wxWidgets中OpenGL渲染环境的配置，主要解决不能显示物体阴影问题

在使用wxWidgets图形库之前，一直在使用GLUT库来为OpenGL程序提供图形界面，但其毕竟只能算是一个中间过渡，想要有更完整的图形的库，那么选择之一便是wxWidgets库。

目前本人所使用的wxWidgets版本号是"wxWidgets-3.0.2",想要有使用其它版本，请参考官网。

下面主要分享一下在wxCanvas中如何设置OpenGL渲染上下文，解决物体阴影不能显示的问题，给出一个wxGLCanvas初始化的例子。

直接上代码：

1.头文件main.h

#include "wx/wx.h"#include "wx/glcanvas.h"class BasicGLPane : public wxGLCanvas{wxGLContext*m_context;public:BasicGLPane(wxFrame* parent, int* args);virtual ~BasicGLPane();void resized(wxSizeEvent& evt);int getWidth();int getHeight();void render(wxPaintEvent& evt);void prepare3DViewport(int topleft_x, int topleft_y, int bottomrigth_x, int bottomrigth_y);// eventsvoid mouseMoved(wxMouseEvent& event);void mouseDown(wxMouseEvent& event);void mouseWheelMoved(wxMouseEvent& event);void mouseReleased(wxMouseEvent& event);void rightClick(wxMouseEvent& event);void mouseLeftWindow(wxMouseEvent& event);void keyPressed(wxKeyEvent& event);void keyReleased(wxKeyEvent& event);DECLARE_EVENT_TABLE()};#endif

2.cpp文件main.cpp

#include <gl\glew.h>#include "wx/wx.h"#include "wx/sizer.h"#include "wx/glcanvas.h"#include "main.h"#include "shadowGenerator.h"// include OpenGL#ifdef __WXMAC__#include "OpenGL/glu.h"#include "OpenGL/gl.h"#else#include <GL/glu.h>#include <GL/gl.h>#endifclass MyApp : public wxApp{virtual bool OnInit();wxFrame *frame;BasicGLPane * glPane;public:};IMPLEMENT_APP(MyApp)bool MyApp::OnInit(){//wxBoxSizer* sizer = new wxBoxSizer(wxHORIZONTAL);frame = new wxFrame((wxFrame *)NULL, -1, wxT("Hello GL World"), wxPoint(50, 50), wxSize(400, 400));<span style="color:#000099;"><span style="white-space:pre"></span>//很重要的一个参数集，下面正文会有讲到int args[] = { WX_GL_RGBA, WX_GL_DOUBLEBUFFER, WX_GL_DEPTH_SIZE, 32, 0 };</span>glPane = new BasicGLPane((wxFrame*)frame, args);//sizer->Add(glPane, 1, wxEXPAND);//frame->SetSizer(sizer);//frame->SetAutoLayout(true);frame->Show();InitGLObjects();return true;}BEGIN_EVENT_TABLE(BasicGLPane, wxGLCanvas)EVT_MOTION(BasicGLPane::mouseMoved)EVT_LEFT_DOWN(BasicGLPane::mouseDown)EVT_LEFT_UP(BasicGLPane::mouseReleased)EVT_RIGHT_DOWN(BasicGLPane::rightClick)EVT_LEAVE_WINDOW(BasicGLPane::mouseLeftWindow)EVT_SIZE(BasicGLPane::resized)EVT_KEY_DOWN(BasicGLPane::keyPressed)EVT_KEY_UP(BasicGLPane::keyReleased)EVT_MOUSEWHEEL(BasicGLPane::mouseWheelMoved)EVT_PAINT(BasicGLPane::render)END_EVENT_TABLE()// some useful events to usevoid BasicGLPane::mouseMoved(wxMouseEvent& event) {}void BasicGLPane::mouseDown(wxMouseEvent& event) {}void BasicGLPane::mouseWheelMoved(wxMouseEvent& event) {}void BasicGLPane::mouseReleased(wxMouseEvent& event) {}void BasicGLPane::rightClick(wxMouseEvent& event) {}void BasicGLPane::mouseLeftWindow(wxMouseEvent& event) {}void BasicGLPane::keyPressed(wxKeyEvent& event) {}void BasicGLPane::keyReleased(wxKeyEvent& event) {}BasicGLPane::BasicGLPane(wxFrame* parent, int* args) :wxGLCanvas(parent, wxID_ANY, args, wxDefaultPosition, wxDefaultSize, wxFULL_REPAINT_ON_RESIZE){

m_context = new wxGLContext(this);// To avoid flashing on MSW

<span style="color:#000099;"><span style="white-space: pre;"></span>//原文上设置为，wxBG_STYLE_CUSTOM，但是在这个版本中，已声明为predicated,请使用wxBG_STYLE_PAIT</span>SetBackgroundStyle(wxBG_STYLE_PAINT);

<span style="white-space:pre"></span>

<span style="white-space:pre"></span>//SetCurrent( ),默许设置，还是算了。SetCurrent(*m_context);if (glewInit() != GLEW_OK){int i = 0;}}BasicGLPane::~BasicGLPane(){delete m_context;}void BasicGLPane::resized(wxSizeEvent& evt){wxGLCanvas::OnSize(evt);//if (getHeight()== 0)//h = 1;glViewport(0.0, 0.0, getWidth(), getHeight());glMatrixMode(GL_PROJECTION);glLoadIdentity();gluPerspective(45.0, (GLdouble)getWidth() / getHeight(), 0.01f, 100.0f);glMatrixMode(GL_MODELVIEW);glLoadIdentity();gluLookAt(0.0f, 0.0, 10.0f, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0f);//Refresh();                     //取消注释，则在本人电脑上会出现闪烁的问题}/** Inits the OpenGL viewport for drawing in 3D. */void BasicGLPane::prepare3DViewport(int topleft_x, int topleft_y, int bottomrigth_x, int bottomrigth_y){glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Black BackgroundglClearDepth(1.0f);// Depth Buffer SetupglEnable(GL_DEPTH_TEST); // Enables Depth TestingglDepthFunc(GL_LEQUAL); // The Type Of Depth Testing To DoglHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);//glEnable(GL_COLOR_MATERIAL);glViewport(topleft_x, topleft_y, bottomrigth_x - topleft_x, bottomrigth_y - topleft_y);glMatrixMode(GL_PROJECTION);glLoadIdentity();float ratio_w_h = (float)(bottomrigth_x - topleft_x) / (float)(bottomrigth_y - topleft_y);gluPerspective(45 /*view angle*/, ratio_w_h, 0.1 /*clip close*/, 100 /*clip far*/);glMatrixMode(GL_MODELVIEW);glLoadIdentity();}int BasicGLPane::getWidth(){return GetSize().x;}int BasicGLPane::getHeight(){return GetSize().y;}void BasicGLPane::render(wxPaintEvent& evt){if (!IsShown()) return;wxGLCanvas::SetCurrent(*m_context);wxPaintDC(this); // only to be used in paint events. use wxClientDC to paint outside the paint eventglClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);// ------------- draw some 3D ----------------prepare3DViewport(getWidth() / 2, 0, getWidth(), getHeight());glLoadIdentity();

<span style="white-space:pre"></span>//to draw something

SwapBuffers();}

程序中遇到的问题：

1、一开始想在wxWigets中也用GLUT来显示设备、显示模式等。

结论：愚拙的想法，外来人（GLUT）想来套近乎？只是“我”太高冷。

2、采用wxGLCanvas默认的上下文设置，即使用SetCurrent()，而非SetCurrent(*m_context)。

结论：SetCurrent():我不想梳妆打扮就去相亲。等我，Shadow。

    Shadow:         你太不符合我的胃口了，我也是有节操的，我是不会跟你一起的出现的。

    SetCurrent():真任性。我回去重新包装一下，看你还傲娇不。

3、定义一个窗体参数集 int args[] = { WX_GL_RGBA, WX_GL_DOUBLEBUFFER, WX_GL_DEPTH_SIZE,16 /*32*/, 0 };完成自定义风格的绘制设置。

结论：SetCurrent():Hi，Shadow我又来了，这次怎么样？

    Shadow:         你就想用16（深度缓冲精度）分的妆容来见我？

    SetCurrent():你还想我怎样？就配你还不够？

    Shadow:         就我吧，起码你得32分才可以。。（事实上，24就可以，毕竟傲娇嘛。）

    SetCurrent():我也是有原则的，最多24，给你，爱要不要。

    Shadow:       来吧，我们结婚吧。！！

小注：深度缓存的位数是衡量深度缓存精度的参数。深度缓存位数越高，则精确度越高，目前的显卡一般都可支持16位的Z       Buffer，一些高级的显卡已经可以支持32位的Z Buffer，但一般用24位Z Buffer就已经足够了。更加详细说明，请查       阅Z-BUFFER相关内容。

最后，基本上自己所用到的所有绘制功能都可以在这种配置上正确运行，但请不要忘了glewInit()的初始化，这个是必不可少的。

大家若是有其他更高的需求，请参考他人的文章。

PS：上面用到的代码示例，摘取自https://wiki.wxwidgets.org/WxGLCanvas。