1. It seems that only the bra template as a 150 frames available on the back layer. Is there a way to make this for the top template?
If your mod is classified as a BRA then the game will automatically attempt to set the back clothing layer (
g.her.torso.braStrap) to the appropriate frame #, whenever a change in breast size occurs.
I don't know why the template would have excluded a full timeline. Perhaps it's because the BRA modtype isn't properly supported in the vanilla game. I assume that you're using the SDT Loader (and that you intend to publish a Loader mod) so the question is moot. You can just
add those missing frames to your back template. You could even copy the entire layer from another Symbol, if you want to sync up the major keyframes closely. Then go ahead and draw whatever you want :)
If you're planning to publish a different type of mod (such as a TOP or OVERTOP) then we can easily add a bit of scripting to your mod. Feel free to extend the timeline out to 151 frames; we can send you the necessary script details to ensure that your back layer element gets updated/resized as needed. It's basically just a single call to
g.characterControl.addBreastSizeChangeListener(...), or we can do some lProxy post stuff if you want to be extra thorough.
Alternatively: if you're dealing with elastic material (such as straps) then you could attempt a physics-based approach. Instead of drawing 150 frames (with various shape adjustments and tweens), you could draw
one element (e.g. a strap) and then ask the game's physics system to stretch it between a designated set of endpoints.
Huit's
bikini mods are the best example of the latter approach. The
clamshell bra is a much simpler mod, but it might be easier to observe the elastic behavior because of its simplicity. It's important to note that the physics-based approach is unsuitable for
rigid elements. If you're planning to create a slider-adjustable breastplate then your original idea (keyframe/timeline animation) would be best.
It seems there is a layer that follows at the same time the right breast movement AND the back movement
I believe that you're describing the torso band of the bra.
The torso band consists of two
overlapping pieces, one on the
back layer and one on the
chest layer. They each have an animation timeline, and each sprite gets resized automatically to accommodate larger breasts (i.e. the band enlarges and slides farther down the torso). Because
@Konashion did his work carefully, the band appears to stretch
uniformly. It isn't immediately obvious that it consists of two separate sprites on different layers, which are being animated separately.
The vanilla SDT bra "cheats" a little bit - it uses a supplementary method (
BraStrap::Update) to slightly stretch and rotate the back+chest sprites so that the torso band of the bra remains "anchored" to the inframammary area. The vanilla SDT bikini uses a similar cheat to keep its shoulder strap connected to the top of the right cup. You might understand this "cheating" effect more easily if we
disable the correction behavior.
Here's a mod which will do that. Load the strapHack mod, then adjust the breast size OR make the girl breathe deeply OR move her around to induce breast jiggle -- you'll see that the linkage of the straps becomes much less accurate.
By comparison, WeeWillie's mod does
not suffer any ill effects from the strapHack mod -- because it was never
relying on SDT's bra-strap code. The Lacy Bra was drawn entirely on the
back and
chest layers, without using the
strap layers at all. If you'd like to follow WeeWille's approach then you're welcome to do so. If you'd like to include physics-based elastic links in your mod, then let me know and we can discuss the technical details.
It also seems this bottom part is a single one that goes to the back and everything remains very coherent.
As mentioned above: it's actually
two pieces, but they appear as one because of careful work by the artist.
This work is potentially
difficult because it's very tough to preview the animation. I don't know of any easy way to see (within the Flash workspace)
both the back and chest components simultaneously, in their proper spatial context, at a particular frame (e.g. #30). Therefore if you notice a problem (e.g. the torso band becomes jagged or kinked at a particular breast size) then you might need to perform a lot of trial-and-error adjustments in order to fix it ... instead of making a single precisely-targeted correction.
I believe that
@WeeWillie avoided this problem by copying some of the strap
shape data from
SDT.swf. I've never dealt with this problem because I don't actually draw anything; I merely adjust physics parameters until things look OK.
@Huitznahua may have dealt with this particular issue during his modding career - and he speaks French, so it would be a good idea to talk to him if you run into difficulty.
stuntcock
and @sby as I think they are very likely to have answers about this 
