Making things collide

A huge part of the physics system is making things collide. We need to figure out whether the objects have collided and pass on the relevant information. In this recipe, we will look at different techniques to do this.

Getting ready

You need a Windows machine and a working copy of Visual Studio. No other prerequisites are required.

How to do it…

In this recipe, we will find out how easy it is to detect collisions:

#include <Box2D/Collision/b2Collision.h>
#include <Box2D/Collision/Shapes/b2PolygonShape.h>

// Find the max separation between poly1 and poly2 using edge normals from poly1.
static float32 b2FindMaxSeparation(int32* edgeIndex,
             const b2PolygonShape* poly1, const b2Transform& xf1,
             const b2PolygonShape* poly2, const b2Transform& xf2)
{
  int32 count1 = poly1->m_count;
  int32 count2 = poly2->m_count;
  const b2Vec2* n1s = poly1->m_normals;
  const b2Vec2* v1s = poly1->m_vertices;
  const b2Vec2* v2s = poly2...