结合使用带有Qt的OpenGL帧缓冲区对象（QOpenGLWidget），如何在绘制到帧缓冲区时禁用多重采样

Question

As the title suggests, I'm using Qt for OpenGL drawing, and with QOpenGLWidget I can turn on multisampling for the main screen buffer with QSurfaceFormat's setSamples() function. This works fine and looks pretty nice. However, I'm also drawing into a custom frame buffer (using glGenFramebuffers, glBindFramebuffer(), etc) in the background, where I don't want anti-aliasing (since it's drawing using color encoding for selection purposes), but it seems to be inheriting the multi-sampling from the main QOpenGLWidget somehow. Any ideas on how to disable that, to use multisampling in the main window but not in my own custom off-screen frame buffers?

Answer 1

Multisampled rendering is enabled or disabled by using the glEnable/Disable(GL_MULTISAMPLE) . This state is not part of the framebuffer's state; it's regular context state. As such, even when you switch framebuffers, that state will be unaffected.

Additionally, the multisample enable/disable switch doesn't mean anything if your attached images don't have multiple samples. If you're creating images for non-multisampled rendering, there's no reason to create them with multiple samples. So create single-sample images.

Answer 2

好吧，在我的OpenGL代码中找不到禁用或避免它的方法，但是如果我将默认格式设置为0个样本，而QOpenGLWidget的格式设置为2/4/8 /，则为framebuffer对象创建抗锯齿功能时将不会使用它。