Thanks guys! I really appreciate you taking the time to look at it and give me notes!
I agree on the deflating thing. I'm working on a better solution where I start the rot on the bite section, and then let it grow, rather than just letting it all collapse at once. So good call out! Interestingly enough if you look up how long it takes an apple to decay it's around 200 days. I was skeptical as well, but if you're curious here is a link to a reference I used. It's pretty crazy stuff. I assume it has to do with environment (how wet, how hot...etc) and how the bacteria is able to grow. Because I've seen apples at my place decay faster than 200 days! Haha https://www.youtube.com/watch?v=ajay1tq_roU
I think you're totally right about the lighting/shading! I'll try to find some reference photos for apples. I'm struggling to get a good breakup on the spread of the rott. I'm gonna take another crack at it, but I'm using a point propagator and I don't know how to slow it down other than using a lot of substeps and timewarping it - so it's kinda just moving across the surface. I could try randomly delete points inside the growth line, but I'm not sure if that'll help. I might try adding noise to the spread of points BEFORE I propagate them so that it goes over dead spots sometimes.
I like the juice idea, but I haven't found that in most of the videos I see on apples. It would seem apples don't really 'leak' juice. They sort of dry out as they go. That's not to say I couldn't add it under 'artistic' license. So you may be onto something.
Thanks again guys!