The framebuffer bound to GL_READ_FRAMEBUFFER is then used for all read operations like glReadPixels and the framebuffer bound to GL_DRAW_FRAMEBUFFER is used as the destination for rendering, clearing and other write operations. It is also possible to bind a framebuffer to a read or write target specifically by binding to GL_READ_FRAMEBUFFER or GL_DRAW_FRAMEBUFFER respectively. To bind the framebuffer we use glBindFramebuffer:īy binding to the GL_FRAMEBUFFER target all the next read and write framebuffer operations will affect the currently bound framebuffer. This pattern of object creation and usage is something we've seen dozens of times now so their usage functions are similar to all the other object's we've seen: first we create a framebuffer object, bind it as the active framebuffer, do some operations, and unbind the framebuffer. Just like any other object in OpenGL we can create a framebuffer object (abbreviated to FBO) by using a function called glGenFramebuffers: First we'll discuss how they actually work and then we'll use them by implementing those cool post-processing effects. The application of framebuffers may not immediately make sense, but rendering your scene to a different framebuffer allows us to use that result to create mirrors in a scene, or do cool post-processing effects for example. By creating our own framebuffer we can get an additional target to render to. The default framebuffer is created and configured when you create your window (GLFW does this for us). The rendering operations we've done so far were all done on top of the render buffers attached to the default framebuffer. OpenGL gives us the flexibility to define our own framebuffers and thus define our own color (and optionally a depth and stencil) buffer. The combination of these buffers is stored somewhere in GPU memory and is called a framebuffer. So far we've used several types of screen buffers: a color buffer for writing color values, a depth buffer to write and test depth information, and finally a stencil buffer that allows us to discard certain fragments based on some condition. Framebuffers Advanced-OpenGL/Framebuffers
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