.0, -1.0);
glTexCoord2f(0.0, 0.0);
glVertex3f(2.0, -1.0, 1.0);
glTexCoord2f(2.0, 0.0);
glVertex3f(-2.0, -1.0, 1.0);
// Left Face
glTexCoord2f(0.0, 0.0);
glVertex3f(2.0, -1.0, -1.0);
glTexCoord2f(1.0, 0.0);
glVertex3f(2.0, -1.0, 1.0);
glTexCoord2f(1.0, 1.0);
glVertex3f(2.0, 1.0, 1.0);
glTexCoord2f(0.0, 1.0);
glVertex3f(2.0, 1.0, -1.0);
glEnd();
glEndList();
FTimer:= TTimer.Create(nil);
FTimer.OnTimer:= Timer1Timer;
FTimer.Interval:= 100;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
FTimer.Free;
if (not wglMakeCurrent(FDC, 0)) then
MessageBox(0, 'Release of DC and RC failed!', 'Error', MB_OK or MB_ICONERROR);
if (not wglDeleteContext(FRC)) then begin
MessageBox(0, 'Release of rendering context failed!', 'Error', MB_OK or MB_ICONERROR);
FRC := 0;
end;
if ((FDC > 0) and (ReleaseDC(Handle, FDC) = 0)) then begin
MessageBox(0, 'Release of device context failed!', 'Error', MB_OK or MB_ICONERROR);
FDC := 0;
end;
end;
procedure TForm1.Draw;
var
I: Integer;
begin
if not FDrawing then begin
FDrawing := TRUE;
try
glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);
glEnable(GL_NORMALIZE);
glShadeModel(GL_FLAT);
glCullFace(GL_BACK);
glLoadIdentity;
glPushMatrix();
glCallList(DL);
glPopMatrix();
SwapBuffers(wglGetCurrentDC);
finally
FDrawing := False;
end;
end;
end;
procedure TForm1.FormResize(Sender: TObject);
begin
glViewport(0, 0, Width, Height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0, Width / Height, 0.1, 500.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
end;
procedure TForm1.SetDC(const Value: HDC);
begin
FDC := Value;
end;
procedure TForm1.SetDL(const Value: glUint);
begin
FDL := Value;
end;
procedure TForm1.SetRC(const Value: HGLRC);
begin
FRC := Value;
end;
procedure TForm1.Timer1Timer(Sender: TObject);
begin
Draw;
end;
end.
现在上面的代码与我的原始代码的工作方式有很大不同.原始的Draw过程通过对象列表进行迭代，每个对象都包含其自己的Draw过程.因此，控件的绘制过程将准备整个场景，然后依次绘制每个项目"，如下所示:
Now the above code is rather far different from how my original code works. The original Draw procedure does an iteration through a list of objects, each object containing its own Draw procedure. So the control's draw procedure prepares the overall scene, then draws each 'item' one by one, like this:
procedure TGLImage.Draw;
var
X: Integer;
begin
if not FDrawing then begin
FDrawing := TRUE;
try
glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);
glEnable(GL_NORMALIZE);
glShadeModel(GL_FLAT);
glCullFace(GL_BACK);
glLoadIdentity();
glRotatef(FElapsedTime / 70, 0, 0, 1);
glRotatef(90, 0, 1, 0);
glTranslatef(-FElapsedTime / 400, 0, 0);
if FInitialized then begin
for X := 0 to FItems.Count - 1 do begin
FItems[X].Draw;
end;
end;
SwapBuffers(wglGetCurrentDC);
finally
FDrawing := False;
end;
end;
end;
这是它绘制的项目之一...
And here's one of the items it draws...
constructor TGLBeam.Create(AOwner: TGLItems);
begin
inherited;
glNewList(DL, GL_COMPILE);
glBegin(GL_QUADS);
// Front Face
glTexCoord2f(0.0, 0.0);
glVertex3f(-2.0, -1.0, 1.0);
glTexCoord2f(2.0, 0.0);
glVertex3f(2.0, -1.0, 1.0);
glTexCoord2f(2.0, 1.0);
glVertex3f(2.0, 1.0, 1.0);
glTexCoord2f(0.0, 1.0);
glVertex3f(-2.0, 1.0, 1.0);
// Back Face
glTexCoord2f(2.0, 0.0);
glVertex3f(-2.0, -1.0, -1.0);
glTexCoord2f(2.0, 1.0);
glVertex3f(-2.0, 1.0, -1.0);
glTexCoord2f(0.0, 1.0);
glVertex3f(2.0, 1.0, -1.0);
glTexCoord2f(0.0, 0.0);
glVertex3f(2.0, -1.0, -1.0);
// Top Face
glTexCoord2f(0.0, 1.0);
glVertex3f(-2.0, 1.0, -1.0);
glTexCoord2f(0.0, 0.0);
glVertex3f(-2.0, 1.0, 1.0);
glTexCoord2f(2.0, 0.0);
glVertex3f(2.0, 1.0, 1.0);
glTexCoord2f(2.0, 1.0);
glVertex3f(2.0, 1.0, -1.0);
// Bottom Face
glTexCoord2f(2.0, 1.0);
glVertex3f(-2.0, -1.0, -1.0);
glTexCoord2f(0.0, 1.0);
glVertex3f(2.0, -1.0, -1.0);
glTexCoord2f(0.0, 0.0);
glVertex3f(2.0, -1.0, 1.0);
glTexCoord2f(2.0, 0.0);
glVertex3f(-2.0, -1.0, 1.0);
// Left Face
glTexCoord2f(0.0, 0.0);
glVertex3f(2.0, -1.0, -1.0);
glTexCoord2f(1.0, 0.0);
glVertex3f(2.0, -1.0, 1.0);
glTexCoord2f(1.0, 1.0);
glVertex3f(2.0, 1.0, 1.0);
glTexCoord2f(0.0, 1.0);
glVertex3f(2.0, 1.0, -1.0);
glEnd();
glEndList();
end;
procedure TGLBeam.Draw;
var
I: Integer;
begin
glRotatef(Directions.X, 1.0, 0.0, 0.0);
glRotatef(Directions.Y, 0.0, 1.0, 0.0);
glRotatef(Directions.Z, 0.0, 0.0, 1.0);
for I := 1 to 10 do begin
//Main Center
glPushMatrix();
glTranslatef(I * 4 + Owner.Owner.ClockTime * 4, 0, 0);
glCallList(DL);
glPopMatrix();
//Above
glPushMatrix();
glTranslatef(I * 4 + Owner.Owner.ClockTime * 4, 6, 0);
glCallList(DL);
glPopMatrix();
end;
end;
推荐答案
已经发现了闪烁的问题，这是一个非常大的错误，我不希望您在没有整个项目的情况下就发现了.问题是我正在创建两个这些控件，并且它们相互干扰/斗争.实际上，由于OpenGL是在逐个线程的基础上(或在一个上下文"中)工作，因此拥有两个试图绘制自己的图形的不同控件将产生干扰-导致同一事件同时在两个控件上发生.因此，闪烁是由于每个控件都试图轮流进行绘制.我提出的与将该图形放入Thread有关的新问题将完全解决此问题.这是一个愚蠢的错误，很抱歉浪费任何人的时间.
The issue with the flickering was has been discovered, and it was a very huge mistake that I don't expect you to have figured out without having the entire project. The problem was that I was creating TWO of these controls, and they were interfering / fighting with each other. Actually, because OpenGL works on a thread-by-thread basis (or within one 'context'), having two different controls which are trying to do their own drawing will interfere - causing the same thing to occur on both controls at the same time. So the flashing was from the fact that each control was trying to take turns doing the drawing. My new question which I have asked related to putting this drawing inside of a Thread will perfectly cure for this issue. It was a dumb mistake and I'm sorry for wasting anyone's time.
这篇关于OpenGL快速闪烁问题-现在不显示图像的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
