Nekrono said:
True but lets say the game runs at 40 fps, you add in better physics that takes a hit of let's say 10 fps, you're down to 30 now. Better lighting and more light sources let's say will cost you around 5-10 fps, you would be sitting at 20-25 now.
See what I mean? cutting down things does give you more room to work around other stuff.
It's not always the same, and in some cases some things don't even take a performance hit but the principle is the same nonetheless.
Ugh what?
I don't even...
Having your cpu sit idle twiddling it's thumbs because you cut the physics doesn't magically make the gpu any faster at what it's doing meanwhile.
There are also many factors and bottlenecks in what makes a gpu work.
They have a limited fillrate/vram bandwidth, if you go over that amount it will take more cycles to process which bogs things down (the game may be done calculating physics, ai, lighting, geometry for that frame but it has to wait on the vram for example to load/send textures/shadows to the gpu.
Consoles have serious ram/vram bottlenecks, so if you don't design the maps around that things will slow down to a crawl or not work at all.
Same goes for graphics cards on pc with little vram. (try forcing gta 4 or stalker complete mod to run at 1080p with textures maxed on a graphics card with only 512 MB or less vram, it will run out and have to fileswap to your normal ram or HDD, which both have horribly slow bandwidth compared to the vram (hdd especially), so suddenly you are down to 1-2 fps instead of 100, all because the game requires just 5 MB more vram than you have.
Lower res or any setting a bit to bring you just under the 512MB peak usage and suddenly your fps skyrockets back up.
It's not a linear affair at all like you suggest.
Cutting geometry doesn't magically give you more gpu power to spend on lighting.
The only things that are really related are for example textures, resolution and shadow.
Because they are all bottlenecked by the same resource (fillrate) as far as I know.
On the xbox you have 10MB of ridiculously fast EDRAM , so anything that fits in that 10MB can be done lightning fast.
It's used as framebuffer.
That's why you see these sub HD resolutions or bad shadows or lack of AA on it, because otherwise they simply can't fit the image into the framebuffer anymore, making the edram useless and slowing everything down. (if only the 360 had twice as much EDRAM and some more ram/vram overall)
Anyone else feel free to correct me where/if I'm wrong about any of this
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