Rotate what now? Aks, what are you talking about?

I wanted to write down how I made the enemy characters in Artificial Rage rotate towards the player,
since I couldn’t find a simple answer.

Most things I found was math. Now math is fun and good, but when you’re tired
and want to get one thing just to work at 4 am, it’s not gonna help you.

Especially since I’ve never learned linear algebra at any school I’ve went to (or I just likely don’t remember),
and double especially since all the math lingo is in English and I have no idea what any of it means!!!

Getting Gooder at math is on my eternal to-do list, but anyhow, for those like me
who just need to get something done, here’s how I did it.

First off, I just wanted the character to rotate around it’s Y-axis: If you would
stick a.. well stick in a grape and twirl the stick in your fingers, that’s the Y-axis of the grape.
This means the following snippet does not take account the other axises. But I’m sure it could be used for it.

Code dump incoming:

// C99 code
void Actor_RotateTowards(Actor_Data* actor, Vector3 targetPosition)
{
    // Rotates the actor around Y axis
    Vector3 diff        = Vector3Subtract(actor->position, targetPosition);
    float y_angle       = -(atan2(diff.z, diff.x) + PI / 2.0);
    Vector3 newRotation = (Vector3) { 0, y_angle, 0 };

    // Use quaternion slerping for smoother rotation, so the actor always follows the shortest path
    Quaternion start = QuaternionFromEuler(actor->rotation.z, actor->rotat