MDN URL

https://developer.mozilla.org/en-US/docs/Web/API/WebGL_API/Matrix_math_for_the_web

What specific section or headline is this issue about?

Rotation matrix

What information was incorrect, unhelpful, or incomplete?

const transformedPoint = [
  Math.cos(rotationInRadians) * distance,
  Math.sin(rotationInRadians) * distance,
];

The code above calculating transformed point misses the original point angle.

What did you expect to see?

In this case, the original point angle should be preserved.

const originalAngleInRadians = Math.atan2(point[1], point[0]);
const transformedPoint = [
  Math.cos(originalAngleInRadians + rotationInRadians) * distance,
  Math.sin(originalAngleInRadians + rotationInRadians) * distance,
];

Do you have any supporting links, references, or citations?

No response

Do you have anything more you want to share?

No response

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