HL2 forcing FP24 when only FP16 is needed?

[Helevitia]

Apologies if this has been posted.

I wanted to bring this thread to B3D since this is the only place I can trust to get the right answer.

A thread over at [H] claims that Valve forces FP24 in HL2 even though only FP16 is needed. They also claim that this was intentional so that Nvidia is forced to use FP32 which gives them a performance hit in the game.

Now, I don't know the technical aspects of video cards which is why I brought this over to B3D. Can someone clarify that FP16 doesn't cause any visual quality loss of FP24? Also, does anyone have an Nvidia card to test this out?

Thanks,
Dave

 

[CJ]

Apologies accepted

http://www.beyond3d.com/forum/viewtopic.php?t=18604

 

[digitalwanderer]

Yes, no; yes.

 

[rwolf]

Since when is FP16 a Directx9 specification.

I thought the 6800 had good performance with FP32.

 

[Dave Baumann]

FP16 has always been a part of the released DX9 specs, as partial precision. The default precision is full precision which has hardware requirements of at least FP24 under PS2.0 ops.

 

[Moloch]

Since when is FP16 a Directx9 specification.

I thought the 6800 had good performance with FP32.

The argument for the FX series is that DX9 spec says you can use FP16 when possible..