Counting number of fixtures or b2bodies in a particular rectangular area in cocos2dx | Techbirds

In order to make the b2body and attach it to the world,fixtures are added to the b2body(either one fixture or more are attached to a single b2body).For counting the no. of fixtures in a particular defined area,we can use QueryAABB.

in .h file,write;

int count=0; //call back function counting num of fixtures bool ReportFixture(b2Fixture* fixture) { foundBodies.push_back( fixture->GetBody() ); return true;//keep going to find all fixtures in the query area }

in .cpp file,write the following code in the function where to count fixtures:

HelloWorld queryCallback; b2AABB aabb; aabb.lowerBound = b2Vec2(0,0);//define the lower boundary point of the area in which the fixtures to be count aabb.upperBound = b2Vec2(10,10);//upper boundary point of the rectangular area world->QueryAABB( &queryCallback, aabb );//calling the QueryAABB function which internally call the reportfixture call back function defined in the .h file for (int i = 0; i < queryCallback.foundBodies.size(); i++) { count++; } CCLOG(“count=%d”,count);

This count will return the number of fixtures in the rectangular area with for coordinates as following:
b2Vec2(0,0),b2Vec2(10,0),b2Vec2(10,10),b2Vec2(0,10)

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