Box2dSandbox/mutltiJoint/creater.cpp

// Basiques
# include <iostream>
# include <cmath>
# include <vector>

// SDL
# include <SDL/SDL.h>
# undef main
# include <SDL/SDL_rotozoom.h>
# include <SDL/SDL_gfxPrimitives.h>

// Box2D
# include <box2d/box2d.h>
# define MULTI 100.0f

// Prototypes
# include "creater.h"

void createBloc( b2World &world, std::vector<b2Body*> &tbody, SDL_Surface* blc, float x, float y )
{
	// Définition
	b2BodyDef bodyDef;
	bodyDef.type = b2_dynamicBody;
	bodyDef.userData.pointer = (uintptr_t) blc;
	bodyDef.position.Set( x, y );

	// Shape
	b2PolygonShape dynamicBox;
	dynamicBox.SetAsBox( (float)blc->w * 2.0f / MULTI / 2 , (float)blc->h * 2.0f / MULTI / 2  );

	// Fixture
	b2FixtureDef fixtureDef;
	fixtureDef.shape = &dynamicBox;
	fixtureDef.density = 1.0f;
	fixtureDef.friction = 0.3f;

	// Push
	tbody.push_back( 0x0 );
	tbody.back() = world.CreateBody(&bodyDef);
	tbody.back()->CreateFixture(&fixtureDef);
}

void link2ByDist( b2World &world, std::vector<b2Body*> &tbody, std::vector<b2Joint*> &tjoint )
{
	if ( tbody.size() < 2 )
		return ;

    b2Vec2 posA, posB;
	b2DistanceJointDef myDistJointDef;

    myDistJointDef.collideConnected = true ;

	myDistJointDef.bodyA = tbody[ tbody.size() - 2];
    myDistJointDef.bodyB = tbody[ tbody.size() - 1];

    posA = myDistJointDef.bodyA->GetPosition();
    posB = myDistJointDef.bodyB->GetPosition();
    myDistJointDef.length = ( posA - posB ).Length() / 2.0f;

    myDistJointDef.stiffness = 4.0f ;
    myDistJointDef.damping = 0.5f ;

    tjoint.push_back( 0x0 );
    tjoint.back() = world.CreateJoint(&myDistJointDef);
}

void link3ByDist( b2World &world, std::vector<b2Body*> &tbody, std::vector<b2Joint*> &tjoint )
{
	if ( tbody.size() < 3 )
		return ;

    b2Vec2 posA, posB;
	b2DistanceJointDef myDistJointDef;

    myDistJointDef.collideConnected = true ;

    myDistJointDef.stiffness = 4.0f ;
    myDistJointDef.damping = 0.5f ;

    // Joint 1
	myDistJointDef.bodyA = tbody[ tbody.size() - 2];
    myDistJointDef.bodyB = tbody[ tbody.size() - 1];

    posA = myDistJointDef.bodyA->GetPosition();
    posB = myDistJointDef.bodyB->GetPosition();
    myDistJointDef.length = ( posA - posB ).Length() / 2.0f;

    tjoint.push_back( 0x0 );
    tjoint.back() = world.CreateJoint(&myDistJointDef);

    // Joint 2
	myDistJointDef.bodyA = tbody[ tbody.size() - 3];
    myDistJointDef.bodyB = tbody[ tbody.size() - 1];

    posA = myDistJointDef.bodyA->GetPosition();
    posB = myDistJointDef.bodyB->GetPosition();
    myDistJointDef.length = ( posA - posB ).Length() / 2.0f;

    tjoint.push_back( 0x0 );
    tjoint.back() = world.CreateJoint(&myDistJointDef);

    // Joint 3
	myDistJointDef.bodyA = tbody[ tbody.size() - 3];
    myDistJointDef.bodyB = tbody[ tbody.size() - 2];

    posA = myDistJointDef.bodyA->GetPosition();
    posB = myDistJointDef.bodyB->GetPosition();
    myDistJointDef.length = ( posA - posB ).Length() / 2.0f;

    tjoint.push_back( 0x0 );
    tjoint.back() = world.CreateJoint(&myDistJointDef);
}