Maes
I like big butts!
Posts: 8662
Registered: 07-06 |
Planky said:
It worked fine, but it ran like it was in slow motion . Remember thinking it didnt look like low frame-rate.
Some games (like Doom) can skip rendering a frame to the screen if necessary, while the actual game engine gets preferential use of the CPU's time and strives to always keep close to the target rhythm, with no skipping.
If there's barely enough processing power to run the engine at 35 fps, the game will still run in real time (if you switch to the automap) but you will get very sparse screen updates. By giving a bit more CPU power you will slowly "upgrade" from a sparse slideshow to a low-fps situation, to a jerky 10-15 fps, to a somewhat playable 15-20, to a smooth 20 and above, while keeping real-time sync. It all depends on whether you have enough "CPU horsepower" to at least run the engine at the target 35 fps and enough to spare for decent video output (this ratio is generally 50:50, and rendering complexity is often correlated to map complexity)
Other games throttle down their target frame rate e.g. from 70 fps to 35 to 17.5 fps or some other fixed amount, or start skipping every other frame, every two other frames etc. if they detect they can't keep up, and throttle up as soon as possible.
Of course, at a certain point you may simply not have enough CPU horsepower to run even the game engine at the target speed (e.g. imagine running NUTS.WAD on a 386, even without any video output). In that case, unless the skipping can affect the game engine itself (it can, in some poorly coded games), you will see actual slowdown and slow motion.
Some games (like most classic 2D arcade games) are not designed to skip frames at all: the engine and video output are always synced and in a CPU-heavy situation both will slow down. This is easy to see in e.g. Bubble Bobble, in the Raiden shooters, in many Danmaku games and even in the Metal Slug games on the Neo-Geo. In those games, losing frames would mean not seeing an object move (e.g. a bullet) so it makes sense to draw everything.
Last edited by Maes on 01-24-12 at 12:52
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01-19-12 19:07 
