fix viewer. scheme was not set appropriately.
fix viewer. scheme was not set appropriately.

takahito-tejima/OpenSubdiv,takahito-tejima/OpenSubdiv-exp,anshuarya/OpenSubdiv,c64kernal/OpenSubdiv,nyotis/OpenSubdiv,poljere/OpenSubdiv,xldeveloper/OpenSubdiv,xldeveloper/OpenSubdiv,jcowles/OpenSubdiv,nyotis/OpenSubdiv,nyotis/OpenSubdiv,jcowles/OpenSubdiv,shengfuintel/OpenSubdiv,jcowles/OpenSubdiv,c64kernal/OpenSubdiv,lookup1980/OpenSubdiv,takahito-tejima/OpenSubdiv,takahito-tejima/OpenSubdiv,takahito-tejima/OpenSubdiv-exp,anshuarya/OpenSubdiv,xldeveloper/OpenSubdiv,anshuarya/OpenSubdiv,shengfuintel/OpenSubdiv,shengfuintel/OpenSubdiv,lookup1980/OpenSubdiv,c64kernal/OpenSubdiv,takahito-tejima/OpenSubdiv-exp,takahito-tejima/OpenSubdiv-exp,poljere/OpenSubdiv,lookup1980/OpenSubdiv,poljere/OpenSubdiv