Drawing style definition

Drawing styles definition and explanation

STD 0, standard - new color overrides everything

ADD 1, addition - colors are added (and clipped) by components

SUB 2, substitution - colors are substituted (and clipped) by components

MSKA 3, MASKING by color A

MSKB 4, MASKING by color B

MSKADD 5, MASKING by color A plus addition

BLD 6, blending colors by blend value