如何让球从画布的两侧反弹？ [英] How do I make a ball bounce off the sides of the canvas?

问题描述

我想在画布的所有四面墙周围制作一个球（椭圆形），当发生这种情况时，我还想在每次弹跳后改变球的颜色和速度（当然是随机的）。 P.S我希望球继续在四面墙周围的画布上弹跳。谢谢你的帮助！



我的尝试：



这个是我试过的代码。它从左到右穿过x轴但不会在从右到左的路上停下来。我也不知道如何让它从顶部和底部反弹

I want to make a ball(an ellipse) bounce around all four walls of the canvas and as this happens I would also like to change the colour of the ball and speed after each bounce(randomly of course). P.S I want the ball to continue bouncing around the canvas off all four walls. Thanks for the help!

What I have tried:

This is the code I have tried. It gets the ball across the x-axis from left to right but doesn't stop on the way back from right to left. I also don't know how to get it to bounce off the top and bottom sides

// The position of the ball
var x = 25;

// How far the ball moves every time
var speed = 3;
 
var draw = function() {
    background(47, 222, 126);
   
    fill(48, 46, 48);
    ellipse(x, 200, 50, 50);
 
    // Moves the ball
    x = x + speed;
    
    if (x > 375) {
        speed = -5;
        
    if (x < 214) {
        speed = 5;
        }
    }
};

推荐答案

你的球在x和x都有速度方向。如果没有，它就会来回走动。水平（仅x）或垂直（仅y）。我们假设你有两个。你上面的例子只会改变'x' - 所以你认为y方向会发生什么？ ？ ？



每当你定义墙的撞击时，你需要考虑物理定律（弹性碰撞：100％动能节能）。



如果垂直墙被击中：

- 水平速度反转100％

- 垂直速度不变



如果击中水平墙：

- 水平速度不变

- 垂直速度反转100％




现在，开始编码。

Your ball has a velocity in both the x and y directions. If it doesn't, it will just go back and forth. Horizontally (x only) or vertically (y only). Let's presume you have both. Your example, above, only changes 'x' - so what do you think will happen in the y direction ? ? ?

Whenever you define an impact with the wall you need to consider the laws of physics (elastic collision: 100% Kinetic Energy conservation).

If the vertical wall is hit:
- the horizontal velocity is reversed 100%
- the vertical velocity is unchanged

If a horizontal wall is hit:
- the horizontal velocity is unchanged
- the vertical velocity is reversed 100%


Now, start coding.

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