Hey Luis, > > I have another question, when you say that the "pdata-index-map! supplies > the current pdata index number to the procedure", do you refer that I am > giving a name to the current pdata? > > Well, no. What pdata-index-map! does is iterate over the pdata like pdata-map! does (that means; it goes over all vertices in turn) and in addition to the reference to the vector in question you also get the "index" of that vector, being a integer between 0 and (pdata-size).
This is useful because when you know you are dealing with a list of triangles, for example, you will know that indexes 0, 1 and 2 refer to the corners of one polygon and 3, 4 and 5 refer to another but there is no polygon using indexes 1, 2 and 3. In the case of a quad-list you'd likely treat the indexes differently. Within the function you apply to to these vertices you may use any name you like as a local variable. The example you give doesn't actually use the "index" part of "pdata-inex-map!", but with these notes the example you get when you type (help pdata-index-map!) might make more sense. Hope that helps, Kas.
