In order to save some texture memory in a multi-step process, I am thinking of binding an FBO in order to update a small part of it with the scissor test enabled.
As I am not performing a glClear() in that case, what is the expected penalty for loading the data into on-chip memory ? Will the GPU restrict the data fetch to only those tiles intersecting the scissor box (it is very small compared to the overall texture, less than 5%) ?
Hi Martin,
Yes, this should work fine. The GPU will skip the region outside of the scissor for little performance hit (might be some rounding up to the tile size). You can verify the impact using the Streamline profiler - free download in Arm Mobile Studio.
HTH, Pete