如何在Actionscript 2.0中使一個簡單的彈跳球在牆壁上反彈

Question

對我來說這似乎很簡單，但是我的解決方案不起作用。我製作了一個小程序，這是我的最大和最先進的程序，但仍然是一個小程序。它只是一個從地面反彈並慢慢耗盡能量的球。我可以通過按下SPACE重新啓動彈跳功能，它可以通過按下箭頭鍵來改變方向，使用非常簡單的速度計算（實際上非​​常簡單）。

這是我的問題，我對編程非常陌生，這只是我的第二天，而且我需要一種方法將球從舞臺的側壁彈出。

onClipEvent(load){ 
velocity = 0 //Vertical Velocity, is increased and decreased by the effects of gravity and bouncing with SPACE 
sideVel =0 //Side Velocity, increases when the arrow keys are pressed, decreases over time 
gravity = 2 //Gravity, constant force that never changes 
} 
onClipEvent(enterFrame){ 
_x += sideVel //Moves the ball the value of Side Velocity 
if (Key.isDown(Key.LEFT)) { 
    sideVel -= 2 //Technically decreases Side Velocity, but really increases it in another direction 
} 
else { 
    if(sideVel<0) { //If the button isn't being pressed Side Velocity returns to 0 over time 
    sideVel += 1 
    } 
} 
if (Key.isDown(Key.RIGHT)) { 
    sideVel += 2 //Increases Side Velocity 
} 
else { 
    if(sideVel>0) //If the button isn't being pressed Side Velocity returns to 0 over time 
    sideVel -= 1 
} 
if (sideVel < -20){ //Side Velocity isn't allowed to go below this number 
    sideVel +=2 //So we add 2 
} 
if (sideVel > 20) { //Same as above 
    sideVel -=2 
} 
velocity += gravity //Regular Velocity increases by 2 every frame 
_y += velocity //mcMain moves at the speed of its velocity 
if(_y>=Stage.height){ 
if(Key.isDown(Key.SPACE)){ 
    velocity=-28 //Sets Velocity to -28, pretty much the same as doing a jump 
} 
else { 
_y = Stage.height 
velocity *= -0.9 //Reverses mcMain's velocity, so it bounces back into the air at a slightly slower speed 
} 
/*Here's the problem 
if(_x>=Stage.width - 25){ 
    _x=Stage.width - 25 
sideVel *= -1 
} 
if(_x<=Stage.width - 550){ 
    _x=Stage.width - 550 
sideVel *= -1 
} 
} 
} 

Answer 1

你必須手動更改時，它打在牆上，這樣的碰撞不註冊多次的MC（MC.x++和諸如此類的東西）的位置。此外，使用while陳述代替if作爲牆壁碰撞將確保球不通過牆壁。