From: Jeffrey Holle (jeff.holle_at_[hidden])
Date: 2004-12-15 18:12:28
Maybe you should be looking at std::advance?
Eli Pulsifer wrote:
> Hello,
>
>
>
> I have a situation which is probably quite common and already addressed
> by boost.
>
> So rather than write it my self, maybe someone can point me to the answer.
>
>
>
> I’ve got a geometry class that needs to expose iterators for the
> underling vertex components.
>
> Example:
>
>
>
> Class Vertex
>
> {
>
> positions_iterator PositionsBegin();
>
> positions_iterator PositionsEnd();
>
> normals_iterator NormalsBegin();
>
> normals _iterator NormalsEnd();
>
> …
>
> }
>
>
>
> The first problem is depending on the format of the underling vertices,
> the stride between the data elements will change.
>
> Is there some easy way to implement this?
>
>
>
> I think writing my own using the boost::iterator_adapter is probably the
> way to go.
>
>
>
> Second problem is more involved.
>
>
>
> The texture data not only has a stride but a variable number of elements.
>
> Some vertices have 2 texture coordinates, some 3, some even more.
>
>
>
> Id love to define this iterator like this:
>
> stride_iterator< pair<float_iterator, float_iterator> > tex_coord_iterator;
>
>
>
> then create the iterator:
>
>
>
> stride_tupel_iterator< pair<float_iterator, float_iterator> >(
> pFirstTexCoord, texCoordStride, texCoordCount );
>
>
>
> then use it:
>
>
>
> stride_tupel_iterator< pair<float_iterator, float_iterator> > it;
>
>
>
> for( it = vertex.PositionBegin() ; it != vertex.PositionEnd() ; ++it)
>
> {
>
> pair<float_iterator, float_iterator> coords;
>
> float_iterator iCoord;
>
>
>
> for(iCoord = coords.first ; iCoord != coords.last ; ++iCoord)
>
> {
>
> }
>
> }
>
>
>
> This will probably also require me to create my own highly special
> iterator class or is there a better way.
>
>
>
>
>
>
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>
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