[WIP] Pin-Up with Transparency/Shrink-Wrapping (Patreon)

Hey all!

Sorry for the delay, but I'm nearly finished with this month's Pin-Up! The reason it's been taking so much longer than usual is because I've been trying a new shrink-wrap technique to better fit clothes to a growing character. It's a bit finicky with finding the best vertex weights, but the result is pretty convincing, and cuts out a ton of tedious sculpting. Not only that, I also only have to modify the character's base mesh and the shrinkwrapped clothes follows the contours almost perfectly! So far, I've only tested this with pin-ups, but I'm planning on trying the effect with animations as well. Ideally, this would save me a lot of time making manual corrective shape keys for clipping and expansion stages, but if I've learned anything yet, it's that the execution isn't going to be that simple. 

In addition to the shrinkwrap, I've been testing out painted/gradual transparency. This technique is pretty similar to how you can add makeup, decals, etc. to objects, but this time it uses the alpha channels in conjunction with a few mix+color ramps to tune in the gradual effect. I'm hoping that this'll help improve the expansion effect and emulate cloth fibers stretching thinner, and give the resulting renders a more realistic look. I think I can come up with an even better and more flexible effect using a set of empties connected to the armature, but for the time being hand-painting will do fine. 

Finally, I've been making some good progress on the breast physics! The main issue that I've been grappling with is how to maintain volume and keep specific features from deforming and/or not simulating when they end up growing (i.e nipples). I'd originally tried to jack up the stiffness/bending in the desired area, but the shape either collapsed or vibrated uncontrollably. The nipples have a lot of extra geometry in them (for shape keys), and unfortunately Blender's cloth sim applies mass to each vertex equally, meaning that high-density geometry is super heavy and tends to collapse inwards without extreme pressure/support. To combat this, I then switched over to a mesh deform method with a simplified mesh, but I kept running in to a strange issue where the deforming mesh would behave strangely when moved by the character armature. This sent me down another rabbit hole, but I eventually came up with a solution that more or less works. I've yet to make a example/test animation, but the effect is already a lot better than I had done before, and it seems to be a bit easier to customize. In case the mesh deform doesn't work however, I've been having great results with a standard surface deform, but unfortunately the nature of that modifier doesn't allow for character shape adjustments (i.e nipple resizing), and adjusting the surface mesh has been less than reliable. Maybe I can get around that with a bit more testing, but that's a task for another day. 

Either way, that's enough rambling for now. I'm looking to get the pin-up finished Thursday, and if I have time I'll plan to iron out a few more physics issues before making a short test animation. Despite the setbacks, it's nice to have more techniques in my toolbox, and I'm looking forward to getting the chance to use them in more work!