ArahWeave has a special function for constructing multiple layer (double) weaves; you specify basic weave for each warp against each weft and the program automatically constructs the composite weave. This function is available as a special popup window on in weave editor, named Edit decomposed. If you position your windows properly, you can view fabric simulation, normal weave editor and decomposed editor, all at the same time. And you can also enable the display of horizontal and vertical cross section. Cross section is interactive - it shows you the cut at the current mouse position. Even more - you can draw with mouse and change position of threads, and weave will be modified accordingly.
In the picture below, you have a weave with 1 warp and 3 wefts, with 5-satin on top and 5-satin on back for attachment of second weft, and 10-satin for attachment of third weft. But as a true weaver, you know all this...
The mysterious double interchanging plain weave from density explanation is much more understandable if we view it in the Edit Decomposed window.
With the right tools, everything suddenly becomes easy and logical.
You can edit even more complicated composed weaves, for instance those with different densities of top and bottom fabrics.
Do not be scared away by the following picture - many experienced weavers would also find it difficult.
We have a special double fabric with uneven top and bottom density, plus an extra weft which is hidden
in the middle and just links the two fabrics together. The warp layout is simple: 112 (we can write it also as 2a1b)- this means that first two warp ends go in first block, and third warp ends goes into second block. In this way we have
two times higher density in warp. Weft is similar, just that we need to repeat the layout until the
end, so we can add the third block for extra hidden thread: 8(2a1b)1c. Yes, it is just copy of weft repeat pattern. We enter elongated twill for the top fabric, and regular 2/2 twill for back fabric. The middle weft thread (shown in red)
has just two points which link it to the top and to the bottom fabric. We also add a regulator (stop motion) on the
middle weft thread, so that it does not disturb the weft density of the fabric. Note that the fabric simulation
in the lower left angle does not show any threads from the back (grey) or middle (red), since they are completely
covered by the top fabric (black weft and dark blue warp).
We have no ambitions to teach you weaving here - if you do not understand it, than you probably do not need this. But if you do, you see that it that design of complex weaves with ArahWeave is very easy. (If you know what you are doing... ;-)