I figured it out, sorry for asking so fast before I even try it myself.

Basically, I convert to and from raw, and just copy the bits and pieces in
the right place.  Here's part of my code, where "image" is the final one,
and "char_image" is one of the smaller (I loop through all of them).

        Raw.sets (GlPix.to_raw image) ~pos:(3*(i*image_w + j + c*char_w))
             (Raw.gets (GlPix.to_raw char_image) ~pos:(3*(i * char_w + j))
~len:3)

Best,

Orlin

On 10/22/07, Orlin Grigorov <ogrigorov@gmail.com> wrote:
>
> Hi.  It's me again and my peculiar needs ;)
>
> At hand is the following problem.  Let's assume that we have the
> following:
>
> let image1 = GlPix.create `ubyte ~format:`rgb ~width:100 ~height:100 in
> .
> (* some code *)
> .
> let image2 = GlPix.create `ubyte ~format:`rgb ~width:100 ~height:100 in
> .
> (* some code *)
> .
> let image3 = GlPix.create `ubyte ~format:`rgb ~width:200 ~height:100 in
> (* ?????????? *)
>
> The question marks are to be filled with code, which will join image1 and
> image2 together (will glue them one next to the other), and the result will
> be stored in image3 (notice how the width is the sum of the other two
> widths).
>
> Please help!
>