我有ubuntu机器,以及用OS X编写的命令行应用程序,它使用FBO在屏幕外渲染。这是代码的一部分。
this->systemProvider->setupContext(); //be careful with this one. to add thingies to identify if a context is set up or not
this->systemProvider->useContext();
glewExperimental = GL_TRUE;
glewInit();
GLuint framebuffer, renderbuffer, depthRenderBuffer;
GLuint imageWidth = _viewPortWidth,
imageHeight = _viewPortHeight;
//Set up a FBO with one renderbuffer attachment
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glGenRenderbuffers(1, &renderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, renderbuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_RGB, imageWidth, imageHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, renderbuffer);
//Now bind a depth buffer to the FBO
glGenRenderbuffers(1, &depthRenderBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, depthRenderBuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, _viewPortWidth, _viewPortHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderBuffer);
“系统提供程序”是围绕OS X的NSOpenGLContext的C ++包装器,它仅用于创建渲染上下文并使其成为当前,而不将其与窗口相关联。所有渲染都发生在FBO中。
我正在尝试使用与GLX相同的Linux(Ubuntu)方法,但我很难做到这一点,因为我发现GLX需要一个像素缓冲区。
我正在尝试遵循本教程:
http://renderingpipeline.com/2012/05/windowless-opengl/
最后它使用一个像素缓冲区来使上下文变为当前,我听说它已弃用了,我们应该放弃它而选择Frame Buffer Objects,这是对的(我可能错了)。
有没有人有更好的方法或想法?
答案 0 :(得分:4)
我不知道这是否是最佳解决方案,但它肯定对我有用。
将函数绑定到我们可以使用的局部变量
typedef GLXContext (*glXCreateContextAttribsARBProc)(Display*, GLXFBConfig, GLXContext, Bool, const int*);
typedef Bool (*glXMakeContextCurrentARBProc)(Display*, GLXDrawable, GLXDrawable, GLXContext);
static glXCreateContextAttribsARBProc glXCreateContextAttribsARB = NULL;
static glXMakeContextCurrentARBProc glXMakeContextCurrentARB = NULL;
我们的对象作为类属性:
Display *display;
GLXPbuffer pbuffer;
GLXContext openGLContext;
设置上下文:
glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc) glXGetProcAddressARB( (const GLubyte *) "glXCreateContextAttribsARB" );
glXMakeContextCurrentARB = (glXMakeContextCurrentARBProc) glXGetProcAddressARB( (const GLubyte *) "glXMakeContextCurrent");
display = XOpenDisplay(NULL);
if (display == NULL){
std::cout << "error getting the X display";
}
static int visualAttribs[] = {None};
int numberOfFrameBufferConfigurations;
GLXFBConfig *fbConfigs = glXChooseFBConfig(display, DefaultScreen(display), visualAttribs, &numberOfFrameBufferConfigurations);
int context_attribs[] = {
GLX_CONTEXT_MAJOR_VERSION_ARB ,3,
GLX_CONTEXT_MINOR_VERSION_ARB, 2,
GLX_CONTEXT_FLAGS_ARB, GLX_CONTEXT_DEBUG_BIT_ARB,
GLX_CONTEXT_PROFILE_MASK_ARB, GLX_CONTEXT_CORE_PROFILE_BIT_ARB,
None
};
std::cout << "initialising context...";
this->openGLContext = glXCreateContextAttribsARB(display, fbConfigs[0], 0, True, context_attribs);
int pBufferAttribs[] = {
GLX_PBUFFER_WIDTH, (int)this->initialWidth,
GLX_PBUFFER_HEIGHT, (int)this->initialHeight,
None
};
this->pbuffer = glXCreatePbuffer(display, fbConfigs[0], pBufferAttribs);
XFree(fbConfigs);
XSync(display, False);
使用上下文:
if(!glXMakeContextCurrent(display, pbuffer, pbuffer, openGLContext)){
std::cout << "error with content creation\n";
}else{
std::cout << "made a context the current context\n";
}
之后,人们可以正常使用FBO,就像在任何其他场合一样。直到今天,我的问题实际上没有答案(如果有更好的选择),所以我只是提供一个对我有用的解决方案。在我看来,GLX不像OpenGL那样使用像素缓冲区的概念,因此我的困惑。渲染屏幕外的首选方法是FBO,但是要在Linux上创建OpenGL上下文,必须创建像素缓冲区(GLX类型)。之后,使用我在问题中提供的代码的FBO将按预期工作,就像在OS X上一样。