Preview is the output, not just a pretty picture
The Preview window is LightBurn's simulation of what it will send to the laser. It is one of the fastest ways to catch a project that looks correct in the editor but will output differently than expected.
What the colors mean
In the normal Preview display, black lines represent cutting/engraving motion and red lines represent traversal moves where the laser travels between operations. You can hide traversal moves when they make the view too busy.
Use the time slider
The time slider lets you inspect the planned sequence. Drag through the job or press Play to watch the simulated motion. This is especially helpful when you want to check whether engraving happens before cutting, whether small internal shapes are processed at a sensible time, or whether the head is making excessive travel moves.
Problems Preview can reveal
- a Fill object that is unexpectedly only an outline,
- an object that is missing because its layer Output is disabled,
