opengl - Can we render to screen while also extracting the points? -

i have 2 streams, 1 of point clouds , 1 of fullscreen textures. want colour points using texture , render them, want store resulting coloured pointclouds later analyzes , usage. can somehow without sending data unit, colour points on gpu, extract host , send unit again in order render it? mean can done using gpu computing , store data allocated memory on unit, later extract, sending data unit processing , later sending same data unit rendering seems redundant. have never done other rendering screen before not sure.

if possible, need cuda or can without? how done?

edit: example of hope achieve. arrows indicate moving data , | symbolizes wall between 2 sides.

unit            | host -------------------------------------------------------------------------------------------                 ← pointcloud , texture         //input data colour points   | wait                           //colour points using gpu coloured points →                                //extract coloured points render points   | whatever points.   // render screen , use coloured points on cpu 

an example of hope avoid. arrows indicate moving data , | symbolizes wall between 2 sides.

unit            | host -------------------------------------------------------------------------------------------                 ← pointcloud , texture         //input data colour points   | wait                           //colour points using gpu coloured points →                                //extract coloured points                 ← coloured points                //send exact same data again render points   | whatever points.   // render screen , use coloured points on cpu