Creating a particle system using transform feedback
Transform feedback provides a way to capture the output of the vertex (or geometry) shader to a buffer for use in subsequent passes. Originally introduced into OpenGL with version 3.0, this feature is particularly well-suited for particle systems, because among other things, it enables us to do discrete simulations. We can update a particle's position within the vertex shader and render that updated position in a subsequent pass (or the same pass). Then the updated positions can be used in the same way as input to the next frame of animation.
In this example, we'll implement the same particle system from the previous recipe (Creating a particle fountain), this time making use of transform feedback. Instead of using an equation that describes the particle's motion for all time, we'll update the particle positions incrementally, solving the equations of motion based on the forces involved at the time each frame is rendered.
A common technique...
