"World" vs. "Local" coordinates. Explanation?  

RE: "World" vs. "Local" coordinates. Explanation?

I assume you probably have seen this article, but I thought I should link it in case you hadn't: https://help.prusa3d.com/en/article/object-manipulation-panel_1757#:~:text=Local%20vs%20World%20coordinates,-In%20the%20Advanced&text=The%20local%20coordinate%20system%20is,%2C%20around%20the%20Z%2Daxis.

As an engineer, I do a lot of coordinate shifting so I'll take a stab at an explanation. A local coordinate frame is affixed to every object on the print bed as a little XYZ axis somewhere on the body. If you rotate or move the object, they move or rotate with it. World coordinates, however, are affixed to the bed and don't move. For something like PrusaSlicer where you don't have to find the location of the object based on the coordinates, this doesn't matter much for translation but definitely does for rotation. If I take a box, rotate it 45 degrees, and scale it in X, it will stretch along the bed's X and be distorted.

If instead, I stretch it along the local coordinate X. The box will scale normally along its own individual X rather than distorting. In other words, it achieves the same results as if I had first scaled along X then rotated.

Let me know if this makes sense. I tried to avoid engineer jargon, but after spending long enough in the field we start to not notice it.