Why is the engine frame-rate limited?

[Commando Peach]

It's obvious some people don't understand such a simple concept as Vsync.

Refresh rate is in Hz, which is simply the number of times data is drawn a second.

FPS is the number of individual frames per second.

If they're both the same number, then they have to be synched.

It's not mathematically possible for anything else.

For example, if you have a light bulb flashing at 60 times per second, and another light bulb flashing at 60 times per second, they will both flash at the EXACT same time, otherwise they wouldn't both be operating at 60 times per second....

It's really not that difficult to understand.

Hey, uh... I'm no computer expert here, but I do get what the other guys are trying to say.

I'll use the example that you gave to help clear up some of the confusion here. Think about those two light bulbs again. Just to make it easier to visualize, think about them flashing once per second, sixty times a minute.

They both flash at the same rate (once every second), but assume that light bulb #2 flashes for the first time a half a second after bulb #1 starts. They both continue flashing once every second, but the bulbs are flashing back and forth at a steady rate, not at the same time. Just because they flash the same number of times per minute does NOT assume that they flash at the exact same time.

Bulb #1 flashes at: 0s 1s 2s 3s 4s...
Bulb #2 flashes at: .5s 1.5s 2.5s 3.5s 4.5s...

Vsync would hypothetically hold Bulb #2 until Bulb #1 was ready to flash, and then let them both flash at the same time.

Without VSync, your monitor and the game can refresh at the same rate, but can still be out of phase with each other. Since, like Eigen said, your monitor will refresh pixel by pixel and not all at once, you'll get image tearing when the game is refreshing in a different phase than the monitor. They're going at the same rate, but not starting at the same time without Vsync.

Does this help?