Box2D Forums

b2World *world;
b2BodyDef bd;
b2Body* obstacles;
b2EdgeShape shape;

obstacles = world->CreateBody(&bd);

for (i=0;i<x;i++)
 {
  fscanf(in,"%d %d %d %d\n",&x0,&y0,&x1,&y1);
  shape.Set(b2Vec2((float)x0*size_scale_factor_x, (float)y0*size_scale_factor_y), b2Vec2((float)x1*size_scale_factor_x, (float)y1*size_scale_factor_y));
  obstacles->CreateFixture(&shape, 0.0f);
 }

world->DestroyBody(obstacles);
obstacles = NULL;
obstacles = world->CreateBody(&bd);

for (i=0;i<x;i++)
 {
  fscanf(in,"%d %d %d %d\n",&x0,&y0,&x1,&y1);
  shape.Set(b2Vec2((float)x0*size_scale_factor_x, (float)y0*size_scale_factor_y), b2Vec2((float)x1*size_scale_factor_x, (float)y1*size_scale_factor_y));
  obstacles->CreateFixture(&shape, 0.0f);
 }

#include <conio.h>
#include <vector>
#include <time.h>
#include <Box2D/Box2D.h>

b2World *world;
b2BodyDef bd;
b2Body* obstacles;
b2EdgeShape shape;

b2Body* body;


void main(void)
{
 int i,j;

 b2Vec2 gravity(0.0f, -1.0f);
 world = new b2World(gravity);
 obstacles = world->CreateBody(&bd);
 
 //we setup a plenty of horizontal lines starting at y==0 and we go lower with every step
 for (int i=0;i<5000;i++)
  {
   shape.Set(b2Vec2(-10.0,0.0-(2.0*i)), b2Vec2(10.0,0.0-(2.0*i)));
   obstacles->CreateFixture(&shape, 0.0f);
  }

 //we set up dynamic body
 b2BodyDef myBodyDef;
 myBodyDef.type = b2_dynamicBody;
 myBodyDef.position.Set(0.0,2.0);
 body = world->CreateBody(&myBodyDef);

 //and we add circle fixture
 b2CircleShape circleShape;
 circleShape.m_p.Set(0, 0);
 circleShape.m_radius = 0.5;
 b2FixtureDef myFixtureDef;
 myFixtureDef.shape = &circleShape;
 myFixtureDef.density = 1.0;
 body->CreateFixture(&myFixtureDef);

 //now we simulate until few steps - ball will land on first horizontal lines
 for (int i=0;i<12;i++)
 {
  for (int j=0;j<30;j++) world->Step(0.01, 6, 2);
  printf("%f %f\n",body->GetPosition().x,body->GetPosition().y);
 }

 printf("ball landed... recreating map\n");

 //so we delete obstacles and create new ones:

 world->DestroyBody(obstacles);
 obstacles = NULL;
 obstacles = world->CreateBody(&bd);

 //notice that we start from i==2 now - so ball should have space to continue some falling
 for (int i=2;i<5000;i++)
  {
   shape.Set(b2Vec2(-10.0,0.0-(2.0*i)), b2Vec2(10.0,0.0-(2.0*i)));
   obstacles->CreateFixture(&shape, 0.0f);
  }

 //let's check what happened:
 for (int i=0;i<12;i++)
 {
  for (int j=0;j<30;j++) world->Step(0.01, 6, 2);
  printf("%f %f\n",body->GetPosition().x,body->GetPosition().y);
 }

 delete world;
 printf("done");
 getch();
}