[Gimp-user] Animations: Open as Layers to Double Animation but Maintain Replace.

[Seano <forums gimpusers com>]

Hello forum, this week I am attempting to build an animated logo for my website,
which will be a combination of two animated .GIFs when it is completed, (I am
working with .XCF format for all the editing).

As a quick explanation, my website name is comprised of two words, both
beginning with the letter 'O', and so I want to make one 'O' spin in a
left-to-right direction to represent planet Earth as observed from the common
Northern Hemisphere perspective, and the other 'o' half the size, to orbit
around the Big 'O', also in a left-to-right direction, to represent the Moon.

Because the Big 'O' will make a complete revolution of 24 layers in 2.0689
seconds, there will need to be 696 layers for the little 'o' to complete one
revolution in one minute.  This equates to 24 hours in a day and 29 days in a
lunar month (29x24=696).  It will be a huge image file at 1024x512 as .XCF, but
I will cut it down to 128x64 for the interlaced .GIF logo on the website.

I am using the 'Spinning-Globe' Script-Fu plugin to create my revolving letter
'O' from a flat base image, and then building both my spinning Big 'O' and
little 'o' after rotating the angles of 'spin' for each to their authentic
angles, and I have come across two problems which I have tried all day to find a
solution for, searching and reading for the last ten hours with no luck, which
is surprising.  Hence, as it is now 5pm in Perth, Australia, I have joined the
forum to ask for some help.

Here are my two problems:

1. I need to increase my Big 'O' animation from 24 layers to 696, to cause it to
rotate 29 revolutions within the centre of the whole animation, however although
the layers 'replace' properly when played back over 24 layers, when I use the
Files -> Open as Layers to append my 24 layered .XCF animation with a copy of
itself, and then playback, it replaces the first half of the two revolutions
with the transparent background, as expected, but then the second revolution
from the Open as Layers addition does not 'replace' the last layer image with
the new layer with different transparency.

How can I Open as Layers (or something else to append an .XCF file with more
layers), and maintain the 'replace' attribute so that the previous layer is
erased by the new layer, including transparent pixels?

2. As the Spinning-Globe plugin does not allow more than 360 layers, so I have
used 348 to create the orbit of the little 'o'. I need to double each layer in a
large number, so that layers 1,2,3,... and 1,2,3,... become layers
1,1,2,2,3,3,... and hope that there is some singular method to somehow Open as
Layers a copy of my 348 layer image and make each layer fall into place behind
its twin from the first.

How can I Open as Layers a copy of my image and append the added image's layers
to the current image's with a layer-by-layer sequence, rather than adding all
the layers of the new image to the end of the current image?

The first question is the most important, and probably the easiest one to
answer, I suspect, although it has certainly not for me all day today.  The
second question is one I could probably get around, but it will mean editing 696
frames by hand, and that will take a long long time, so I would be eternally
grateful if anyone might know some answer off the top of their head from past
experience, of which I have plenty of with GIMP for resizing .JPGs and very
little with creating large complex animations.

Thank you for reading this long request for help.  I will check back over the
next few days to see if anyone might have any answers to either problem.

-- 
Seano (via www.gimpusers.com/forums)