[Box2D] Detect collision between two b2Bodies

cocos2d-x C++
#1

I created two b2Bodies with b2BodyFixtureDef:

//Def1
BodyAFixtureDef.filter.categoryBits = 0x0001;
BodyAFixtureDef.filter.maskBits = 0x0001;
//Def2
BodyBFixtureDef.filter.categoryBits = 0x0002;
BodyBFixtureDef.filter.maskBits = 0x0002;

then create two bodies with them:

How to Detect collision between two b2Bodies, that has a different categoryBits and maskBits index to other?
many thanks!

#2

They won’t collide because of the bit masks you’ve set.

the mask bits tell the engine what categories to collide with

As 0x0001 AND 0x0002 == 0x0000 there will be no collision

Set the mask to 0x0003 on them to make them collide

#3

@Maxxx thanks for rep!
I want them to get through to each other, but able to detect when bodyA comes into bodyB’s position. how could I do that?
sorry my english so bad

#4

i think what you’re looking for is sensor fixtures … Here take a read.

#5

Joseph beat me to it - and he’s right. A sensor detects collisions but doesn’t act on them - so setting the IsSensor property to true, and the bitmasks so that they will collide, will give you what you’re after.

#6

Its what I’m looking for. thanks! :slight_smile: