@Duta thanks for replying. I looked into your code. You were using the same model with this one.For the JellyPentagon class, you build 10 springs in a soft body. As I said, it would need N(N - 1) / 2 springs for a shape has N sides. When N comes lager, the scenario comes slow. I was looking for another model which is better. It's called "Pressure Soft Body" which suppose there were some ideal "gas" in the soft body to support it.

Hi, BuilderBoy. This scenarios is awesome. I'm looking into soft body these days. May I ask, how did it expands to other shape. I looked into your code and find out it was based on the "mass point - spring net" model. If it is a shape with N sides, the number of springs would come to N(N - 1) / 2 (if you put a spring between every two mass points), when N is lager than about 30, things became slow. I search on the internet and find there is an other model called PSB(pressure soft body), it's similar with this one, but the amount of calculation is much less(I think it's about 2N). I tried PSB in greenfoot, but the the effect is not ideal. I thought I'd better share the infomation with you(or anybody who was interested in soft body simulation), hope we can have a better model one day.

@bourne Yes, I think it's awesome! I'm interested in how you did syntax check, could you tell me they are in witch class? There are too many of them

@JetLennit It something like this one: http://www.greenfoot.org/scenarios/5681

Couldn't see your code, but why not try to give the tail of the ball(those black bricks followed the ball) a transparency fade out? I thought that could be better.