wxWidgets中简单的openGL显示循环期间不完整的场景重绘答案

【问题标题】：incomplete scene redrawing during simple openGL display loop in wxWidgetswxWidgets中简单的openGL显示循环期间不完整的场景重绘
【发布时间】：2011-12-27 10:05:44
【问题描述】：

我正在努力在 wxWidets openGl 应用程序中创建一个简单的动画循环。我有一个问题，循环迭代在每次迭代显示之前没有完全绘制屏幕。似乎 .1s 足以完全绘制简单的场景......谁能告诉我为什么它可能不会？

谢谢！

#include <wx/wx.h>
#include <wx/glcanvas.h>

#ifdef __WXMAC__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif

#ifndef WIN32
#include <unistd.h> // FIXME: ¿This work/necessary in Windows?
                    //Not necessary, but if it was, it needs to be replaced by process.h AND io.h
#endif

//#include "GlBox.cpp"

#include <iostream>
using namespace std;



class wxGLCanvasSubClass: public wxGLCanvas {

public:
    wxGLCanvasSubClass(wxFrame* parent);
    void Paintit(wxPaintEvent& event);
    void Render();
protected:
    DECLARE_EVENT_TABLE()

    //GlBox myBox; 
};

wxGLCanvasSubClass *thing;

static void timerRender(int count)
{
    thing->Render();
    cout << "render timeout was called \n";

    glutTimerFunc(25, timerRender, 0);

}

static void myIdleFunc()
{
     cout << "idleing \n";
     cout.flush();
}

static void setRender(wxGLCanvasSubClass *thing2)
{
    thing = thing2;
    cout << "global thing was set \n";

     glutTimerFunc(1100, timerRender, 0);
}

BEGIN_EVENT_TABLE(wxGLCanvasSubClass, wxGLCanvas)
    EVT_PAINT    (wxGLCanvasSubClass::Paintit)
END_EVENT_TABLE()

wxGLCanvasSubClass::wxGLCanvasSubClass(wxFrame *parent)
:wxGLCanvas(parent, wxID_ANY,  wxDefaultPosition, wxDefaultSize, 0, wxT("GLCanvas")){
    int argc = 1;
    char* argv[1] = { wxString((wxTheApp->argv)[0]).char_str() };

/*
NOTE: this example uses GLUT in order to have a free teapot model
to display, to show 3D capabilities. GLUT, however, seems to cause problems
on some systems. If you meet problems, first try commenting out glutInit(),
then try comeenting out all glut code
*/
    glutInit(&argc, argv);

    glutIdleFunc(myIdleFunc);
}


void wxGLCanvasSubClass::Paintit(wxPaintEvent& WXUNUSED(event)){
    Render();
}

void wxGLCanvasSubClass::Render()
{
    SetCurrent();
    wxPaintDC(this);
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glClear(GL_COLOR_BUFFER_BIT);
    glViewport(0, 0, (GLint)GetSize().x, (GLint)GetSize().y);

    glBegin(GL_POLYGON);
        glColor3f(1.0, 1.0, 1.0);
        glVertex2f(-0.5, -0.5);
        glVertex2f(-0.5, 0.5);
        glVertex2f(0.5, 0.5);
        glVertex2f(0.5, -0.5);
        glColor3f(0.4, 0.5, 0.4);
        glVertex2f(0.0, -0.8);
    glEnd();



// using a little of glut
    glColor4f(0,0,1,1);
    glutWireTeapot(0.4);

    glLoadIdentity();
    glColor4f(2,0,1,1);
    glutWireTeapot(0.6);

    //myBox.getIt();


    SwapBuffers();
    glFlush();
    //

}




class MyApp: public wxApp
{
    virtual bool OnInit();

    void onIdle(wxIdleEvent& evt);

    time_t lastEvent;  
    bool slept ;

    wxGLCanvas * MyGLCanvas;
    wxGLCanvasSubClass * myCanvas;
};


IMPLEMENT_APP(MyApp)


bool MyApp::OnInit()
{
    slept = false;
    lastEvent = time( &lastEvent);
    wxFrame *frame = new wxFrame((wxFrame *)NULL, -1,  wxT("Hello GL World"), wxPoint(50,50), wxSize(200,200));
    myCanvas = new wxGLCanvasSubClass(frame);

    frame->Show(TRUE);

    Connect( wxID_ANY, wxEVT_IDLE, wxIdleEventHandler(MyApp::onIdle) );

    return TRUE;
}

void MyApp::onIdle(wxIdleEvent& evt)
{

    if(slept)
    {
        slept = false;
        cout << "event hit " << lastEvent;
        myCanvas->Render();
        evt.RequestMore();

    } else {
        cout << "idleing \n " << lastEvent;
        usleep(100000);
        slept = true;
        evt.RequestMore();  

    }

}

【问题讨论】：

选择一个框架。 wxWidgets 和 GLUT 都想控制你的事件循环。

标签： c++ opengl wxwidgets

【解决方案1】：

对于 OpenGL，GLUT 并不是必须使用的。 GLUT 是第三方框架，wxWidgets 是第三方框架。并且都实现了一个事件循环。

你不应该混合这些。只使用 wxWidgets，它提供了一个非常好的 OpenGL 小部件。

【讨论】：