Contents

• Dependencies
• Overview
• New Procedures and Functions
• New Tokens
• Errors
• New Implementation Dependent State

Dependencies

GL_EXT_texture3D affects the definition of this extension

GL_SGIS_texture_filter4 affects the definition of this extension

Overview

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.

New Procedures and Functions

None

New Tokens

Accepted by the

<param>

parameter of TexParameteri and TexParameterf, and by the

<params>

parameter of TexParameteriv and TexParameterfv, when their

<pname>

parameter is TEXTURE_WRAP_S, TEXTURE_WRAP_T, or TEXTURE_WRAP_R_EXT:

|CLAMP_TO_BORDER_SGIS | 0x812D| |:-----------------------|:------|

Errors

None

New Implementation Dependent State

None