Contents

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

Dependencies

Written based on the wording of the OpenGL 1.2 specification.

Affects GL_ARB_multitexture.

Overview

OpenGL computes a texture level-of-detail parameter, called lambda in the GL specification, that determines which mipmap levels and their relative mipmap weights for use in mipmapped texture filtering.

This extension provides a means to bias the lambda computation by a constant (signed) value. This bias can provide a way to blur or pseudo-sharpen OpenGL's standard texture filtering.

This blurring or pseudo-sharpening may be useful for special effects (such as depth-of-field effects) or image processing techniques (where the mipmap levels act as pre-downsampled image versions). On some implementations, increasing the texture lod bias may improve texture filtering performance (at the cost of texture bluriness).

The extension mimics functionality found in Direct3D.

New Procedures and Functions

None

New Tokens

Accepted by the

<target>

parameters of GetTexEnvfv, GetTexEnviv, TexEnvi, TexEnvf, TexEnviv, and TexEnvfv:

|TEXTURE_FILTER_CONTROL_EXT | 0x8500| |:---------------------------------|:----------|

When the

<target>

parameter of GetTexEnvfv, GetTexEnviv, TexEnvi, TexEnvf, TexEnviv, and TexEnvfv is TEXTURE_FILTER_CONTROL_EXT, then the value of

<pname>

may be:

|TEXTURE_LOD_BIAS_EXT | 0x8501| |:-------------------------|:------|

Accepted by the

<pname>

parameters of GetBooleanv, GetIntegerv, GetFloatv, and GetDoublev:

|MAX_TEXTURE_LOD_BIAS_EXT | 0x84FD| |:----------------------------|:------|

Errors

INVALID_ENUM is generated when TexEnv is called with a

<pname>

of TEXTURE_FILTER_CONTROL_EXT and the value of

<param>

or what is pointed to by

<params>

is not TEXTURE_LOD_BIAS_EXT.

New State