cdb47b9dfc
Use multiple threads for building the MIS table, if the resolution is higher than 512. Also replace division by cdf_total, with a inverse multiplication by cdf_total_inv. This gives further speedup. On my Macbook (8 CPU threads) this improves the time to build the table: Resolution 4096: From 0.16s to 0.03s Resolution 8096: From 0.61s to 0.11s This especially helps to reduce the scene update time, when tweaking world shader while viewport rendering is running. Patch by Sergey and myself. Differential Revision: https://developer.blender.org/D1159