cocos2d-iphone - 如何设置为等速速度？ (Cocos2d-x)

Question

如何设置速度恒定

spriteBody->setVelocity(Vec2(100,300)); 一段时间后速度就会变慢

Answer 1

有很多解决方案可以满足您的需求。您可以使用操作移动:

auto action = MoveBy::create (duration, Vec2(100,300));
spriteBody->runAction (action);

当您想稍后停止时:

sprite->stopAction (action);

您可以在更新功能中手动控制速度:

void update (float dt)
{
    //slow down speed
    //velocityVector is a Vec2 of velocity
    //slowAmount is a float which contains amount to slow in 1 second
    unitVector = velocityVector;
    unitVector.normalise();
    velocityVector -= unitVector *  slowAmount * dt;

    //adjust position
    sprite->setPosition (getPosition () + velocityVector * dt);
}

或者你可以使用物理体:

sprite->getPhysicsBody()->applyForce(Vec2(100, 300));

如果你想让物理体减速，请设置物理体 Material 的摩擦力

auto material = PHYSICSBODY_MATERIAL_DEFAULT; 
material.density = 1.0f;
material.restitution = 0.7f;
material.friction = 0.5f; //set friction here
sprite->setPhysicsBody(PhysicsBody::createBox(sprite->getContentSize(), material));

有关如何处理物理和设置的更多详细信息: http://www.cocos2d-x.org/wiki/Physics