1991-2006
Silicon Graphics, Inc.
glGetTexLevelParameter
3G

# glGetTexLevelParameter

return texture parameter values for a specific level of detail

## C Specification

                    void glGetTexLevelParameterfv
                    GLenum target
                    GLint level
                    GLenum pname
                    GLfloat * params

                    void glGetTexLevelParameteriv
                    GLenum target
                    GLint level
                    GLenum pname
                    GLint * params

## Parameters

`target`

  Specifies the symbolic name of the target texture, either `GL_TEXTURE_1D`, `GL_TEXTURE_2D`, `GL_TEXTURE_3D`, `GL_PROXY_TEXTURE_1D`, `GL_PROXY_TEXTURE_2D`, `GL_PROXY_TEXTURE_3D`, `GL_TEXTURE_CUBE_MAP_POSITIVE_X`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_X`, `GL_TEXTURE_CUBE_MAP_POSITIVE_Y`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_Y`, `GL_TEXTURE_CUBE_MAP_POSITIVE_Z`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_Z`, or `GL_PROXY_TEXTURE_CUBE_MAP`.

`level`

  Specifies the level-of-detail number of the desired image. Level 0 is the base image level. Level n is the nth mipmap reduction image.

`pname`

  Specifies the symbolic name of a texture parameter. `GL_TEXTURE_WIDTH`, `GL_TEXTURE_HEIGHT`, `GL_TEXTURE_DEPTH`, `GL_TEXTURE_INTERNAL_FORMAT`, `GL_TEXTURE_BORDER`, `GL_TEXTURE_RED_SIZE`, `GL_TEXTURE_GREEN_SIZE`, `GL_TEXTURE_BLUE_SIZE`, `GL_TEXTURE_ALPHA_SIZE`, `GL_TEXTURE_LUMINANCE_SIZE`, `GL_TEXTURE_INTENSITY_SIZE`, `GL_TEXTURE_DEPTH_SIZE`, `GL_TEXTURE_COMPRESSED`, and `GL_TEXTURE_COMPRESSED_IMAGE_SIZE` are accepted.

`params`

  Returns the requested data.

## Description

`glGetTexLevelParameter` returns in `params` texture parameter values for a specific level-of-detail value, specified as `level`. `target` defines the target texture, either `GL_TEXTURE_1D`, `GL_TEXTURE_2D`, `GL_TEXTURE_3D`, `GL_PROXY_TEXTURE_1D`, `GL_PROXY_TEXTURE_2D`, `GL_PROXY_TEXTURE_3D`, `GL_TEXTURE_CUBE_MAP_POSITIVE_X`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_X`, `GL_TEXTURE_CUBE_MAP_POSITIVE_Y`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_Y`, `GL_TEXTURE_CUBE_MAP_POSITIVE_Z`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_Z`, or `GL_PROXY_TEXTURE_CUBE_MAP`.

`GL_MAX_TEXTURE_SIZE`, and `GL_MAX_3D_TEXTURE_SIZE` are not really descriptive enough. It has to report the largest square texture image that can be accommodated with mipmaps and borders, but a long skinny texture, or a texture without mipmaps and borders, may easily fit in texture memory. The proxy targets allow the user to more accurately query whether the GL can accommodate a texture of a given configuration. If the texture cannot be accommodated, the texture state variables, which may be queried with `glGetTexLevelParameter`, are set to 0. If the texture can be accommodated, the texture state values will be set as they would be set for a non-proxy target.

`pname` specifies the texture parameter whose value or values will be returned.

The accepted parameter names are as follows:

`GL_TEXTURE_WIDTH`

  `params` returns a single value, the width of the texture image. This value includes the border of the texture image. The initial value is 0.

`GL_TEXTURE_HEIGHT`

  `params` returns a single value, the height of the texture image. This value includes the border of the texture image. The initial value is 0.

`GL_TEXTURE_DEPTH`

  `params` returns a single value, the depth of the texture image. This value includes the border of the texture image. The initial value is 0.

`GL_TEXTURE_INTERNAL_FORMAT`

  `params` returns a single value, the internal format of the texture image.

`GL_TEXTURE_BORDER`

  `params` returns a single value, the width in pixels of the border of the texture image. The initial value is 0.

`GL_TEXTURE_RED_SIZE`,
`GL_TEXTURE_GREEN_SIZE`,
`GL_TEXTURE_BLUE_SIZE`,
`GL_TEXTURE_ALPHA_SIZE`,
`GL_TEXTURE_LUMINANCE_SIZE`,
`GL_TEXTURE_INTENSITY_SIZE`,
`GL_TEXTURE_DEPTH_SIZE`

  The internal storage resolution of an individual component. The resolution chosen by the GL will be a close match for the resolution requested by the user with the component argument of glTexImage1D, glTexImage2D, glTexImage3D, glCopyTexImage1D, and glCopyTexImage2D. The initial value is 0.

`GL_TEXTURE_COMPRESSED`

  `params` returns a single boolean value indicating if the texture image is stored in a compressed internal format. The initiali value is `GL_FALSE`.

`GL_TEXTURE_COMPRESSED_IMAGE_SIZE`

  `params` returns a single integer value, the number of unsigned bytes of the compressed texture image that would be returned from glGetCompressedTexImage.

## Notes

If an error is generated, no change is made to the contents of `params`.

`GL_TEXTURE_INTERNAL_FORMAT` is available only if the GL version is 1.1 or greater. In version 1.0, use `GL_TEXTURE_COMPONENTS` instead.

`GL_PROXY_TEXTURE_1D` and `GL_PROXY_TEXTURE_2D` are available only if the GL version is 1.1 or greater.

`GL_TEXTURE_3D`, `GL_PROXY_TEXTURE_3D`, and `GL_TEXTURE_DEPTH` are available only if the GL version is 1.2 or greater.

`GL_TEXTURE_COMPRESSED`, `GL_TEXTURE_COMPRESSED_IMAGE_SIZE`, `GL_TEXTURE_CUBE_MAP_POSITIVE_X`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_X`, `GL_TEXTURE_CUBE_MAP_POSITIVE_Y`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_Y`, `GL_TEXTURE_CUBE_MAP_POSITIVE_Z`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_Z`, and `GL_PROXY_TEXTURE_CUBE_MAP` are available only if the GL version is 1.3 or greater.

For OpenGL versions 1.3 and greater, or when the `ARB_multitexture` extension is supported, `glGetTexLevelParameter` returns the texture level parameters for the active texture unit.

## Errors

`GL_INVALID_ENUM` is generated if `target` or `pname` is not an accepted value.

`GL_INVALID_VALUE` is generated if `level` is less than 0.

`GL_INVALID_VALUE` may be generated if `level` is greater than log 2 max, where max is the returned value of `GL_MAX_TEXTURE_SIZE`.

`GL_INVALID_OPERATION` is generated if `glGetTexLevelParameter` is executed between the execution of glBegin and the corresponding execution of glEnd.

`GL_INVALID_OPERATION` is generated if `GL_TEXTURE_COMPRESSED_IMAGE_SIZE` is queried on texture images with an uncompressed internal format or on proxy targets.

## See Also

glActiveTexture, glGetTexParameter, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, glCopyTexSubImage3D, glTexEnv, glTexGen, glTexImage1D, glTexImage2D, glTexImage3D, glTexSubImage1D, glTexSubImage2D, glTexSubImage3D, glTexParameter

## Copyright

Copyright 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.