@phaserjs/phaser/components/transform/MultiplyLocalWithWorld.js

Phaser 4

import { TRANSFORM, Transform2DComponent } from "./Transform2DComponent";
export function MultiplyLocalWithWorld(parentID, childID) {
  const parentData = Transform2DComponent.data[parentID];
  const childData = Transform2DComponent.data[childID];
  const pa = parentData[TRANSFORM.WORLD_A];
  const pb = parentData[TRANSFORM.WORLD_B];
  const pc = parentData[TRANSFORM.WORLD_C];
  const pd = parentData[TRANSFORM.WORLD_D];
  const ptx = parentData[TRANSFORM.WORLD_TX];
  const pty = parentData[TRANSFORM.WORLD_TY];
  const a = childData[TRANSFORM.LOCAL_A];
  const b = childData[TRANSFORM.LOCAL_B];
  const c = childData[TRANSFORM.LOCAL_C];
  const d = childData[TRANSFORM.LOCAL_D];
  const tx = childData[TRANSFORM.LOCAL_TX];
  const ty = childData[TRANSFORM.LOCAL_TY];
  childData[TRANSFORM.WORLD_A] = a * pa + b * pc;
  childData[TRANSFORM.WORLD_B] = a * pb + b * pd;
  childData[TRANSFORM.WORLD_C] = c * pa + d * pc;
  childData[TRANSFORM.WORLD_D] = c * pb + d * pd;
  childData[TRANSFORM.WORLD_TX] = tx * pa + ty * pc + ptx;
  childData[TRANSFORM.WORLD_TY] = tx * pb + ty * pd + pty;
}