javascript - 根据距离和方向计算坐标

Question

这是我方便的方案：

鉴于：

• 这是二维的，无需担心第三轴
• Segment AB，A以及B有x和y坐标
• Side width，到每个角的距离：width / 2
• direction以度为单位（0 向上，90 向右，180 向下等）

如何计算x和y坐标角1-4？

---

const A = {x: 0, y: 0};
const B = {x: 10, y: 0};
const direction = 90;
const width = 10;
const halfWidth = width / 2;

// tried the following one that I found but
// no lock, I assume somethings off with angles
function getCorner(point, angle, length) {
  return {
    x: point.x + Math.cos(angle) * length,
    y: point.y + Math.sin(angle) * length
  };
}

// EXPECTED
// bottom left: {x: 0, y: 5}
// bottom right: {x: 0, y: -5}
// top left: {x: 10, y: 5}
// top right: {x: 10, y: -5}

console.log(
  "bottom left:", 
  getCorner(A, direction - 90, halfWidth)
);
console.log(
  "bottom right:", 
  getCorner(A, direction + 90, halfWidth)
);

console.log("---");

console.log(
  "top left:", 
  getCorner(B, direction - 90, halfWidth)
);
console.log(
  "top right:", 
  getCorner(B, direction + 90, halfWidth)
);

标签： javascript

Answer 1

终于弄明白了，网上有这么多不同的方法，没有一个奏效。反复试验赢得了胜利。

---

const A = {x: 0, y: 0};
const B = {x: 10, y: 0};
const direction = 90;
const width = 10;
const halfWidth = width / 2;

// changed only this function
function getCorner(point, angle, length) {
  angle = angle * (Math.PI / 180);

  return {
    x: point.x + Math.sin(angle) * length,
    y: point.y + Math.cos(angle) * length
  };
}

// EXPECTED
// bottom left: {x: 0, y: 5}
// bottom right: {x: 0, y: -5}
// top left: {x: 10, y: 5}
// top right: {x: 10, y: -5}

console.log(
  "bottom left:", 
  getCorner(A, direction - 90, halfWidth)
);

// here's an error with JS or something, because
// "x: 6.123233995736766e-16" which is
// "0.0000000000000006123233995736766"
console.log(
  "bottom right:", 
  getCorner(A, direction + 90, halfWidth)
);

console.log("---");

console.log(
  "top left:", 
  getCorner(B, direction - 90, halfWidth)
);
console.log(
  "top right:", 
  getCorner(B, direction + 90, halfWidth)
);