+unsigned VertexFormat::stride() const
+{
+ unsigned s = 0;
+ for(const unsigned char *i=begin(); i!=end(); ++i)
+ s += get_component_size(*i);
+ return s;
+}
+
+int VertexFormat::offset(VertexComponent comp) const
+{
+ unsigned type = get_component_type(comp);
+ unsigned size = get_component_size(comp);
+ unsigned offs = 0;
+ for(const unsigned char *i=begin(); i!=end(); ++i)
+ {
+ if(get_component_type(*i)==type)
+ {
+ if(get_component_size(*i)>=size)
+ return offs;
+ else
+ return -1;
+ }
+ else
+ offs += get_component_size(*i);
+ }
+
+ return -1;
+}
+
+VertexComponent make_indexed_component(VertexComponent comp, unsigned index)
+{
+ if(comp>=TEXCOORD1 && comp<=TEXCOORD4)
+ {
+ if(index>=4)
+ throw out_of_range("make_indexed_component");
+ }
+ else if(comp>=ATTRIB1 && comp<=ATTRIB4)
+ {
+ if(index>=24)
+ throw out_of_range("make_indexed_component");
+ }
+ else
+ throw invalid_argument("make_indexed_component");
+ return static_cast<VertexComponent>(comp+index*4);
+}
+