Encapsulating Box2D C++ two virtually the same functions

Question

I have two functions that are virtually the same with a few small differences in code, one to create a static body and one to create a dynamic body, however if I call both of them it results in a segmentation fault, but I'm not quite sure why as far as I know I'm not trying to redefine any objects (other than bbox which is a box2d * body).

I've tried debugging it it appears the issue is caused by b2FixtureDef but I again Don't know exactly what it is, From looking at the memory somewhere there is an allocation issue as 0xfeeefeee shows up in a dump of the registers.

as long as I only use one its fine but when I use two or more it crashes. if someone could point me in the right direction ( the code is valid 0 errors and 0 warnings so I'm not looking for handouts )

void entity::setAsPlatform(float hx, float hy, b2World world)
{
   b2BodyDef platformDef;
   platformDef.position.Set(bbox_pos.x,bbox_pos.y);
   b2Body * platform = world.CreateBody(&platformDef);
   b2PolygonShape platformShape;
   platformShape.SetAsBox(hx, hy);
   b2FixtureDef platformFixture;
   platformFixture.shape = &platformShape;
   platform->CreateFixture(&platformFixture);
   bbox = platform;
}


void entity::setAsPlayer(float hx, float hy, b2World world)
{
   b2BodyDef platformDef;
   platformDef.position.Set(bbox_pos.x,bbox_pos.y);
   platformDef.type = b2_dynamicBody;
   b2Body * platform = world.CreateBody(&platformDef);
   b2PolygonShape platformShape;
   platformShape.SetAsBox(hx, hy);
   b2FixtureDef platformFixture;
   platformFixture.shape = &platformShape;
   platform->CreateFixture(&platformFixture);
   bbox = platform;
 }

and in main.cpp

entity platform("Platform", 20, 500);
platform.setAsPlatform(2.0f, 50.0f, world);

entity player("Player", 0, 20);
player.setAsPlayer(1.0f,1.0f,world);

Answer 1

Your main problem is that you keep copying and destroying values that you don't mean to destroy.

Let's take for example world

When you call platform.setAsPlatform(2.0f, 50.0f, world); you make a copy of world because setAsPlatform takes a b2World by value.

You probably meant to write

void entity::setAsPlayer(float hx, float hy, b2World &world)

This would take world per reference and not make a copy which is destroyed at the end of the function. So you added your objects to a copy of your world that you then destroyed, so when the object then tries to look up anything in the world that it's in it'll access already freed up memory as the 0xfeeefeee indicates.