Box2d沒有力量的邊界框

Question

目前，Cocos2d-Box2d項目正在使用b2Vec2爲遊戲邊緣創建邊界框。正因爲如此，邊界框不會影響運動物體，它是不受力影響的物體（意味着物體通常會飛離屏幕）。我試圖看看是否有辦法讓運動體與屏幕連接。如果沒有，我會很感激，如果有人向我解釋我應該如何在屏幕的角落製造一個帶有靜態物體的邊框。

Answer 1

下面是兩種方法...嘗試任何一個

//方法 - 1

b2BodyDef groundBodyDef; 
groundBodyDef.position.Set(0, 0); 
b2Body    *mGroundBody ; 


mGroundBody = self.world->CreateBody(&groundBodyDef); 
NSString *strId = @"Ground Body"; 
mGroundBody->SetUserData(strId); 

b2EdgeShape groundBox;  

    //bottom 
    groundBox.Set(b2Vec2(0.0f,0.0f), b2Vec2(mS.width/PTM_RATIO,0.0f)); 
    mGroundBody->CreateFixture(&groundBox,0); 

    // top 
    groundBox.Set(b2Vec2(0,mS.height/PTM_RATIO), b2Vec2(mS.width/PTM_RATIO, mS.height/PTM_RATIO)); 
    mGroundBody->CreateFixture(&groundBox,0); 


    // left 
    groundBox.Set(b2Vec2(0,mS.height/PTM_RATIO), b2Vec2(0,0)); 
    mGroundBody->CreateFixture(&groundBox,0); 

    // right 
    groundBox.Set(b2Vec2(mS.width/PTM_RATIO,mS.height/PTM_RATIO), b2Vec2(mS.width/PTM_RATIO,0)); 
    mGroundBody->CreateFixture(&groundBox,0); 

//方法 - 2

//create 4 box2d walls... 

    float bW = (IS_IPAD) ? (8) : 2 ; 
    //top 
    { 
     b2BodyDef bodyDef; 
     bodyDef.type = b2_staticBody; 
     bodyDef.position.Set((mS.width*0.5f)/PTM_RATIO, (mS.height)/PTM_RATIO); 
     bodyDef.linearDamping = 0.0f; 
     bodyDef.angularDamping = 0.0f; 

     bodyDef.userData = strId ; 

     b2PolygonShape box; 
     box.SetAsBox(((mS.width*0.5f)/PTM_RATIO), (bW)/PTM_RATIO); 

     b2FixtureDef fixDef; 
     fixDef.shape = &box; 
     fixDef.density = 1.0f; 
     fixDef.friction = 0.1f; 
     fixDef.restitution = 1.0f; 
     fixDef.isSensor = false; 

     b2Body *topBody = self.world->CreateBody(&bodyDef); 
     topBody->CreateFixture(&fixDef); 

    } 

    //bottom 
    { 
     b2BodyDef bodyDef; 
     bodyDef.type = b2_staticBody; 
     bodyDef.position.Set((mS.width*0.5f)/PTM_RATIO, 0); 
     bodyDef.linearDamping = 0.0f; 
     bodyDef.angularDamping = 0.0f; 

     bodyDef.userData = strId ; 

     b2PolygonShape box; 
     box.SetAsBox(((mS.width*0.5f)/PTM_RATIO), (bW)/PTM_RATIO); 

     b2FixtureDef fixDef; 
     fixDef.shape = &box; 
     fixDef.density = 1.0f; 
     fixDef.friction = 0.1f; 
     fixDef.restitution = 1.0f; 
     fixDef.isSensor = false; 

     b2Body *topBody = self.world->CreateBody(&bodyDef); 
     topBody->CreateFixture(&fixDef); 

    } 

    //left 
    { 
     b2BodyDef bodyDef; 
     bodyDef.type = b2_staticBody; 
     bodyDef.position.Set(0, (mS.height*0.5f)/PTM_RATIO); 
     bodyDef.linearDamping = 0.0f; 
     bodyDef.angularDamping = 0.0f; 

     bodyDef.userData = strId ; 

     b2PolygonShape box; 
     box.SetAsBox(((bW)/PTM_RATIO), (mS.height*0.5f)/PTM_RATIO); 

     b2FixtureDef fixDef; 
     fixDef.shape = &box; 
     fixDef.density = 1.0f; 
     fixDef.friction = 0.1f; 
     fixDef.restitution = 1.0f; 
     fixDef.isSensor = false; 

     b2Body *topBody = self.world->CreateBody(&bodyDef); 
     topBody->CreateFixture(&fixDef); 

    } 

    //right 
    { 
     b2BodyDef bodyDef; 
     bodyDef.type = b2_staticBody; 
     bodyDef.position.Set((mS.width)/PTM_RATIO, (mS.height*0.5f)/PTM_RATIO); 
     bodyDef.linearDamping = 0.0f; 
     bodyDef.angularDamping = 0.0f; 

     bodyDef.userData = strId ; 

     b2PolygonShape box; 
     box.SetAsBox(((bW)/PTM_RATIO), (mS.height*0.5f)/PTM_RATIO); 

     b2FixtureDef fixDef; 
     fixDef.shape = &box; 
     fixDef.density = 1.0f; 
     fixDef.friction = 0.1f; 
     fixDef.restitution = 1.0f; 
     fixDef.isSensor = false; 

     b2Body *topBody = self.world->CreateBody(&bodyDef); 
     topBody->CreateFixture(&fixDef); 
    }