Imagine I render to an FBO some arbitrary geometry. Geometry can be rendered via single or multiple draw calls. For the sake of the question, assume I know nothing about geometry or transformation matrices.
I need to efficiently read back the minimal screen-space bounding box of all drawn geometry after the rendering to FBO is finished.
I imagine this can be done with via use of atomics on an image (imageLoad/imageStore) or SSBO, sadly these are not available to me. Is there any other mechanism I can try?