Re: [PyOpenGL-Users] Texture colour wrapping

[Dirk R. <dir...@gm...>]

	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