AI跟随并避免与障碍物碰撞

Question

AI跟随并避免与障碍物碰撞

javascriptalgorithmmathartificial-intelligencepath-finding

3

我正在制作一个基于极坐标的AI导航系统。目的是将角色移动到一个位置，同时避开其路径上的可能障碍。

这段代码大部分时间都能正常工作，但在测试后我发现：当玩家、障碍和角色在X或Y方向或对角线上完全对齐时，角色会卡在障碍物里。当玩家“贴着”墙壁行走时特别容易注意到，因为角色的运动向量会被墙壁裁剪，使它们保持对齐状态。

点击代码片段中的按钮查看详细情况。

有没有办法防止这种情况发生？

const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');

let playerX = 100;
let playerY = 200;

let obstacleX = 200;
let obstacleY = 200;

let actorX = 300;
let actorY = 201;


function loop() {
    // Wall clipping
    if (actorX > 490) {
        actorX = 490;
    } else if (actorX < 10) {
        actorX = 10;
    }

    if (actorY > 490) {
        actorY = 490;
    } else if (actorY < 10) {
        actorY = 10;
    }

    // Vector between player and actor
    let vectorPlayerX = playerX - actorX;
    let vectorPlayerY = playerY - actorY;

    // Vector between obstacle and actor
    let vectorObstacleX = obstacleX - actorX;
    let vectorObstacleY = obstacleY - actorY;

    // Where to move, defaults to player's position
    const anglePlayer = Math.atan2(vectorPlayerY, vectorPlayerX);
    let moveAngle = anglePlayer;

    // If near obstacle, adjust course and try to avoid it
    if (Math.sqrt(vectorObstacleX * vectorObstacleX + vectorObstacleY * vectorObstacleY) < 50) {
        const angleObstacle = Math.atan2(vectorObstacleY, vectorObstacleX);
        moveAngle += anglePlayer - angleObstacle;
    }

    // Move the vector to desired location
    actorX += Math.cos(moveAngle);
    actorY += Math.sin(moveAngle);

    //Drawing
    ctx.clearRect(0, 0, 500, 500);

    ctx.beginPath();
    ctx.fillStyle = "gray";
    ctx.arc(actorX, actorY, 10, 0, Math.PI * 2, true);
    ctx.fill();

    ctx.beginPath();
    ctx.fillStyle = "orange";
    ctx.arc(obstacleX, obstacleY, 10, 0, Math.PI * 2, true);
    ctx.fill();

    ctx.beginPath();
    ctx.fillStyle = "blue";
    ctx.arc(playerX, playerY, 10, 0, Math.PI * 2, true);
    ctx.fill();

    requestAnimationFrame(loop);
}

requestAnimationFrame(loop);


function nonAligned() {
    playerX = 100;
    playerY = 200;

    obstacleX = 200;
    obstacleY = 200;

    actorX = 300;
    actorY = 201;
}

function alignedY() {
    playerX = 100;
    playerY = 490;

    obstacleX = 200;
    obstacleY = 490;

    actorX = 300;
    actorY = 490;
}

function alignedBoth() {
    playerX = 200;
    playerY = 200;

    obstacleX = 300;
    obstacleY = 300;

    actorX = 400;
    actorY = 400;
}

#options {
    position: fixed;
    top: 5px;
    left: 5px;
}

<!DOCTYPE html>
<html>
<body>
    <canvas id="canvas" width="500" height="500"></canvas>
<div id="options">
    <button onclick="nonAligned()">Spawn non-aligned</button>
    <button onclick="alignedY()">Spawn Y aligned</button>
    <button onclick="alignedBoth()">Spawn diagonally aligned</button>
</div>
</body>
</html>

- Will Pierce

1

角度是棘手的。如果可以的话，总是使用向量来工作。 - meowgoesthedog

@meowgoesthedog 我曾经通过获取演员和玩家之间的大小，然后将其朝向玩家移动并远离障碍物（如果足够接近）来实现这一点。可能更有效率，因为它不使用Math.atan2、cos和sin。但我遇到了问题，因为由于障碍物给出的负力，演员的速度会减慢。 - Will Pierce

如果一个问题可以在极坐标系下解决，那么它也可以在笛卡尔坐标系下解决（甚至更容易）；使用笛卡尔坐标系的主要优势是你不必处理在正负180度处的坐标奇点（即向量数学具有旋转不变性）。请发布您原来基于向量的代码。 - meowgoesthedog

嘿！我在这里发帖只是因为这很酷，而且由于你��在研究 AI 导航，所以应该了解这存在。虚幻引擎有 unreal.js。您可以只使用 JavaScript 使用 Unreal 及其 AI 系统以及所有其他强大功能: https://github.com/ncsoft/Unreal.js/ - Max Baldwin

2个回答

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Surt · Answer 1

如果玩家和障碍物之间的角度相同，则我们继续前进，因为变量会互相抵消。

    moveAngle += anglePlayer - angleObstacle;

如果 anglePlayer 是 117，angleObstacle 是 117 并且你的 moveAngle 也是 117，则您会得到：

   117 + 117 -117 = 117 ...

您可能需要类似这样的内容（伪代码）：

    moveAngle += anglePlayer + random(90)-45;

或者如果遇到障碍物，向左或向右移动

    moveAngle += anglePlayer - 90;
    if (random(2)==1 moveAngle += 180

- jwimberley · Answer 2

问题确实是当moveAngle直接指向障碍物时没有改变。一个小修改可以检查moveAngle是从障碍物顺时针还是逆时针旋转，并进一步远离（注意：我的代码在这个原因上打破了贴墙行走并且在“Y轴对齐”情况下表现不佳，但这是可以修复的，只是我不想修复）。

const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');

let playerX = 100;
let playerY = 200;

let obstacleX = 200;
let obstacleY = 200;

let actorX = 300;
let actorY = 201;


function loop() {
    // Wall clipping
    if (actorX > 490) {
        actorX = 490;
    } else if (actorX < 10) {
        actorX = 10;
    }

    if (actorY > 490) {
        actorY = 490;
    } else if (actorY < 10) {
        actorY = 10;
    }

    // Vector between player and actor
    let vectorPlayerX = playerX - actorX;
    let vectorPlayerY = playerY - actorY;

    // Vector between obstacle and actor
    let vectorObstacleX = obstacleX - actorX;
    let vectorObstacleY = obstacleY - actorY;

    // Where to move, defaults to player's position
    const anglePlayer = Math.atan2(vectorPlayerY, vectorPlayerX);
    let moveAngle = anglePlayer;

    // If near obstacle, adjust course and try to avoid it
    obs_distance = Math.sqrt(vectorObstacleX * vectorObstacleX + vectorObstacleY * vectorObstacleY);
    if (obs_distance < 100) {
        const angleObstacle = Math.atan2(vectorObstacleY, vectorObstacleX);
        delta = Math.PI/2.0;
        if (obs_distance > 100.0/32.0) { delta = (100.0/32.0)*Math.PI/obs_distance; }
        cross = Math.sin(moveAngle-angleObstacle);
        if (cross>0) { moveAngle += delta; }
        if (cross<0) { moveAngle -= delta; }
        if (cross==0) {
           if (Math.random(2)==1) {
             moveAngle += delta;
           } else {
             moveAngle -= delta;
           }
        }
    }

    // Move the vector to desired location
    actorX += Math.cos(moveAngle);
    actorY += Math.sin(moveAngle);

    //Drawing
    ctx.clearRect(0, 0, 500, 500);

    ctx.beginPath();
    ctx.fillStyle = "gray";
    ctx.arc(actorX, actorY, 10, 0, Math.PI * 2, true);
    ctx.fill();

    ctx.beginPath();
    ctx.fillStyle = "orange";
    ctx.arc(obstacleX, obstacleY, 10, 0, Math.PI * 2, true);
    ctx.fill();

    ctx.beginPath();
    ctx.fillStyle = "blue";
    ctx.arc(playerX, playerY, 10, 0, Math.PI * 2, true);
    ctx.fill();

    requestAnimationFrame(loop);
}

requestAnimationFrame(loop);


function nonAligned() {
    playerX = 100;
    playerY = 200;

    obstacleX = 200;
    obstacleY = 200;

    actorX = 300;
    actorY = 201;
}

function alignedY() {
    playerX = 100;
    playerY = 490;

    obstacleX = 200;
    obstacleY = 490;

    actorX = 300;
    actorY = 490;
}

function alignedBoth() {
    playerX = 200;
    playerY = 200;

    obstacleX = 300;
    obstacleY = 300;

    actorX = 400;
    actorY = 400;
}

#options {
    position: fixed;
    top: 5px;
    left: 5px;
}

<!DOCTYPE html>
<html>
<body>
    <canvas id="canvas" width="500" height="500"></canvas>
<div id="options">
    <button onclick="nonAligned()">Spawn non-aligned</button>
    <button onclick="alignedY()">Spawn Y aligned</button>
    <button onclick="alignedBoth()">Spawn diagonally aligned</button>
</div>
</body>
</html>