Contents

• Dependencies
• Overview
• New Procedures and Functions
• New Tokens
• Errors
• New State
• 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 to clamp a texture without requiring a border, and without using the constant border color.

This extension defines a new texture clamping algorithm. CLAMP_TO_EDGE_SGIS clamps texture coordinates at all mipmap levels such that the texture filter never samples a border texel. When used with a NEAREST or a LINEAR filter, the color returned when clamping is derived only from texels at the edge of the texture image. When used with FILTER4 filters, the filter operations of CLAMP_TO_EDGE_SGIS are defined but don't result in a nice clamp-to-edge color.

CLAMP_TO_EDGE_SGIS is supported by 1, 2, and 3-dimensional textures only.

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_EDGE_SGIS | 0x812F| |:---------------------|:------|

Errors

None

New State

| Get Value | Get Command | Type | Initial Value | |:--------------|:----------------|:---------|:------------------| |TEXTURE_WRAP_S|GetTexParameteriv|n x Z3 |REPEAT | |TEXTURE_WRAP_T|GetTexParameteriv|n x Z3 |REPEAT | |TEXTURE_WRAP_R_EXT|GetTexParameteriv|n x Z3 |REPEAT |

New Implementation Dependent State

None