Contents

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

Dependencies

None

Overview

The original intention of this extension was simply to support various numeric resolutions of color components in texture images. While it accomplishes this, it also accomplishes a larger task, that of formalizing the notion of an internal format for images, corresponding to the external format that already existed for image data in host memory. This notion of an internal image format will be used extensively in later extensions, especially those concerned with pixel manipulation.

The idea of an internal format is simple: rather than treating a retained image as having 1, 2, 3, or 4 components, treat it as though it has a specific format, such as LUMINANCE_ALPHA, or just ALPHA. Then define the semantics of the use of internal images with these formats in a consistent way. Because texture mapping is already defined in GL, the semantics for internal-format images were chosen to match those of the 1, 2, 3, and 4 component internal images that already existed. The new semantics are a superset of the old ones, however, so this extension adds capabilities to GL, as well as allowing internal resolutions to be specified.

This extension also defines a robust method for applications to determine what combinations of texture dimensions and resolutions are supported by an implementation. It also introduces a new texture environment: REPLACE_EXT.

New Procedures and Functions

None

New Tokens

Accepted by the

<components>

parameter of TexImage1D and TexImage2D:

|ALPHA4_EXT |0x803B| |:---------------------------------|:-----| |ALPHA8_EXT |0x803C| |ALPHA12_EXT |0x803D| |ALPHA16_EXT |0x803E| |LUMINANCE4_EXT |0x803F| |LUMINANCE8_EXT |0x8040| |LUMINANCE12_EXT |0x8041| |LUMINANCE16_EXT |0x8042| |LUMINANCE4_ALPHA4_EXT |0x8043| |LUMINANCE6_ALPHA2_EXT |0x8044| |LUMINANCE8_ALPHA8_EXT |0x8045| |LUMINANCE12_ALPHA4_EXT |0x8046| |LUMINANCE12_ALPHA12_EXT |0x8047| |LUMINANCE16_ALPHA16_EXT |0x8048| |INTENSITY_EXT |0x8049| |INTENSITY4_EXT |0x804A| |INTENSITY8_EXT |0x804B| |INTENSITY12_EXT |0x804C| |INTENSITY16_EXT |0x804D| |RGB2_EXT |0x804E| |RGB4_EXT |0x804F| |RGB5_EXT |0x8050| |RGB8_EXT |0x8051| |RGB10_EXT |0x8052| |RGB12_EXT |0x8053| |RGB16_EXT |0x8054| |RGBA2_EXT |0x8055| |RGBA4_EXT |0x8056| |RGB5_A1_EXT |0x8057| |RGBA8_EXT |0x8058| |RGB10_A2_EXT |0x8059| |RGBA12_EXT |0x805A| |RGBA16_EXT |0x805B|

Accepted by the

<pname>

parameters of GetTexLevelParameteriv and GetTexLevelParameterfv:

|TEXTURE_RED_SIZE_EXT |0x805C| |:-----------------------------------|:-----| |TEXTURE_GREEN_SIZE_EXT |0x805D| |TEXTURE_BLUE_SIZE_EXT |0x805E| |TEXTURE_ALPHA_SIZE_EXT |0x805F| |TEXTURE_LUMINANCE_SIZE_EXT |0x8060| |TEXTURE_INTENSITY_SIZE_EXT |0x8061|

Accepted by the

<params>

parameter of TexEnvf, TexEnvi, TexEnvfv, and TexEnvfi when the

<pname>

parameter value is GL_TEXTURE_ENV_MODE

|REPLACE_EXT |0x8062| |:---------------------------------|:-----|

Accepted by the

<target>

parameters of TexImage1D, GetTexLevelParameteriv, and GetTexLevelParameterfv:

|PROXY_TEXTURE_1D_EXT |0x8063| |:-----------------------------------|:-----|

Accepted by the

<target>

parameters of TexImage2D, GetTexLevelParameteriv, and GetTexLevelParameterfv:

|PROXY_TEXTURE_2D_EXT |0x8064| |:-----------------------------------|:-----|

Errors

The GL Specification requires that INVALID_VALUE be generated if any texture dimension is specified less than zero, greater than MAX_TEXTURE_SIZE, or with a value that cannot be represented as 2k + 2*border, for some integer k. This extension eliminates the requirement that all dimensions be specified less than or equal to MAX_TEXTURE_SIZE, and replaces it with a new error token and error condition. INVALID_VALUE is generated if any texture dimension is specified less than zero, or with a value that cannot be represented as 2k + 2*border. TEXTURE_TOO_LARGE_EXT is generated if the texture is too large to be accommodated, for whatever reason. An implementation must specify MAX_TEXTURE_SIZE such that TEXTURE_TOO_LARGE_EXT is never generated if all the dimensions of the texture are less than or equal to MAX_TEXTURE_SIZE. Also, TEXTURE_TOO_LARGE_EXT is never generated when the target is a proxy texture, such as PROXY_TEXTURE_1D_EXT or PROXY_TEXTURE_2D_EXT.

This change to the error semantics does not require that the major revision level be incremented, because the GL Specification allows for changes to error semantics (Section 2.5).

New State

| Get Value | Get Command | Type | Initial Value | |:--------------|:----------------|:---------|:------------------| |TEXTURE_RED_SIZE_EXT |GetTexLevelParameteriv|2 x 2 x levels x Z+|0 | |TEXTURE_GREEN_SIZE_EXT|GetTexLevelParameteriv|2 x 2 x levels x Z+|0 | |TEXTURE_BLUE_SIZE_EXT|GetTexLevelParameteriv|2 x 2 x levels x Z+|0 | |TEXTURE_ALPHA_SIZE_EXT|GetTexLevelParameteriv|2 x 2 x levels x Z+|0 | |TEXTURE_LUMINANCE_SIZE_EXT|GetTexLevelParameteriv|2 x 2 x levels x Z+|0 | |TEXTURE_INTENSITY_SIZE_EXT|GetTexLevelParameteriv|2 x 2 x levels x Z+|0 | |TEXTURE |GetTexImage |2 x 1 x levels x I|null | |TEXTURE_WIDTH |GetTexLevelParameteriv|2 x 2 x levels x Z+|0 | |TEXTURE_HEIGHT|GetTexLevelParameteriv|1 x 2 x levels x Z+|0 | |TEXTURE_BORDER|GetTexLevelParameteriv|2 x 2 x levels x Z+|0 | |TEXTURE_COMPONENTS|GetTexLevelParameteriv|2 x 2 x levels x Z42|1 |

New Implementation Dependent State

None