HI Christopher, thanks for the reply, and sorry I should have been
more specific (about the passing on information).
I'm writing fragment shaders to calculate stuff and store information
(porting a fluid simulation I'd written in C (based on the famous Jos
Stam paper) to GLSL - with the help of some Cg from gpgpu.com), then I
want to feed these into other fragment shaders - so they will be
glorified functions / lookup tables - and show various states of the
fluid (velocity, pressure, curl etc.). When I use
texture2D(sampler2DName, vec2Coordinates), the values come in as
normalized floats, and when I output in my fragment shader
gl_FragColor=vec4(...), again it takes in normalized float values -
but then as soon as its written to the frame buffer internally it gets
converted to an 8bit integer (I'm sure you know this already). So when
I 'render in image' and get that output image, it has been quantized
to 256 levels - that is what I'm trying to avoid. Ideally the 'render
in image' patch would have the option of rendering to a float texture
- but of course it doesn't - but I don't know enough about the
internal workings of QC (or opengl) to know if a custom 'render in
image' can be written which does render to a float texture....
Memo (Mehmet S. Akten)
www.memo.tv
[EMAIL PROTECTED]
On 17 Jun 2008, at 13:55, Christopher Wright wrote:
Hi all, is it possible to setup QC to use float textures? I want to
create a few GLSL shaders that input and output float textures but
couldn't find anywhere to set it up...
In leopard, float textures are supported when the video card
supports them I think. GLSL doesn't output textures, but it'll use
the textures you provide for input. CoreImage filters handle float
textures just fine, as far as I've been able to tell. Ultimately,
it depends on the context that's provided to QC. In the QC app
itself, I don't think the context is floating point, but in external
apps it possibly could be.
also I'd like to use the output of some GLSL shaders as inputs to
other GLSL shaders, so currently i'm doing a render in image for
the shaders and connecting them up, is this the best (if not only)
way to do this?
That depends on what you mean by "output" -- GLSL shaders currently
perform 2 operations: Vertex transformation and fragment
generation. When you feel a render-in-image into a GLSL patch (as a
texture), you're just feeding the fragment part back through. If
that's all you need to accomplish what you're interested in doing,
then that's perfectly fine -- it's currently the only way to do
it. If you need to pass transformed vertices through another
Vertex Shader though, you're out of luck for the time being:
there's no provision for transformation feedback in GLSL in QC yet.
--
[ christopher wright ]
[EMAIL PROTECTED]
http://kineme.net/
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