GLView是cocos2d-x基于OpenGL ES的调用封装UI库。
OpenGL本身是跨平台的计算机图形实现API，在每一个平台的详细实现是不一样。所以每次使用之前先要初始化，去设置平台相关的信息。以下以win32的平台实现去分析：首先进入win32程序实现的入口文件：
bool AppDelegate::applicationDidFinishLaunching() {
// initialize director
auto director = Director::getInstance();
auto glview = director->getOpenGLView();
if(!glview) {
glview = GLView::create("My Game"); //创建GL对象
director->setOpenGLView(glview);
}
// turn on display FPS
director->setDisplayStats(true);
// set FPS. the default value is 1.0/60 if you don't call this
director->setAnimationInterval(1.0 / 60);
// create a scene. it's an autorelease object
auto scene = HelloWorld::createScene();
// run
director->runWithScene(scene);
return true;
}GLView* GLView::create(const std::string& viewName)
{
auto ret = new GLView;
if(ret && ret->initWithRect(viewName, Rect(0, 0, 960, 640), 1)) {//3.2之后。win32的窗体应该实在这里改，Android和其它平台也有相似的文件文件
ret->autorelease();
return ret;
} return nullptr;
}
设置GLView的初始化信息，比較有意思：
bool GLView::initWithRect(const std::string& viewName, Rect rect, float frameZoomFactor)
{
setViewName(viewName);//窗体名字 _frameZoomFactor = frameZoomFactor;//基础深度值。即Z轴 glfwWindowHint(GLFW_RESIZABLE,GL_FALSE); //这句我也没看懂，求教
win32注冊窗体，这个就是真正的窗体。为什么之前说cocos2d的程序是单窗体单线程，这里是就明确了，我们仅仅使用单例Director，永远仅仅管理一个窗体
_mainWindow = glfwCreateWindow(rect.size.width * _frameZoomFactor,
rect.size.height * _frameZoomFactor,
_viewName.c_str(),
_monitor,
nullptr);
glfwMakeContextCurrent(_mainWindow);//设置为当前画布（Contex也有翻译为上下文、文本） glfwSetMouseButtonCallback(_mainWindow, GLFWEventHandler::onGLFWMouseCallBack);//鼠标的相关事件监听，在移动平台则应该是Touch began end 、focus（切换屏幕或应用会触发）
glfwSetCursorPosCallback(_mainWindow, GLFWEventHandler::onGLFWMouseMoveCallBack);//拖动回调注冊
glfwSetScrollCallback(_mainWindow, GLFWEventHandler::onGLFWMouseScrollCallback);//滚屏事件注冊，平时我们拖动TableView时就是由这个进行直接回调
glfwSetCharCallback(_mainWindow, GLFWEventHandler::onGLFWCharCallback);//字符输入事件回调
</pre><pre code_snippet_id="498510" snippet_file_name="blog_20141027_8_222555" name="code" class="cpp"><pre name="code" class="cpp">/*
The key functions deal with physical keys, with layout independent
* [key tokens](@ref keys) named after their values in the standard US keyboard
* layout. If you want to input text, use the
* [character callback](@ref glfwSetCharCallback) instead.
glfwSetWindowPosCallback(_mainWindow, GLFWEventHandler::onGLFWWindowPosCallback);
glfwSetFramebufferSizeCallback(_mainWindow, GLFWEventHandler::onGLFWframebuffersize);
glfwSetWindowSizeCallback(_mainWindow, GLFWEventHandler::onGLFWWindowSizeFunCallback); setFrameSize(rect.size.width, rect.size.height);
*/
/*以上是原Api声明，实际意思：全部的物理键盘按键操作都会由这个触发，可是虚拟键盘的实现我还不清楚，应该是通过前面的MouseButton来之后调用CharCallback实现*/
glfwSetKeyCallback(_mainWindow, GLFWEventHandler::onGLFWKeyCallback);
glfwSetWindowPosCallback(_mainWindow, GLFWEventHandler::onGLFWWindowPosCallback); //屏幕拖动事件回调。在wp8和相关平台实现才须要
glfwSetFramebufferSizeCallback(_mainWindow, GLFWEventHandler::onGLFWframebuffersize);//帧缓存大小设置？谁知道细节
glfwSetWindowSizeCallback(_mainWindow, GLFWEventHandler::onGLFWWindowSizeFunCallback); //窗体大小的设置眼下在移动设备上是没有这个相关接口，win32和mac才有
// check OpenGL version at first
const GLubyte* glVersion = glGetString(GL_VERSION); if ( utils::atof((const char*)glVersion) < 1.5 ) //opengl1.5以上兼容
{
char strComplain[256] = {0};
sprintf(strComplain,
"OpenGL 1.5 or higher is required (your version is %s). Please upgrade the driver of your video card.",
glVersion);
MessageBox(strComplain, "OpenGL version too old");
return false;
} initGlew(); // Enable point size by default.
glEnable(GL_VERTEX_PROGRAM_POINT_SIZE); return true;
}
跳转
// helper
bool GLView::initGlew()
{
#if (CC_TARGET_PLATFORM != CC_PLATFORM_MAC)
GLenum GlewInitResult = glewInit();//OpenGL库固定初始化函数。 if (GLEW_OK != GlewInitResult)
{
MessageBox((char *)glewGetErrorString(GlewInitResult), "OpenGL error");
return false;
} if (GLEW_ARB_vertex_shader && GLEW_ARB_fragment_shader)
{
log("Ready for GLSL");
}
else
{
log("Not totally ready :(");
} if (glewIsSupported("GL_VERSION_2_0"))
{
log("Ready for OpenGL 2.0");
}
else
{
log("OpenGL 2.0 not supported");
} #if (CC_TARGET_PLATFORM == CC_PLATFORM_WIN32)
if(glew_dynamic_binding() == false) //OpenGL是一个单独的状态机。须要使用window OpenGL的api去完毕硬件绑定。 用设计模式的思想能够当做OpenGL是个策略模式中的策略。而window OpenGL则是提供策略支持详细实现。<span style="font-family: Arial, Helvetica, sans-serif;">window OpenGL</span><span style="font-family: Arial, Helvetica, sans-serif;">同一时候的代理（window os才是真正去管理硬件的总代理） wgl的细节我也不熟。就此搁置</span>
{
MessageBox("No OpenGL framebuffer support. Please upgrade the driver of your video card.", "OpenGL error");
return false;
}
#endif #endif // (CC_TARGET_PLATFORM != CC_PLATFORM_MAC) return true;
}
#if (CC_TARGET_PLATFORM == CC_PLATFORM_WIN32)
static bool glew_dynamic_binding()
{
const char *gl_extensions = (const char*)glGetString(GL_EXTENSIONS); // If the current opengl driver doesn't have framebuffers methods, check if an extension exists
if (glGenFramebuffers == nullptr)
{
log("OpenGL: glGenFramebuffers is nullptr, try to detect an extension");
if (strstr(gl_extensions, "ARB_framebuffer_object"))
{
log("OpenGL: ARB_framebuffer_object is supported"); glIsRenderbuffer = (PFNGLISRENDERBUFFERPROC) wglGetProcAddress("glIsRenderbuffer");
glBindRenderbuffer = (PFNGLBINDRENDERBUFFERPROC) wglGetProcAddress("glBindRenderbuffer");
glDeleteRenderbuffers = (PFNGLDELETERENDERBUFFERSPROC) wglGetProcAddress("glDeleteRenderbuffers");
glGenRenderbuffers = (PFNGLGENRENDERBUFFERSPROC) wglGetProcAddress("glGenRenderbuffers");
glRenderbufferStorage = (PFNGLRENDERBUFFERSTORAGEPROC) wglGetProcAddress("glRenderbufferStorage");
glGetRenderbufferParameteriv = (PFNGLGETRENDERBUFFERPARAMETERIVPROC) wglGetProcAddress("glGetRenderbufferParameteriv");
glIsFramebuffer = (PFNGLISFRAMEBUFFERPROC) wglGetProcAddress("glIsFramebuffer");
glBindFramebuffer = (PFNGLBINDFRAMEBUFFERPROC) wglGetProcAddress("glBindFramebuffer");
glDeleteFramebuffers = (PFNGLDELETEFRAMEBUFFERSPROC) wglGetProcAddress("glDeleteFramebuffers");
glGenFramebuffers = (PFNGLGENFRAMEBUFFERSPROC) wglGetProcAddress("glGenFramebuffers");
glCheckFramebufferStatus = (PFNGLCHECKFRAMEBUFFERSTATUSPROC) wglGetProcAddress("glCheckFramebufferStatus");
glFramebufferTexture1D = (PFNGLFRAMEBUFFERTEXTURE1DPROC) wglGetProcAddress("glFramebufferTexture1D");
glFramebufferTexture2D = (PFNGLFRAMEBUFFERTEXTURE2DPROC) wglGetProcAddress("glFramebufferTexture2D");
glFramebufferTexture3D = (PFNGLFRAMEBUFFERTEXTURE3DPROC) wglGetProcAddress("glFramebufferTexture3D");
glFramebufferRenderbuffer = (PFNGLFRAMEBUFFERRENDERBUFFERPROC) wglGetProcAddress("glFramebufferRenderbuffer");
glGetFramebufferAttachmentParameteriv = (PFNGLGETFRAMEBUFFERATTACHMENTPARAMETERIVPROC) wglGetProcAddress("glGetFramebufferAttachmentParameteriv");
glGenerateMipmap = (PFNGLGENERATEMIPMAPPROC) wglGetProcAddress("glGenerateMipmap");
}
else
if (strstr(gl_extensions, "EXT_framebuffer_object"))
{
log("OpenGL: EXT_framebuffer_object is supported");
glIsRenderbuffer = (PFNGLISRENDERBUFFERPROC) wglGetProcAddress("glIsRenderbufferEXT");
glBindRenderbuffer = (PFNGLBINDRENDERBUFFERPROC) wglGetProcAddress("glBindRenderbufferEXT");
glDeleteRenderbuffers = (PFNGLDELETERENDERBUFFERSPROC) wglGetProcAddress("glDeleteRenderbuffersEXT");
glGenRenderbuffers = (PFNGLGENRENDERBUFFERSPROC) wglGetProcAddress("glGenRenderbuffersEXT");
glRenderbufferStorage = (PFNGLRENDERBUFFERSTORAGEPROC) wglGetProcAddress("glRenderbufferStorageEXT");
glGetRenderbufferParameteriv = (PFNGLGETRENDERBUFFERPARAMETERIVPROC) wglGetProcAddress("glGetRenderbufferParameterivEXT");
glIsFramebuffer = (PFNGLISFRAMEBUFFERPROC) wglGetProcAddress("glIsFramebufferEXT");
glBindFramebuffer = (PFNGLBINDFRAMEBUFFERPROC) wglGetProcAddress("glBindFramebufferEXT");
glDeleteFramebuffers = (PFNGLDELETEFRAMEBUFFERSPROC) wglGetProcAddress("glDeleteFramebuffersEXT");
glGenFramebuffers = (PFNGLGENFRAMEBUFFERSPROC) wglGetProcAddress("glGenFramebuffersEXT");
glCheckFramebufferStatus = (PFNGLCHECKFRAMEBUFFERSTATUSPROC) wglGetProcAddress("glCheckFramebufferStatusEXT");
glFramebufferTexture1D = (PFNGLFRAMEBUFFERTEXTURE1DPROC) wglGetProcAddress("glFramebufferTexture1DEXT");
glFramebufferTexture2D = (PFNGLFRAMEBUFFERTEXTURE2DPROC) wglGetProcAddress("glFramebufferTexture2DEXT");
glFramebufferTexture3D = (PFNGLFRAMEBUFFERTEXTURE3DPROC) wglGetProcAddress("glFramebufferTexture3DEXT");
glFramebufferRenderbuffer = (PFNGLFRAMEBUFFERRENDERBUFFERPROC) wglGetProcAddress("glFramebufferRenderbufferEXT");
glGetFramebufferAttachmentParameteriv = (PFNGLGETFRAMEBUFFERATTACHMENTPARAMETERIVPROC) wglGetProcAddress("glGetFramebufferAttachmentParameterivEXT");
glGenerateMipmap = (PFNGLGENERATEMIPMAPPROC) wglGetProcAddress("glGenerateMipmapEXT");
}
else
{
log("OpenGL: No framebuffers extension is supported");
log("OpenGL: Any call to Fbo will crash!");
return false;
}
}
return true;
}
#endif