Box2D的靜態物體摩擦

Question

我創建一個地面體是這樣的：

// Define the ground body. 
    b2BodyDef groundBodyDef; 
    groundBodyDef.position.Set(0, 0); // bottom-left corner 

    // Call the body factory which allocates memory for the ground body 
    // from a pool and creates the ground box shape (also from a pool). 
    // The body is also added to the world. 
    b2Body* groundBody = world->CreateBody(&groundBodyDef); 

    // Define the ground box shape. 
    b2PolygonShape groundBox; 

    // bottom 
    groundBox.SetAsEdge(b2Vec2(0,0), b2Vec2(screenSize.width/PTM_RATIO,0)); 
    groundBody->CreateFixture(&groundBox,0); 

    // top 
    groundBox.SetAsEdge(b2Vec2(0,screenSize.height/PTM_RATIO), b2Vec2(screenSize.width/PTM_RATIO,screenSize.height/PTM_RATIO)); 
    groundBody->CreateFixture(&groundBox,0); 

    // left 
    groundBox.SetAsEdge(b2Vec2(0,screenSize.height/PTM_RATIO), b2Vec2(0,0)); 
    groundBody->CreateFixture(&groundBox,0); 

    // right 
    groundBox.SetAsEdge(b2Vec2(screenSize.width/PTM_RATIO,screenSize.height/PTM_RATIO), b2Vec2(screenSize.width/PTM_RATIO,0)); 
    groundBody->CreateFixture(&groundBox,0); 

如何設置它的摩擦？ 謝謝。

Answer 1

您需要從夾具定義（b2FixtureDef）創建夾具，您可以在其中設置特定的摩擦力。事情是這樣的：

b2FixtureDef fixtureDef; 

fixtureDef.shape = &groundBox; 
fixtureDef.density = 0.0f; 
fixtureDef.friction = YOUR_FRICTION_VALUE; 

groundBody->CreateFixture(&fixtureDef);