OpenGL extension SGIS.texture_border_clamp
This module customises the behaviour of the OpenGL.raw.GL.SGIS.texture_border_clamp to provide a more Python-friendly API
Overview (from the spec)
The base OpenGL provides clamping such that the texture coordinates are limited to exactly the range [0,1]. When a texture coordinate is clamped using this algorithm, the texture sampling filter straddles the edge of the texture image, taking 1/2 its sample values from within the texture image, and the other 1/2 from the texture border. It is sometimes desirable for a texture to be clamped to the border color, rather than to an average of the border and edge colors.
This extension defines an additional texture clamping algorithm. CLAMP_TO_BORDER_SGIS clamps texture coordinates at all mipmap levels such that NEAREST and LINEAR filters return the color of the border texels. When used with FILTER4 filters, the filter operation of CLAMP_TO_BORDER_SGIS is defined but doesn't result in a nice clamp-to-border color.
The official definition of this extension is available here: