A query on game update and render

General Discussions
#1

Hi,

I am learning lwjgl now a days.
My query is that as in our game loop we call update on entities and then call render(which renders/draws the entity on screen)
then why does FPS(frame per second) parameter impacts our game, as we are manually calling render from our game loop.
As far as I understand, FPS determines the rate at which entities are drawn/rendered by graphics engine of game,but as we are
ouselves calling render method then it means for every update there is a render, so why is FPS so important
and so much heavily figures in game related documents, articles etc?
Please clarify.

#2

FPS stands for frames per second, and is a measurement of how fast a computer can run a certain game. In simple games the update and rendering speed are tied together, as in update, render, update, render, and so on. Let’s say we limit our game speed to 50 updates per second. This means that 1. the game cannot be rendered at a higher frame-rate than the game is updated, because an update is followed by rendering, meaning that the game cannot render at any higher than 50 FPS, and 2. that if the rendering of the game (which is usually heavier than updating) starts taking too long time the whole game will run slower. It will not just stutter, it will actually run slower, which is often undesired. It’s better to not render each frame in this case and instead focus on updating so the game actually runs at normal speed.

For a better explanation see the excellent game loop tutorial here: http://www.java-gaming.org/topics/game-loops/24220/view.html.

To summarize: You often want your game to render at a rate that is independent to the updating rate.

#3

I sense deja vu on the question.