Re: [PyOpenGL-Users] Texture colour wrapping

[Brice T. <bps...@gm...>]

Hi Dirk,

Thanks for your help. So if I understand properly, I first do the
geometrical mapping to do the polar to cartesian transformation. Then I do
the color mapping?

That's sound pretty neat to me.

Thanks
Brice

On 5 November 2011 19:02, Dirk Reiners <dir...@gm...> wrote:

>
>        Hi Brice,
>
> On 11/05/2011 01:46 PM, Brice Thurin wrote:
> > Thanks for both your reply. The range of the input data vary but I could
> fix it
> > if it makes things easier.
> >
> > Note I do not want 2pi and 4pi to both map to the same physical
> location, I want
> > 2pi and 4pi to be displayed with the same gray level or colour.
>
> Ah, ok, I was starting to get confused. You really do want the basic input
> value
> -> color mapping.
>
> That's pretty easy. Define the color map that you want to use as a texture
> (1D
> is fine, 2D works too). Set the texture wrapping mode to REPEAT
> (glTexParameter(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_REPEAT)). This makes
> OpenGL
> accept any texture coordinate value and just use the fractional part to
> index
> into the texture.  Use your input values (your -15pi to 15pi) as the
> texture
> coordinate for each vertex. The texture coordinates will always be between
> 0 and
> 1, so if you want the texture to repeat after 2pi you will either need to
> divide
> them by 2pi before giving them to OpenGL, or use a texture matrix to
> divide.
>
> Hope it helps
>
>        Dirk
>
>
>
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