Framebuffer objects (FBOs) are crucial in modern 3D graphics pipelines as they enable efficient off-screen rendering and facilitate advanced techniques like post-processing and shadow mapping. FBOs store intermediate results, such as color, depth, and stencil buffers, allowing multiple render targets and avoiding the need to copy data between textures.

In post-processing, FBOs allow applying effects like bloom or motion blur by rendering a scene to an off-screen texture, then using that texture for further processing. For example:

1. Render the scene to an FBO with a color attachment.
2. Apply a Gaussian blur on the horizontal axis to the color attachment.
3. Use another FBO to apply Gaussian blur on the vertical axis.
4. Combine the blurred result with the original scene using additive blending. For shadow mapping, FBOs help create depth maps representing distances from light sources to surfaces. The process involves:

1. Create an FBO with a depth attachment.
2. Render the scene from the light’s perspective, storing depth values in the FBO.
3. Bind the depth map as a texture when rendering the scene from the camera’s view.
4. Compare current fragment’s depth value to the stored depth value to determine if it is in shadow.