clear accum buffer after warmup frames for benchmarking
clear accum buffer after warmup frames for benchmarking

MengjiaoH/ospray,ospray/OSPRay,MengjiaoH/ospray,ospray/OSPRay,MengjiaoH/ospray,wilsonCernWq/ospray,wilsonCernWq/ospray,ospray/OSPRay,MengjiaoH/ospray,MengjiaoH/ospray,wilsonCernWq/ospray,ospray/OSPRay