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Old 05-27-03, 06:00 PM   #25
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Originally posted by Morrow
FP24 minimum for DX9? Please explain the following quote:

"DX9 and ARB_fragment_program assume 32 bit float operation, and ATI just converts everything to 24 bit."

Isn't that exactly what I was saying, namely that ATI is rendering in a lower precision than they are supposed to and "assumed by DX9". So my question if ATI is cheating since they are using the faster FP24 mode and nvidia the slower but higher precision FP32 mode was not that wrong to ask after all
Actually, if I remember correctly the entire R300 pipeline supports FP32 (128-bit), apart from the Pixel Shaders which are FP24 (96-bit).

Considering that NV30 has to lower the quality for everything to FP16 or FX12 to avoid cutting its performance in half, you could spin the whole 'whose cheating now?' argument around again.

At the end of the day, nobody is cheating in the sense of what precision they are using, all that's happened is that both IHVs have chosen different strategies for their architectures, both of which have their good and bad points.
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