Sergey Sharybin
67cec97387
The idea is to give a control over direction of twist, and maybe amount of twist as well. More concrete example: make braids on left and right side of character head to be twisting opposite directions. Now, tricky part: we need some negative values to flip direction, but weights can not be negative. So we use same trick as displacement map and tangent normal maps, where 0.5 is neutral, values below 0.5 are considered negative and values above 0.5 are considered positive.