OpenGL Programming Guide: The Official Guide to Learning OpenGL, Version 4.3, Eighth Edition

Discarding Buffer Data

Advanced

When you are done with the data in a buffer, it can be advantageous to tell OpenGL that you don’t plan to use it any more. For example, consider the case where you write data into a buffer using transform feedback, and then draw using that data. If that drawing command is the last one that is going to access the data, then you can tell OpenGL that it is free to discard the data and use the memory for something else. This allows an OpenGL implementation to make optimizations such as tightly packing memory allocations or avoiding expensive copies in systems with more than one GPU.

To discard some or all of the data in a buffer object, you can call glInvalidateBufferData() or glInvalidateBufferSubData(), respectively. ...