Speculation on performance of doom3 on Macs
I have a PC that is in specs similar to powerbooks/imacs. I bought doom3 a week ago and at first it ran poorly. I then went to do some tweaking and here are the results of the timedemo demo1 benchmark I ran. The first score is of the first run and the 2nd score of the 2nd run. These differ because doom3 caches openGL states. Between each scores. I only note the changes I made to the system/setup.
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PC: AMD athlon 1200mhz, geforce 4200ti 128mb, 256mb SDRAM133, AGP4X, Windows2000Pro, desktop 640x480x32bit, no tray icons, no background
Drivers: nVidia 42.80, DirectX 9.0b
Doom3: low quality, 640x480x32bit, no shadows, 22kHz sounds, preload images, maxImage 256, noCompressedTextures, lodBias 0.7
344.6s = 6.2FPS ][ 177.3s = 12.1FPS
Quite poor performance: barely playable
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nVidia 61.77
151.8s = 14.3FPS ][ 80.8s = 26.6FPS
Great performance gain. The new drivers doubled the performance!
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512mb DDR266
93.3s = 23FPS ][ 77s = 27.9FPS
The better ram shows two effects. The previous 256mb ram was below minimum spec (384mb), while with 512mb we are above it. It clearly shows that in the first run, caching OpenGL-states goes much faster when you have 512mb available. FPS where up to 23FPS from 14.3FPS. In the second run you can see the advantage of DDR266 over SDRAM133. In the second run the states are already cached so the only advantage comes from the speed of the RAM. This is a benefit of a slight 1.3FPS.
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Doom3: 800x600x32bit, reset all settings to medium quality (shadows on, no high quality effects)
111.4s = 19.3FPS ][ 98.8s = 21.7FPS
I consider this the best trade-off between quality and playability
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AA4x
184.2s = 11.7FPS ][ -
No, this is too heavy
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CONCLUSION:
How doom3 will run on Macs primarily depends on how well the videocard drivers are. Since the quality of the drivers on the Mac have always lagged behind PC-drivers this may be a realy important issue. Second thing is that the speed of the memory on G4 machines is not that good, but as long as you have plenty of ram (which most macs have) this is not a real big issue. Keep in mind that the geforce 4200ti is faster than a Radeon 9200 or a geforce FX5200, so iMac and eMac users might have to run in 640x480mode. Powerbook Users (Radeon 9600m & Radeon 9700m) can probably turn high quality effects on (DirectX9/PixelShaders) and run in (1024x768). A problem is however that a lot of macs have 64mb videocards, which means that they are forced to run in low quality mode (resolution can remain at 1024x768 though). This is especially true, because G4-systems have a slow bus speed (133mhz/166mhz) and only have an AGP4X interface so you can't pump large quantities of texture data over the system bus.