Cocos2d：沿鼠标单击/触摸的方向射击球

Question

与位于布局左上角的球（固定球）一起玩。 当我使用鼠标单击时，我希望用力将球击中并通过鼠标单击。 鼠标单击可以在布局上的任何地方，而不是在球上。 我曾经使用下面的代码中的＃1来工作。 但目前它已损坏。 当我以90度单击球时，它会远离鼠标单击而射击，例如90 + x。 角度偏离了10度左右。

我使用levelhelper2工具集创建了基本关卡，以布局精灵。

    /*--------------- touchEnded ------------------------------------*/
    -(void)touchEnded:(CCTouch *)touch withEvent:(CCTouchEvent *)event
    {
        ball = (LHSprite*)[self childNodeWithName:@"Ri"];
        ball.anchorPoint = ccp(0.5f,0.5f);
        body = [ball box2dBody];
        pos = body->GetPosition();

        CGPoint location = [touch locationInView:[touch view]];
        location = [[CCDirector sharedDirector] convertToGL:location];
        CGPoint shootVector = ccpSub( location, ball.position );


        /*  #1 Tried this first. 
        b2Vec2 force = b2Vec2(shootVector.x ,shootVector.y);
        force.Normalize();
        force *= 1.5f;
        */

        /*  #2 : Try this version  */
        CGFloat shootAngle = ccpToAngle(shootVector);
        float power = 10;
        float x1 =   -1 * CC_RADIANS_TO_DEGREES(cos(shootAngle));
        float y1 =   -1 * CC_RADIANS_TO_DEGREES(sin(shootAngle));
        b2Vec2 force = b2Vec2(x1* power,y1* power);


        body->ApplyLinearImpulse(force, pos, 1);     
    }

Answer 1

您是否希望球不断或加速飞行？ 为了保持恒定的速度，我将尝试使用以下方法：

CCPoint location = touch->getLocation();
CCPoint ballLoc = ball->getPosition();
CCSize winSize = CCDirector::sharedDirector()->getVisibleSize();

float dX = location.x - ballLoc.x;   //delta between touch and ball
float dX = location.y - ballLoc.y;

float c =  sqrtf((dX * dX) + (dY*dY));   //distance with pythagoras
float cmax = sqrtf((winSize.width * winSize.width) + (winSize.height*winSize.height));   //max Distance when clicking in the bottom right corner the distance is max
float r = cmax / c;   //value to multiply distance

float destX = ballLoc.x + r*dX; //destination is ball location + r*delta
float destY = ballLoc.y + r*dY;

projectile->runAction(CCMoveTo::create(2.0, ccp(realX, realY));

可选，您可以根据距离添加持续时间。

我希望这有帮助。