These are general parameters used in multiple Material Tools Programs. Many have to do with multi-thread management. Many of the material tools programs are built to run on large sets of textures and materials. The calculations run faster when they are being run in parallel on multiple processor cores.
Parameters
Auto Select # Threads:
Auto selects how many parallel threads are used for calculation based on the number of inputs and the total number of processor cores in the computer being used.
In Mask and Overlay, this option also limits the number of threads used based on an estimate of memory usage. It should be noted that this estimate is not an exact calculation, and manual adjustment may be necessary, especially if there are several other programs open on your computer. The estimate allows for 3GB of memory being used by your operating system and all other programs.
Number of Threads
This determines how many processor cores are used for calculations. The main thread running the program is thread number 0 and manages loading textures, starting threads, and writing output textures, materials, and save files. At least one other thread is needed for calculations. The maximum value you can use for the Number of Threads is the number of cores in your CPU – 1.
This number of threads does not include the main thread. The maximum number of threads that can be selected must leave a processing core free for the main thread.
Mask and Overlay is additionally limited to using nine calculation threads and the main thread. Mask and Overlay has memory concerns that the other Material Tools programs do not. Mask and Overlay has the potential to fill up the memory with textures first, causing a massive slow down as the program utilizes virtual memory. In more extreme cases, the virtual memory will fill up, and Unity3D will crash.
The main thread does a considerable portion of the processing load for all Material Tools Programs. Many operations can only be done on the main thread, such as reading and writing, to the hard drive. The main thread is an unavoidable bottleneck for calculation. Since the main thread also has to handle whatever else is running on your computer, processing speed is affected by anything else that is open on the computer.
Output Subscript
A subscript appended onto the file name of your input texture’s name used as the name of your output texture and output material.