我正在学习OpenGL,所以我正在尝试绘制2D图像。 我首先将所有内容都放在我的C ++程序的主要功能中。它运行良好(绘制了2个三角形)。
我决定通过制作单独的课程来使程序更清晰,...... 但现在它已不再适用了。当我想制作OpenGL上下文时,它失败了。当我显示错误时:
Failed creating OpenGL context at version requested
在我正在阅读的教程中,他们说这个错误很可能是因为您的显卡不支持OpenGL的版本,但如果是这样的话,它就不应该工作当我把所有代码都放在主程序中时。
这是出错的部分(上下文创建):
bool OpenGL_Scene::initializeWindow() {
// Initialize the SDL
if(SDL_Init(SDL_INIT_VIDEO) < 0)
{
cout << "Error while initializing the SDL : " << SDL_GetError() << endl;
SDL_Quit();
return false;
}
// Configure OpenGL
// Use version 3.1
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3); // OpenGL 3.x
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 1); // OpenGL x.1 --> OpenGL 3.1
// Double buffering
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1); // Use double buffering (0 to not use it)
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24); // Buffer has a depth of 24 bits
// Make the window
this->window = SDL_CreateWindow(this->windowTitle.c_str(), SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, this->windowWidth, this->windowHeight, SDL_WINDOW_SHOWN | SDL_WINDOW_OPENGL); // SDL_WINDOW_OPENGL necessary to specify that the window will have an OpenGL context attached to it.
if(this->window == 0) // Initialization failed
{
cout << "Error while creating the window : " << SDL_GetError() << endl;
SDL_Quit();
return false;
}
// Make the OpenGL context given the SDL window
this->OpenGL_Context = SDL_GL_CreateContext(this->window);
// Make sure the creation of the context succeeded. If not the problem is probably that the version of OpenGL isn't supported by the graphics card.
if(this->OpenGL_Context == 0)
{
cout << "Could not create the OpenGL context : " << SDL_GetError() << endl;
SDL_DestroyWindow(window);
SDL_Quit();
return false;
}
return true;
};
在最后几行中显示错误,以便程序产生:
Could not create the OpenGL context : Failed creating OpenGL context at version requested
我搜索了很多寻找解决方案并发现了这个: SO topic
所以在上面的代码中我尝试了:
// Configure OpenGL
// Use version 3.1
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3); // OpenGL 3.x
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 1); // OpenGL x.1 --> OpenGL 3.1
// Double buffering
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE); // ADDING THIS AVOIDS THAT THE CONTEXT COULD NOT BE CREATED BUT THEN WHEN WE DRAW SOMETHING WE DON'T SEE ANYTHING
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1); // Use double buffering (0 to not use it)
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24); // Buffer has a depth of 24 bits
现在当我使用此附加行运行程序时,创建上下文(没有错误,因此OpenGL_Context != 0
)但没有绘制任何内容< / strong>即可。我省略了我正在绘制的代码部分,因为它以前工作过,我没有改变任何东西。
有人知道可能出现什么问题吗?
PS:我正在使用Macbook Pro(OS X Yosemite(10.10.4))而我的显卡是NVIDIA GeForce GT 650M 1024 MB
编辑:我尝试调试绘制三角形的代码,但我真的没有看到错误(主要是因为我对OpenGL来说真的很新)。在下面你可以找到绘图代码。请注意,我不再对GLEW进行初始化,因为它不是必要的(根据评论)。
void OpenGL_Scene::mainLoop() {
bool end = false;
// Make vertices (punten) in a table
// !!! WARNING : Use 1 table for ALL vertices !!! Don't use a separate table for each of the forms, this would slow down the program because you have to send each of the tables to OpenGL !!!
float vertices[] = {-0.5, -0.5, 0.0, 0.5, 0.5, -0.5, // 3 Points for first triangle --> (-0.5, -0.5) , (0.0, 0.5) and (0.5, -0.5) (All in (x, y) --> 2D)
-0.8, -0.8, -0.3, -0.8, -0.8, -0.3}; // 3 Points for second triangle
// Before we start drawing, clear the screen
glClear(GL_COLOR_BUFFER_BIT);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, vertices);
glEnableVertexAttribArray(0); // Activate the table we passed to OpenGL using the identifier (index) passed to OpenGL (in this case 0)
// Now that OpenGL knows which vertices it has to display we are going to specify what it has to do with these vertices
glDrawArrays(GL_TRIANGLES, 0, 6); // Draw both triangles
glDisableVertexAttribArray(0); // Because it isn't necessary anymore
SDL_GL_SwapWindow(this->window); // Refresh the screen
while(!end) {
// Listen to events and play with them
SDL_WaitEvent(&this->events); // Will wait for an event and assign it to "events" variable
if(this->events.window.event == SDL_WINDOWEVENT_HIDDEN)
cout << "The user has hidden the window !" << endl;
else if(this->events.window.event == SDL_WINDOWEVENT_CLOSE) {
cout << "The user closed the window !" << endl;
glClear(GL_COLOR_BUFFER_BIT); // Clear the screen
SDL_GL_SwapWindow(this->window); // Refresh the window
end = true;
}
}
// Quitting the SDL and OpenGL properly is done by the destructor
}
所以现在当我执行项目时,首先我创建窗口(这是成功的)然后我调用mainLoop
过程(从上面)。
我使用调试器逐步绘制了绘图代码,调用了所有过程(glClear,...),但窗口中没有任何内容(它保持黑色)。
答案 0 :(得分:3)
我发现了错误。初始化SDL后我正在初始化OpenGL,这就是为什么在不强迫进入&#34;核心配置文件的情况下无法创建上下文的原因。
&#34; initializeWindow&#34;中的正确顺序是:
// Configure OpenGL
// Use version 3.1
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3); // OpenGL 3.x
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 1); // OpenGL x.1 --> OpenGL 3.1
// Double buffering
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1); // Use double buffering (0 to not use it)
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24); // Buffer has a depth of 24 bits
// Initialize the SDL
if(SDL_Init(SDL_INIT_VIDEO) < 0)
{
cout << "Error while initializing the SDL : " << SDL_GetError() << endl;
SDL_Quit();
return false;
}
这样做可以成功创建上下文。