Chipmunk sprite shape collisions arb data, casting data to a class?

cocos2d-x C++
#1

i have many “peg” objects that do not move, and have a method called hit()

...
pegShape->data = this; // pointer to this Peg object
pegShape->collision_type = 2; // Collisions are grouped by types

i also have a ball that can collide with these pegs

...
ballShape->data = this;
ballShape->collision_type = 1; // Collisions are grouped by types

i’ve added a collision handler

cpSpaceAddCollisionHandler(m_pSpace,1,2,&spriteCollision,NULL,NULL,NULL,this);

static int spriteCollision(cpArbiter *arb, cpSpace *space, void *nothing) {
  CP_ARBITER_GET_SHAPES(arb, a, b);
  Peg* shapeDataB = (Peg*) b->data;
  shapeDataB->hit();
}

it crashes with this error Thread 1: EXC_BAD_ACCESS (code=2, address=0xbfffda…

i’m pretty sure my cast is bad. though the object is not NULL.

here is my full Peg class. it just holds a sprite and has a method to hit();

Peg::Peg(CCPoint pos)
{
  sprite = CCSprite::createWithSpriteFrameName("blue");
  Graphics::getInstance().m_pPegSBN->addChild(sprite);
  sprite->autorelease();
  sprite->setPosition(pos);

  float pegRadius = 13.0f; // should be 10

  cpShape *pegShape = cpCircleShapeNew(pachiBoard->m_pSpace->staticBody, pegRadius, cpv(pos.x,pos.y));
  pegShape->e = 0.5; // Elasticity
  pegShape->u = 0.8; // Friction
  pegShape->data = this; // Associate with ths peg
  pegShape->collision_type = 2; // Collisions are grouped by types
  // Add the shape to out space
  cpSpaceAddStaticShape(pachiBoard->m_pSpace, pegShape);

}
void Peg::hit()
{
  CCLog("peg is hit");
}


Screen Shot 2013-02-13 at 6.26.00 PM.png (73.4 KB)


ss0213.png (73.4 KB)