[vtkusers] [vtk-developers] Passing arbitrary float data to a shader through a vtkTexture

Ken Martin ken.martin at kitware.com
Tue Feb 19 08:30:18 EST 2019

Two different things here I think

I believe float data in the texture is the full range as long as the
underlying VTK data type is float.

The image buffer (pixels that get drawn to) by default is unsigned char
normalized 0 to 1. To use float you need a float backed image buffer.
Something like


But even with that example in the end the framebuffer will be blitted to
screen which is typically an 8bit buffer. But at least in that example you
can accumulate etc in floating point all you want prior to that final blit
to the screen.

On Mon, Feb 18, 2019 at 7:07 PM Patrick Bergeron <pbergeron at spiria.com>

> Hi.
> I am trying to pass custom float data to my shader in the form of a
> vtkTexture which contains VTK_FLOAT data (4 components).
> As per the documentation, it appears that float data in the
> image buffer gets clamped in the 0-1 range, which is a huge problem for me
> as I'm only getting 0-1 data in the shader: I need the pixel data to be the
> actual float data (which can be anything, not restricted to any particular
> range).
> How can I do this in VTK ?
> Patrick.
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Ken Martin PhD
Distinguished Engineer
Kitware Inc.
101 East Weaver Street
Carrboro, North Carolina
27510 USA

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