_s Specifies the index used when the stencil buffer is cleared. The
initial value is 0.
DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
ffffggggllllCCCClllleeeeaaaarrrrSSSStttteeeennnncccciiiillll specifies the index used by ffffggggllllCCCClllleeeeaaaarrrr to clear the stencil
m
buffer. _s is masked with 2 -1, where m is the number of bits in the
stencil buffer.
EEEERRRRRRRROOOORRRRSSSS
GGGGLLLL____IIIINNNNVVVVAAAALLLLIIIIDDDD____OOOOPPPPEEEERRRRAAAATTTTIIIIOOOONNNN is generated if ffffggggllllCCCClllleeeeaaaarrrrSSSStttteeeennnncccciiiillll is executed between
the execution of ffffggggllllBBBBeeeeggggiiiinnnn and the corresponding execution of ffffggggllllEEEEnnnndddd.