1991-2006
Silicon Graphics, Inc.
gluBuild3DMipmaps
3G

# gluBuild3DMipmaps

builds a three-dimensional mipmap

## C Specification

                    GLint gluBuild3DMipmaps
                    GLenum target
                    GLint internalFormat
                    GLsizei width
                    GLsizei height
                    GLsizei depth
                    GLenum format
                    GLenum type
                    const void * data

## Parameters

`target`

  Specifies the target texture. Must be `GLU_TEXTURE_3D`.

`internalFormat`

  Requests the internal storage format of the texture image. The most current version of the SGI implementation of GLU does not check this value for validity before passing it on to the underlying OpenGL implementation. A value that is not accepted by the OpenGL implementation will lead to an OpenGL error. The benefit of not checking this value at the GLU level is that OpenGL extensions can add new internal texture formats without requiring a revision of the GLU implementation. Older implementations of GLU check this value and raise a GLU error if it is not 1, 2, 3, or 4 or one of the following symbolic constants: `GLU_ALPHA`, `GLU_ALPHA4`, `GLU_ALPHA8`, `GLU_ALPHA12`, `GLU_ALPHA16`, `GLU_LUMINANCE`, `GLU_LUMINANCE4`, `GLU_LUMINANCE8`, `GLU_LUMINANCE12`, `GLU_LUMINANCE16`, `GLU_LUMINANCE_ALPHA`, `GLU_LUMINANCE4_ALPHA4`, `GLU_LUMINANCE6_ALPHA2`, `GLU_LUMINANCE8_ALPHA8`, `GLU_LUMINANCE12_ALPHA4`, `GLU_LUMINANCE12_ALPHA12`, `GLU_LUMINANCE16_ALPHA16`, `GLU_INTENSITY`, `GLU_INTENSITY4`, `GLU_INTENSITY8`, `GLU_INTENSITY12`, `GLU_INTENSITY16`, `GLU_RGB`, `GLU_R3_G3_B2`, `GLU_RGB4`, `GLU_RGB5`, `GLU_RGB8`, `GLU_RGB10`, `GLU_RGB12`, `GLU_RGB16`, `GLU_RGBA`, `GLU_RGBA2`, `GLU_RGBA4`, `GLU_RGB5_A1`, `GLU_RGBA8`, `GLU_RGB10_A2`, `GLU_RGBA12`, or `GLU_RGBA16`.

`width`
`height`
`depth`

  Specifies in pixels the width, height and depth respectively, in pixels of the texture image.

`format`

  Specifies the format of the pixel data. Must be one of `GLU_COLOR_INDEX`, `GLU_DEPTH_COMPONENT`, `GLU_RED`, `GLU_GREEN`, `GLU_BLUE`, `GLU_ALPHA`, `GLU_RGB`, `GLU_RGBA`, `GLU_BGR`, `GLU_BGRA`, `GLU_LUMINANCE`, or `GLU_LUMINANCE_ALPHA`.

`type`

  Specifies the data type for `data`. Must be one of: `GLU_UNSIGNED_BYTE`, `GLU_BYTE`, `GLU_BITMAP`, `GLU_UNSIGNED_SHORT`, `GLU_SHORT`, `GLU_UNSIGNED_INT`, `GLU_INT`, `GLU_FLOAT`, `GLU_UNSIGNED_BYTE_3_3_2`, `GLU_UNSIGNED_BYTE_2_3_3_REV`, `GLU_UNSIGNED_SHORT_5_6_5`, `GLU_UNSIGNED_SHORT_5_6_5_REV`, `GLU_UNSIGNED_SHORT_4_4_4_4`, `GLU_UNSIGNED_SHORT_4_4_4_4_REV`, `GLU_UNSIGNED_SHORT_5_5_5_1`, `GLU_UNSIGNED_SHORT_1_5_5_5_REV`, `GLU_UNSIGNED_INT_8_8_8_8`, `GLU_UNSIGNED_INT_8_8_8_8_REV`, `GLU_UNSIGNED_INT_10_10_10_2`, or `GLU_UNSIGNED_INT_2_10_10_10_REV`.

`data`

  Specifies a pointer to the image data in memory.

## Description

`gluBuild3DMipmaps` builds a series of prefiltered three-dimensional texture maps of decreasing resolutions called a mipmap. This is used for the antialiasing of texture-mapped primitives.

A return value of zero indicates success, otherwise a GLU error code is returned (see gluErrorString).

Initially, the `width`, `height` and `depth` of `data` are checked to see if they are a power of 2. If not, a copy of `data` is made and scaled up or down to the nearest power of 2. (If `width`, `height`, or `depth` is exactly between powers of 2, then the copy of `data` will scale upwards.) This copy will be used for subsequent mipmapping operations described below. For example, if `width` is 57, `height` is 23, and `depth` is 24, then a copy of `data` will scale up to 64 in width, down to 16 in height, and up to 32 in depth before mipmapping takes place.

Then, proxy textures (see glTexImage3D) are used to determine if the implementation can fit the requested texture. If not, all three dimensions are continually halved until it fits.

Next, a series of mipmap levels is built by decimating a copy of `data` in half along all three dimensions until size 1 × 1 × 1 is reached. At each level, each texel in the halved mipmap level is an average of the corresponding eight texels in the larger mipmap level. (If exactly one of the dimensions is 1, four texels are averaged. If exactly two of the dimensions are 1, two texels are averaged.)

glTexImage3D is called to load each of these mipmap levels. Level 0 is a copy of `data`. The highest level is log 2 &af; max &af; width height depth . For example, if `width` is 64, `height` is 16, and `depth` is 32, and the implementation can store a texture of this size, the following mipmap levels are built: 64 × 16 × 32 , 32 × 8 × 16 , 16 × 4 × 8 , 8 × 2 × 4 , 4 × 1 × 2 , 2 × 1 × 1 , and 1 × 1 × 1 . These correspond to levels 0 through 6, respectively.

See the glTexImage1D reference page for a description of the acceptable values for `format` parameter. See the glDrawPixels reference page for a description of the acceptable values for `type` parameter.

## Notes

Note that there is no direct way of querying the maximum level. This can be derived indirectly via glGetTexLevelParameter. First, query the width, height, and depth actually used at level 0. (The width, height, and depth may not be equal to `width`, `height`, and `depth` respectively since proxy textures might have scaled them to fit the implementation.) Then the maximum level can be derived from the formula log 2 &af; max &af; width height depth .

`gluBuild3DMipmaps` is only available if the GLU version is 1.3 or greater.

Formats `GLU_BGR`, and `GLU_BGRA`, and types `GLU_UNSIGNED_BYTE_3_3_2`, `GLU_UNSIGNED_BYTE_2_3_3_REV`, `GLU_UNSIGNED_SHORT_5_6_5`, `GLU_UNSIGNED_SHORT_5_6_5_REV`, `GLU_UNSIGNED_SHORT_4_4_4_4`, `GLU_UNSIGNED_SHORT_4_4_4_4_REV`, `GLU_UNSIGNED_SHORT_5_5_5_1`, `GLU_UNSIGNED_SHORT_1_5_5_5_REV`, `GLU_UNSIGNED_INT_8_8_8_8`, `GLU_UNSIGNED_INT_8_8_8_8_REV`, `GLU_UNSIGNED_INT_10_10_10_2`, and `GLU_UNSIGNED_INT_2_10_10_10_REV` are only available if the GL version is 1.2 or greater.

## Errors

`GLU_INVALID_VALUE` is returned if `width`, `height`, or `depth` is < 1.

`GLU_INVALID_ENUM` is returned if `internalFormat`, `format`, or `type` is not legal.

`GLU_INVALID_OPERATION` is returned if `type` is `GLU_UNSIGNED_BYTE_3_3_2` or `GLU_UNSIGNED_BYTE_2_3_3_REV` and `format` is not `GLU_RGB`.

`GLU_INVALID_OPERATION` is returned if `type` is `GLU_UNSIGNED_SHORT_5_6_5` or `GLU_UNSIGNED_SHORT_5_6_5_REV` and `format` is not `GLU_RGB`.

`GLU_INVALID_OPERATION` is returned if `type` is `GLU_UNSIGNED_SHORT_4_4_4_4` or `GLU_UNSIGNED_SHORT_4_4_4_4_REV` and `format` is neither `GLU_RGBA` nor `GLU_BGRA`.

`GLU_INVALID_OPERATION` is returned if `type` is `GLU_UNSIGNED_SHORT_5_5_5_1` or `GLU_UNSIGNED_SHORT_1_5_5_5_REV` and `format` is neither `GLU_RGBA` nor `GLU_BGRA`.

`GLU_INVALID_OPERATION` is returned if `type` is `GLU_UNSIGNED_INT_8_8_8_8` or `GLU_UNSIGNED_INT_8_8_8_8_REV` and `format` is neither `GLU_RGBA` nor `GLU_BGRA`.

`GLU_INVALID_OPERATION` is returned if `type` is `GLU_UNSIGNED_INT_10_10_10_2` or `GLU_UNSIGNED_INT_2_10_10_10_REV` and `format` is neither `GLU_RGBA` nor `GLU_BGRA`.

## See Also

gluBuild1DMipmapLevels, gluBuild1DMipmaps, gluBuild2DMipmapLevels, gluBuild3DMipmapLevels, `gluBuild3DMipmaps`, gluErrorString, glDrawPixels, glGetTexImage, glGetTexLevelParameter, glTexImage1D, glTexImage2D, glTexImage3D

## 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/.