In my previous news, I said that FP64 (64-bit double precision floating point) operations will be emulated in software mode on CPU. Actually this is NOT TRUE!
AMD just informed me that there is some partial FP64 support on HD 5770 and HD 5750 and, thanks to some clever routines in the OpenGL driver, FP64 operations will be executed all the same by the Juniper GPU (the GPU behind HD 5770 5750). So only minor performance drops are expected.
This is a rather good news for all Radeon HD 5770/5750 owners!
And thanks to AMD for the clarification!
Anyway, as soon as Catalyst will have OpenGL 4.0 support, I’ll do some FP64 tests with a little R5770 Hawk…
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I wonder if it supports D3D11_FEATURE_DOUBLES under Direct3D 11 too?
That would be the D3D equivalent of GL_ARB_gpu_shader_fp64
It’s obviously not going to run with CPU emulation … this is a sally idea.
However, the partial support would probably be based on some clever emulation using float and some tricks
Here is a link from how they are going to do (bottom):
http://oscarbg.blogspot.com/2009/10/double-precision-support-in-gpu.html
This is a MASSIVE slow down
Interesting articel Groove!
Any idea if GL_ARB_gpu_shader_fp64 will be exposed on DX10 GPUs that have some form of hardware double FP support? (Also what about DX11’s D3D11_FEATURE_DOUBLES for those older cards too?)
I wonder what games will ever use doubles anyway? Surely it is too slow even with Fermi’s 1/2 speed. Seems like doubles are only needed for GPGPU.
Exactly doubles do not make sense in nearly all graphics context unless you want to display a km^2 sized terrain with nm^2 detail level.
Half speed is a fairly good rate. Being limited my processing power on today GPU is hard!
I would not expect a slow down bigger than 25%. But beside GPGPU and some physics it’s a no point.
GL_ARB_gpu_shader_fp64 should be available on any OpenGL 3.X card that support double, including Radeon HD 2XXX, 3XXX, 4XXX, GeForce 8/9/200
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