+int VertexFormat::offset(VertexComponent comp, unsigned index) const
+{
+ if((comp<TEXCOORD1 && index>0) || (comp<ATTRIB1 && index>=8) || index>=53)
+ throw out_of_range("VertexFormat::offset");
+
+ unsigned type = (comp>>2)+index;
+ unsigned size = comp&3;
+ unsigned offs = 0;
+ for(const unsigned char *i=begin(); i!=end(); ++i)
+ {
+ if(static_cast<unsigned>(*i>>2)==type)
+ {
+ if((*i&3)>=size)
+ return offs;
+ else
+ return -1;
+ }
+ else
+ offs += (*i&3)+1;
+ }
+
+ return -1;
+}
+