API: OpenGL - Framebuffer / Renderbuffer

[bryphe]

Being able to create your own framebuffer and renderbuffer in OpenGL is very powerful - it allows you to render a scene to a texture, and then reuse this texture in your rendering pipeline.

This is used in several areas:

• Shadow mapping - a common implementation is to render a scene from a light's perspective, and then use that 'shadow map' to determine if a fragment is lit or not.
• Post-processing - running the rendered scene through another pixel shader, for example, to implement screen-space ambient occlusion
• Optimized Rendering - for revery, if a component is not updated frequently, we can cache the rendering result in a texture instead of rendering all of the components. Needed for Performance - Advanced: ContainerNode that uses a render texture revery#54