1.8.4 polygon penetration

[Kilinich]

Polygon penetration problem still not fixed in 1.8.4
Scene created in Phun 5.28 - no penetration, no shakes.

[scene]49230[/scene]

[emilk]

Huh - thats a bug with polygon collision detection - good find! I'll look into it.

You can get the phun behavior by reverting to old collision detect via "Sim.useSkipLists = false;"

[emilk]

Ah, no, false alarm. It's not really a bug, more like a side effect. If you turn on collision visualisation via "App.drawCollisions = true;" you'll see that the old collision detection code generated farm more contacts, making the polygon more stable. That, unfortunately, also makes the simulation far slower. The old code (phun) also had this problem - try turning the polygon into a box and you'll see.

This general problem of light objects being crushed by heavy ones is an effect of the approximate solver used by Algodoo. You can make it more precise (at the cost of performance) via "Sim.solveIter" - for instance, setting it to 300 instead of the default 30 makes this scene much more stable.

[Kilinich]

So result is: On a high force contacts increase density. Other ways will work only on my algodoo.
Maybe just increase Sim.solveIter default value?

[Kilinich]

Ah, no, false alarm. It's not really a bug, more like a side effect. If you turn on collision visualisation via "App.drawCollisions = true;" you'll see that the old collision detection code generated farm more contacts, making the polygon more stable. That, unfortunately, also makes the simulation far slower.

btw:
Santa's portals scene (where I notice that polygon penetration bug... no... side effect)
1.6.0 - 28 FPS (old no-penetration behavior)
1.8.4 - 18 FPS

I understand Algodoo make a huge progress with interface, but what about performance

[mori-d]

See the below my old scene.(TJ-Dog)
http://www.algodoo.com/algobox/details.php?id=17485

This scene was made in Phun 4.22 at first, then re-uploaded as .phz file later.
It works fine in Phun 4.22 and 5.28.
But in Algodoo 1.8.5, the dog's foot pierces a thin polygon (slope of a hill) and stuck.
If Sim.solveIter = 300, the dog couldn't walk...
If Sim.solveIter = 100, the dog can walk but he jerks and stuck again...

I think this is Algodoo's bug, not a side effect...

[Kilinich]

Yea, this sucks. I've notice that in few scenes... what can I say.. don't use polygons...