Re: [Openexr-devel] Shade me confused

[Nafees Bin Zafar]

Wheeeee.  It works!!!

NVRM version: NVIDIA Linux x86 nvidia.o Kernel Module  1.0-4348  Mon Mar 
24 16:36:50 PST 2003

diff -r1.1 ImageViewFragShader.cpp
130c130
<     float *ptr = _floatPixels;
---
>     half *ptr = _floatPixels;
150c150
<           GL_RGBA, GL_FLOAT, _floatPixels);
---
>           GL_RGBA, GL_HALF_FLOAT_NV, _floatPixels);


diff -r1.1 ImageViewFragShader.h
92c92
<     Imf::Array<float>   _floatPixels;
---
>     Imf::Array<half>   _floatPixels;


Thanks Drew!

-n



Drew Hess wrote:

> It's already there.  If you look in glext.h in the Nvidia Cg SDK, you'll 
> find this:
>
> #define GL_HALF_FLOAT_NV                  0x140B
>
> So if you have a half framebuffer, all you really need to do is change the
> input pixel type to GL_HALF_FLOAT_NV in the glTexImage2D call (once the
> bug is fixed) and it should work.
>
> We use half to represent color channels and float for things like Z,
> normals, etc.
>
>
> -dwh-
>
>
>
> On Thu, 27 Mar 2003, Nafees Bin Zafar wrote:
>
>  
>
> > Are there plans for a GL_HALF_NV type?  I would thing it would be at 
> > least equally natural for the main program to do the conversion to half, 
> > and explicitly specify that it's sending in half format data.  Also it 
> > is plausible to imagine that an application's internal format is half, 
> > in which case there would have to be a convert to float, only for a 
> > convert back to half to occur right away in the driver.
> >
> > Or am I missing something?  Is comptime's internal format half, or 
> > float?  Nuke uses floats.
> >
> > -n
> >
> > Drew Hess wrote:
> >
> >    
> >
> > > It is float data that gets uploaded to the card, due to a bug in the 
> > > current (as of 4290) Nvidia drivers.  Once the bug is fixed, we'll be able 
> > > to send half data to the card instead.  It may be fixed in today's 4390 
> > > drivers on Windows, but I'm waiting for the equivalent Linux drivers to 
> > > find out.
> > >
> > > The magic conversion happens in the glTexImage2D call (the GL_FLOAT 
> > > parameter specifies the input pixel type).
> > >
> > >
> > > -dwh-
> > >
> > >
> > > On Thu, 27 Mar 2003, Nafees Bin Zafar wrote:
> > >
> > >
> > >
> > >      
> > >
> > > > Hi Drew.  Looking through the ImageViewFragShader class, I see that the 
> > > > texel data passed into glTexImage2D() is just regular float data.  The 
> > > > internal format spec is set to GL_FLOAT_RGBA16_NV.  So where does the 
> > > > magic conversion to half type occur?
> > > >
> > > > I am hoping that float data doesn't get transferred to the graphics card 
> > > > because that would transfer 16 unnecessary bits.
> > > >
> > > > -n
> > > >
> > > >
> > > >   
> > > >
> > > >        
> > >
> > >
> > >
> > >
> > >      
> >
> >    
>
>
>
>  


--
Nafees Bin Zafar        address@hidden
Zarking Lunatic         310/314-2800 (x2012)
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