32 per RGBA bits in framebuffer? Really?

[am2020]

Am I the only one that do not believe this? If this is really true then please tell me so. Apparently I am the only one in the forums worried about this... might be the work I am doing.

The reality if that if GeforceFX gives me the 32 bits they advertised, then I will kiss my Onyx2s goodbye.

[Nv40]

Originally posted by am2020
Am I the only one that do not believe this? If this is really true then please tell me so. Apparently I am the only one in the forums worried about this... might be the work I am doing.

The reality if that if GeforceFX gives me the 32 bits they advertised, then I will kiss my Onyx2s goodbye.


then kiss you SGi onix system ,because its true :)

The GeforceFx stronger side its , its internal color presicion
32bits per color channel x 4 = 128bits across all the Engine.

but for Profesional use ,i think you can wait for the QUADRO
version ,and see if the extra features are important for you .

usually Hardware antialiasing ,Hardware overlay planes,
multimonitors Digital support ,special drivers and a couple of
more nifty things , makes the diference between a gaming card
and a Profesional one .

look at www.nvidia.com for more info ..

[nutball]

Ummm... careful, 32-bits-per-component are not in frame buffers. Frame-buffers as in the buffers which drive the DACs which drive the monitor.

Off-screen buffers support 32-bpc floating-point, but there are limitations on what you can do within these buffers (no blending, for example).

There are other wider integer frame-buffer formats available (can't remember the precise details, 12-bpc I think, but not 16-bpc). I haven't seen anything which might suggest that NV30 is capable of performing on-screen rendering at a colour depth higher than your typical high-end SGI kit (eg. 48-bits-per-pixel on our InfiniteReality3). Which is a shame...

[am2020]

That's exactly my point. I also have an IR3 based Onyx2, and I keep watching NVIDIA and others for they day when I can more than 12 bits depth in each RGBA --- in the framebuffer so I can read it in full bit-glory! --- in a PC platform.

[Bigus Dickus]

In a discussion at Beyond3D, I asked this question about the R300's capabilities in this regard.

Does the framebuffer support 128-bit floating point precision, or an off-screen buffer? If it's the framebuffer, is there a way to transfer 128-bit final rendered frames over the AGP bus before downconversion in the DAC's to a lower integer precision?

The response by OpenGL guy, a driver developer at ATi, was this:
My understanding is that you can create a 128-bit renderable texture. Once you get the data into the texture, I assume you can lock it and read it back, but I don't know what DX9 has to say about that.

So, it sounds like the capability in hardware might be there, but either it is not exposed in the drivers/API, or would require a custom shader program to render the data to a texture for reading. It doesn't sound like this has been acomplished at this time.

The NV30 is probably comparable in capability hardware wise, but perhaps when it launches nVidia will have a utility available to make this possible, since they are promoting this GPU for the developer and off-line rendering market.