gluBuild2DMipmaps
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## Name

gluBuild2DMipmaps, gluBuild2DMipmapsb, gluBuild2DMipmapsf, gluBuild2DMipmapsi, gluBuild2DMipmapss, gluBuild2DMipmapsub, gluBuild2DMipmapsui, gluBuild2DMipmapsus — builds a two-dimensional mipmap

## C Specification

`GLint `gluBuild2DMipmaps`` | `(` | `GLenum `target`, GLint `internalFormat`, GLsizei `width`, GLsizei `height`, GLenum `format`, GLenum `type`, const void *`data`);`

## Python Specification

``gluBuild2DMipmaps`` | `(` | ``target`, `internalFormat`, `width`, `height`, `format`, `type`, `data`) → `None``
``gluBuild2DMipmapsb`` | `(` | ``target`, `internalFormat`, `format`, `data`) → `None``
``gluBuild2DMipmapsf`` | `(` | ``target`, `internalFormat`, `format`, `data`) → `None``
``gluBuild2DMipmapsi`` | `(` | ``target`, `internalFormat`, `format`, `data`) → `None``
``gluBuild2DMipmapss`` | `(` | ``target`, `internalFormat`, `format`, `data`) → `None``
``gluBuild2DMipmapsub`` | `(` | ``target`, `internalFormat`, `format`, `data`) → `None``
``gluBuild2DMipmapsui`` | `(` | ``target`, `internalFormat`, `format`, `data`) → `None``
``gluBuild2DMipmapsus`` | `(` | ``target`, `internalFormat`, `format`, `data`) → `None``

## Parameters

`target`
  Specifies the target texture. Must be `GL_TEXTURE_2D`.
`internalFormat`
  Requests the internal storage format of the texture image. Must be 1, 2, 3, 4, or one of the following symbolic constants: `GL_ALPHA`, `GL_ALPHA4`, `GL_ALPHA8`, `GL_ALPHA12`, `GL_ALPHA16`, `GL_LUMINANCE`, `GL_LUMINANCE4`, `GL_LUMINANCE8`, `GL_LUMINANCE12`, `GL_LUMINANCE16`, `GL_LUMINANCE_ALPHA`, `GL_LUMINANCE4_ALPHA4`, `GL_LUMINANCE6_ALPHA2`, `GL_LUMINANCE8_ALPHA8`, `GL_LUMINANCE12_ALPHA4`, `GL_LUMINANCE12_ALPHA12`, `GL_LUMINANCE16_ALPHA16`, `GL_INTENSITY`, `GL_INTENSITY4`, `GL_INTENSITY8`, `GL_INTENSITY12`, `GL_INTENSITY16`, `GL_RGB`, `GL_R3_G3_B2`, `GL_RGB4`, `GL_RGB5`, `GL_RGB8`, `GL_RGB10`, `GL_RGB12`, `GL_RGB16`, `GL_RGBA`, `GL_RGBA2`, `GL_RGBA4`, `GL_RGB5_A1`, `GL_RGBA8`, `GL_RGB10_A2`, `GL_RGBA12` or `GL_RGBA16`.
`width`, `height`
  Specifies in pixels the width and height, respectively, of the texture image.
`format`
  Specifies the format of the pixel data. Must be one of `GL_COLOR_INDEX`, `GL_DEPTH_COMPONENT`, `GL_RED`, `GL_GREEN`, `GL_BLUE`, `GL_ALPHA`, `GL_RGB`, `GL_RGBA`, `GL_BGR`, `GL_BGRA`, `GL_LUMINANCE`, or `GL_LUMINANCE_ALPHA`.
`type`
  Specifies the data type for `data`. Must be one of `GL_UNSIGNED_BYTE`, `GL_BYTE`, `GL_BITMAP`, `GL_UNSIGNED_SHORT`, `GL_SHORT`, `GL_UNSIGNED_INT`, `GL_INT`, `GL_FLOAT`, `GL_UNSIGNED_BYTE_3_3_2`, `GL_UNSIGNED_BYTE_2_3_3_REV`, `GL_UNSIGNED_SHORT_5_6_5`, `GL_UNSIGNED_SHORT_5_6_5_REV`, `GL_UNSIGNED_SHORT_4_4_4_4`, `GL_UNSIGNED_SHORT_4_4_4_4_REV`, `GL_UNSIGNED_SHORT_5_5_5_1`, `GL_UNSIGNED_SHORT_1_5_5_5_REV`, `GL_UNSIGNED_INT_8_8_8_8`, `GL_UNSIGNED_INT_8_8_8_8_REV`, `GL_UNSIGNED_INT_10_10_10_2`, or `GL_UNSIGNED_INT_2_10_10_10_REV`.
`data`
  Specifies a pointer to the image data in memory.

## Description

`gluBuild2DMipmaps` builds a series of prefiltered two-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` and `height` of `data` are checked to see if they are a power of 2. If not, a copy of `data` (not `data`), is scaled up or down to the nearest power of 2. This copy will be used for subsequent mipmapping operations described below. (If `width` or `height` is exactly between powers of 2, then the copy of `data` will scale upwards.) For example, if `width` is 57 and `height` is 23 then a copy of `data` will scale up to 64 in `width` and down to 16 in depth, before mipmapping takes place.

Then, proxy textures (see glTexImage2D) are used to determine if the implementation can fit the requested texture. If not, both dimensions are continually halved until it fits. (If the OpenGL version is ≤ 1.0, both maximum texture dimensions are clamped to the value returned by `glGetIntegerv` with the argument `GL_MAX_TEXTURE_SIZE`.)

Next, a series of mipmap levels is built by decimating a copy of `data` in half along both dimensions until size 1 × 1 is reached. At each level, each texel in the halved mipmap level is an average of the corresponding four texels in the larger mipmap level. (In the case of rectangular images, the decimation will ultimately reach an N × 1 or 1 × N configuration. Here, two texels are averaged instead.)

`glTexImage2D` is called to load each of these mipmap levels. Level 0 is a copy of `data`. The highest level is log 2 ( max ( width height ) ) . For example, if `width` is 64 and `height` is 16 and the implementation can store a texture of this size, the following mipmap levels are built: 64 × 16 , 32 × 8 , 16 × 4 , 8 × 2 , 4 × 1 , 2 × 1 and 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 for the width and height actually used at level 0. (The width and height may not be equal to `width` and `height` respectively since proxy textures might have scaled them to fit the implementation.) Then the maximum level can be derived from the formula log 2 ( max ( \f 2width \f P \f 2height \f P ) ) .

## Notes

Formats `GL_BGR`, and `GL_BGRA`, and types `GL_UNSIGNED_BYTE_3_3_2`, `GL_UNSIGNED_BYTE_2_3_3_REV`, `GL_UNSIGNED_SHORT_5_6_5`, `GL_UNSIGNED_SHORT_5_6_5_REV`, `GL_UNSIGNED_SHORT_4_4_4_4`, `GL_UNSIGNED_SHORT_4_4_4_4_REV`, `GL_UNSIGNED_SHORT_5_5_5_1`, `GL_UNSIGNED_SHORT_1_5_5_5_REV`, `GL_UNSIGNED_INT_8_8_8_8`, `GL_UNSIGNED_INT_8_8_8_8_REV`, `GL_UNSIGNED_INT_10_10_10_2`, and `GL_UNSIGNED_INT_2_10_10_10_REV` are only available if the GL version is 1.2 or greater and if the GLU version is 1.3 or greater.

## Notes

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

## Notes

Formats `GL_BGR`, and `GL_BGRA`, and types `GL_UNSIGNED_BYTE_3_3_2`, `GL_UNSIGNED_BYTE_2_3_3_REV`, `GL_UNSIGNED_SHORT_5_6_5`, `GL_UNSIGNED_SHORT_5_6_5_REV`, `GL_UNSIGNED_SHORT_4_4_4_4`, `GL_UNSIGNED_SHORT_4_4_4_4_REV`, `GL_UNSIGNED_SHORT_5_5_5_1`, `GL_UNSIGNED_SHORT_1_5_5_5_REV`, `GL_UNSIGNED_INT_8_8_8_8`, `GL_UNSIGNED_INT_8_8_8_8_REV`, `GL_UNSIGNED_INT_10_10_10_2`, and `GL_UNSIGNED_INT_2_10_10_10_REV` are only available if the GL version is 1.2 or greater and if the GLU version is 1.3 or greater.

## Errors

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

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

`GLU_INVALID_OPERATION` is returned if `type` is `GL_UNSIGNED_BYTE_3_3_2` or `GL_UNSIGNED_BYTE_2_3_3_REV` and `format` is not `GL_RGB`.

`GLU_INVALID_OPERATION` is returned if `type` is `GL_UNSIGNED_SHORT_5_6_5` or `GL_UNSIGNED_SHORT_5_6_5_REV` and `format` is not `GL_RGB`.

`GLU_INVALID_OPERATION` is returned if `type` is `GL_UNSIGNED_SHORT_4_4_4_4` or `GL_UNSIGNED_SHORT_4_4_4_4_REV` and `format` is neither `GL_RGBA` nor `GL_BGRA`.

`GLU_INVALID_OPERATION` is returned if `type` is `GL_UNSIGNED_SHORT_5_5_5_1` or `GL_UNSIGNED_SHORT_1_5_5_5_REV` and `format` is neither `GL_RGBA` nor `GL_BGRA`.

`GLU_INVALID_OPERATION` is returned if `type` is `GL_UNSIGNED_INT_8_8_8_8` or `GL_UNSIGNED_INT_8_8_8_8_REV` and `format` is neither `GL_RGBA` nor `GL_BGRA`.

`GLU_INVALID_OPERATION` is returned if `type` is `GL_UNSIGNED_INT_10_10_10_2` or `GL_UNSIGNED_INT_2_10_10_10_REV` and `format` is neither `GL_RGBA` nor `GL_BGRA`.

## See Also

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

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