我在JavaScript在画布上多个省略号,我想他们都相互弹开。我试图使用的距离公式,然后改变x和球的y方向上,当距离小于球半径* 2。
这很适合于中一个球,但它并不适用于多球工作这么好,因为它往往会导致可怕的“跳回路”描绘Here
为了解决这个问题,我决心改变球,这取决于它们相互碰撞,其中,以避免跳回路,并让游戏更贴近现实生活中的物理反弹的方式。
如果有一个边侧面碰撞,我要扭转这两个球的X方向,如果有一个从上到下的碰撞,我要扭转这两个球的Y方向。
所以,我计算所有的点,例如,45度和135度,与一个关联度(这是90个点),并将它们相比225度和315度之间,反之亦然所有90点之间。
如果有任何关于圆的边缘与所有其他球中心点点之间的距离小于半径,我想两个球的Y方向逆转。
我重复相同的处理为135度和225度到315度和405度(相当于45)和反向两个球的X方向。
截至目前,我认为应球弹开对方如何我想他们,但他们就是不。他们相互弹开的侧面和顶部,底部,偶尔的角度,但他们往往沾对方的内部,然后换方向。这里是一个video of the output.
下面是顶部比较底部的代码:
// radius is the same for all the balls and is at 25.
let ballToBallDistance = (x1, y1, x2, y2) => {
return Math.sqrt((Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2)));
}
const ballCollisionY = (start, end) => {
for (let i = start; i <= end; i++) {
return ballObjects[0].ballRadius * Math.sin((i * Math.PI / 180));
}
}
const ballCollisionX = (start, end) => {
for (let i = start; i <= end; i++) {
return ballObjects[0].ballRadius * Math.cos((i * Math.PI / 180));
}
}
const upperYBall = {
bounceTopBottom() {
let n = 0;
for (let i = 0; i < ballObjects.length; i++) {
if (ballObjects.length == 1) {
return;
}
if (n == i) {
continue;
}
let yUpXPoint = ballObjects[n].ballXPos - ballCollisionX(45, 135);
let yUpYPoint = ballObjects[n].ballYPos - ballCollisionY(45, 135);
let centerBallX = ballObjects[i].ballXPos;
let centerBallY = ballObjects[i].ballYPos;
let pointDistance = ballToBallDistance(yUpXPoint, yUpYPoint, centerBallX, centerBallY);
if (pointDistance <= 25) {
ballObjects[n].ballMotionY = ballObjects[n].ballMotionY * -1;
}
if (i == ballObjects.length - 1) {
++n;
i = -1;
continue;
}
}
}
}
const lowerYBall = {
bounceBottomTop() {
let n = 0;
for (let i = 0; i < ballObjects.length; i++) {
if (ballObjects.length == 1) {
return;
}
if (n == i) {
continue;
}
let yDownXPoint = ballObjects[n].ballXPos - ballCollisionX(225, 315);
let yDownYPoint = ballObjects[n].ballYPos - ballCollisionY(225, 315);
let centerBallX = ballObjects[i].ballXPos;
let centerBallY = ballObjects[i].ballYPos;
let pointDistance = ballToBallDistance(yDownXPoint, yDownYPoint, centerBallX, centerBallY);
if (pointDistance <= 25) {
ballObjects[n].ballMotionY = ballObjects[n].ballMotionY * -1;
}
if (i == ballObjects.length - 1) {
++n;
i = -1;
continue;
}
}
}
}
我一直坚持这个功能了两个星期。如果任何人有任何见解,以什么我做错了,或许一个解决方案,实现期望的结果,那将是非常赞赏。
我建议你从特殊情况编码到一个更通用的方法进行切换。
当两个球碰撞:
你会需要:
的方法来计算两个球之间的角度:
function ballToBallAngle(ball1,ball2) {
return Math.atan2(ball2.y-ball1.y,ball2.x-ball1.x)
}
的方法来导出从角度法线向量:
function calcNormalFromAngle(angle){
return [
Math.cos(angle),
Math.sin(angle)
]
}
的方法来计算两个向量的点积:
function dotproduct (a, b){
return a.map((x, i) => a[i] * b[i]).reduce((m, n) => m + n)
}
最后一个方法来计算的反弹角。 Read this,它描述了它完美。
因此要将其放到一起,看看下面的代码片段:
let canvas = document.querySelector('canvas')
let ctx = canvas.getContext('2d')
let balls = [
{x:40,y:40,radius:25,vx:4,vy:3},
{x:300,y:300,radius:50,vx:-2,vy:-3},
{x:100,y:220,radius:25,vx:4,vy:-3},
{x:400,y:400,radius:50,vx:-1,vy:-3},
{x:200,y:400,radius:32,vx:2,vy:-3}
]
function tick() {
balls.forEach((ball, index) => {
ball.x += ball.vx
ball.y += ball.vy
//check for x bounds collision
if (ball.x - ball.radius < 0) {
bounceBall(ball, Math.PI)
ball.x = ball.radius
} else if (ball.x + ball.radius > 500) {
bounceBall(ball, 0)
ball.x = 500 - ball.radius
}
//check for y bounds collision
if (ball.y - ball.radius < 0) {
bounceBall(ball, Math.PI / 2)
ball.y = ball.radius
} else if (ball.y + ball.radius > 500) {
bounceBall(ball, -Math.PI / 2)
ball.y = 500 - ball.radius
}
balls.forEach((other_ball, other_index) => {
if (index == other_index)
return
// how many px the balls intersect
let intersection = ball.radius + other_ball.radius - ballToBallDistance(ball, other_ball)
// if its greater than 0, they must be colliding
if (intersection > 0) {
let angle = ballToBallAngle(ball, other_ball)
let normal = calcNormalFromAngle(angle)
bounceBall(ball, angle)
bounceBall(other_ball, angle + Math.PI)
// set positions so that they are not overlapping anymore
ball.x -= normal[0] * intersection / 2
ball.y -= normal[1] * intersection / 2
other_ball.x += normal[0] * intersection / 2
other_ball.y += normal[1] * intersection / 2
}
})
})
render()
requestAnimationFrame(tick)
}
function render() {
ctx.clearRect(0, 0, canvas.width, canvas.height)
balls.forEach(ball => {
ctx.beginPath();
ctx.arc(ball.x, ball.y, ball.radius, 0, 2 * Math.PI);
ctx.stroke();
})
}
function bounceBall(ball, angle) {
let normal = calcNormalFromAngle(angle)
let velocity = [ball.vx, ball.vy]
let ul = dotproduct(velocity, normal) / dotproduct(normal, normal)
let u = [
normal[0] * ul,
normal[1] * ul
]
let w = [
velocity[0] - u[0],
velocity[1] - u[1]
]
let new_velocity = [
w[0] - u[0],
w[1] - u[1]
]
ball.vx = new_velocity[0]
ball.vy = new_velocity[1]
}
function dotproduct(a, b) {
return a.map((x, i) => a[i] * b[i]).reduce((m, n) => m + n)
}
function ballToBallDistance(ball1, ball2) {
return Math.sqrt((Math.pow(ball2.x - ball1.x, 2) + Math.pow(ball2.y - ball1.y, 2)));
}
function ballToBallAngle(ball1, ball2) {
return Math.atan2(ball2.y - ball1.y, ball2.x - ball1.x)
}
function calcNormalFromAngle(angle) {
return [
Math.cos(angle),
Math.sin(angle)
]
}
tick();
body{
background-color: #eee;
}
canvas{
background-color: white;
}
<canvas width="500" height="500"></canvas>