gluBuild2DMipmaps — builds a two-dimensional mipmap
GLint gluBuild2DMipmaps( | GLenum target, |
GLint internalFormat, | |
GLsizei width, | |
GLsizei height, | |
GLenum format, | |
GLenum type, | |
const void * data) ; |
target
Specifies the target texture. Must be GLU_TEXTURE_2D
.
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
Specifies in pixels the width and height, respectively, 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.
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 GLU_MAX_TEXTURE_SIZE
.)
Next, a series of mipmap levels is built by decimating a copy of data
in half along both dimensions until size
glTexImage2D is called to load each of these mipmap levels.
Level 0 is a copy of data
. The highest level is
width
is 64 and height
is 16
and the implementation can store a texture of this size, the following
mipmap levels are built:
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.
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
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 and if the GLU version is 1.3 or greater.
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 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
.
gluBuild1DMipmapLevels, gluBuild1DMipmaps, gluBuild2DMipmapLevels, gluBuild3DMipmapLevels, gluBuild3DMipmaps, gluErrorString, glDrawPixels, glGetTexImage, glGetTexLevelParameter, glTexImage1D, glTexImage2D, glTexImage3D
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see https://khronos.org/registry/OpenGL-Refpages/LICENSES/LicenseRef-FreeB.txt.