miklosme / box2d-html5 Goto Github PK

> Setup:
Create a complex, static chain shape (a wonky circle with 100 edges). Make a 
small circle shape (r = 0.25) dynamic body, set IsBullet true and shoot it at 
the chain shape. I'm applying force towards the centroid of the chain shape 
(using it as a planet) and have disabled global gravity.

> What is the expected output? What do you see instead?

I expected the ball to never penetrate the (which Box2D did as of r146). About 
0.1% of the time, it will tunnel through the shape, bounce around the inside, 
and bounce out. At 30fps with restitution = 0.5, I hit that case in about five 
seconds due to the multiple bounces. I think it is passing through the 
vertices, but I'm not sure. It is definitely a precision issue caused by the 
new compiler.

Objects also take much longer to fall asleep, making many micro-collisions.

> What version of the product are you using? On what operating system?
Box2D from SVN as of Jan 24 2015 (r154  ). Under Chrome and Safari on OS X.

In Box2D/Build/google/makefile, this line:
svn checkout http://closure-library.googlecode.com/svn/trunk/ 
$(GOOGLE_PATH)/closure-library

... should be changed to:
git clone https://github.com/google/closure-library.git 
$(GOOGLE_PATH)/closure-library

What steps will reproduce the problem?
1. Setup two block in stack
2. Change top blocks fixture filter to disable collisions between blocks.

What is the expected output? What do you see instead?
After that top block must fall down, but it is not.

What version of the product are you using? On what operating system?
Mac Os in firefox

Please provide any additional information below.
I fixed it.
The problem was in 
box2d.b2Fixture.prototype.Refilter = function ()
{
    if (this.m_body)
    {
        return;
    }
        ...
}

wront in:
if (this.m_body)

must be
if (!this.m_body)

I'm converting some of my code from box2dweb to box2d-html5 so I can make use 
of all joints etc. Thanks for all your work on this!

I noticed one scene I had was giving quite different behavior to box2dweb, as 
shown in this video: http://youtu.be/17G7NsyqgsY

This tower should hold together reasonably well for a few seconds, and then 
start to crumble from the outside, with a large internal collapse after that. 
With box2d-html5 it appears that all parts of the tower collapse right away. 
Any ideas about what might be causing this? It's interesting that the bottom 
row of dominos does not have this problem (where one side of the contact is a 
static body).

Source code for the domino tower is attached.