@phaserjs/phaser/math/mat4/Mat4LookAt.js

Phaser 4

import { Mat4Identity } from "./Mat4Identity";
import { Matrix4 } from "./Matrix4";
export function Mat4LookAt(eye, center, up, out = new Matrix4()) {
  const { x: eyex, y: eyey, z: eyez } = eye;
  const { x: upx, y: upy, z: upz } = up;
  const { x: centerx, y: centery, z: centerz } = center;
  if (Math.abs(eyex - centerx) < 1e-5 && Math.abs(eyey - centery) < 1e-5 && Math.abs(eyez - centerz) < 1e-5) {
    return Mat4Identity(out);
  }
  let z0 = eyex - centerx;
  let z1 = eyey - centery;
  let z2 = eyez - centerz;
  let len = 1 / Math.hypot(z0, z1, z2);
  z0 *= len;
  z1 *= len;
  z2 *= len;
  let x0 = upy * z2 - upz * z1;
  let x1 = upz * z0 - upx * z2;
  let x2 = upx * z1 - upy * z0;
  len = Math.hypot(x0, x1, x2);
  if (!len) {
    x0 = 0;
    x1 = 0;
    x2 = 0;
  } else {
    len = 1 / len;
    x0 *= len;
    x1 *= len;
    x2 *= len;
  }
  let y0 = z1 * x2 - z2 * x1;
  let y1 = z2 * x0 - z0 * x2;
  let y2 = z0 * x1 - z1 * x0;
  len = Math.hypot(y0, y1, y2);
  if (!len) {
    y0 = 0;
    y1 = 0;
    y2 = 0;
  } else {
    len = 1 / len;
    y0 *= len;
    y1 *= len;
    y2 *= len;
  }
  return out.set(x0, y0, z0, 0, x1, y1, z1, 0, x2, y2, z2, 0, -(x0 * eyex + x1 * eyey + x2 * eyez), -(y0 * eyex + y1 * eyey + y2 * eyez), -(z0 * eyex + z1 * eyey + z2 * eyez), 1);
}