Fast objects are blurred

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kindinger

Hi. I am doing an endless runner game with random obstacles. The thing is, when the background and the obstacles move fast enough they get all blurred, with ghosts.
The background is a scene built with tilesets and some sprites for the torches.
The obstacles are scenes with sprites for the spikes a collision shape.
The player don't move, only jumps, is the background and the obstacles that move in the x position using * delta in _process().
I am attaching two gifs, one in slow speed (less perceptible) and one in faster speed. Also a screen capture while frozen so you can know how it should look. And my node tree.
Background and obstacles (traps) are instantiated via code inside their respective nodes.
I don't think the problem is with my monitor, since it happens with other monitors, all 60hz.
I appreciate any help!

cybereality

It's probably just your monitor. Well, actually your eyes too, but it's complicated. LCD monitors work on sample and hold. Meaning a full image is shown, then held (typically for 1/60th of a second), then the next image is shown. But your brain's vision works continuously. So it assumes the motion is going to be smooth (no one knows how smooth the vision system is, but some speculate it it's above 1,000Hz). So your brain actually generates the ghost in the space between where the object is on screen and where it should be.

In addition, LCD monitors cannot switch their pixels instantly. This is called switching time or response time, and is typically measured around 1ms. However, this is marketing BS, many monitors can take anywhere from 10ms to 30ms to fully switch (depending on color) which is almost a full frame (at 60Hz) or even longer than a full frame at higher refreshes. This leads to motion blurring or commonly called ghosting. This looks like what is happening.

If your monitor has an overdrive feature, this can help. It works by adjusting the way the pixels switch (to anticipate the next frame) and can reduce the switching time somewhat, and a good implementation can almost eliminate the ghosting. However, a poor implementation can actually cause reverse ghosting. But it is good to check the monitor settings. This can have many names, sometimes it is called game mode, pixel response, overdrive, etc.

Also, if you have G-Sync or FreeSync, that can help with the perceptual ghosting (the first thing I said) but not with switching time ghosting. In either case, if you get a 144Hz monitor with FreeSync and overdrive it is reduced to the point where you really can't notice. But on a 60Hz screen without gaming features, there is probably not much you can do.