gluBuild2DMipmapLevels(3) gluBuild2DMipmapLevels(3)
NAME
gluBuild2DMipmapLevels - builds a subset of two-dimensional mipmap lev-
els
C SPECIFICATION
GLint gluBuild2DMipmapLevels( GLenum target,
GLint internalFormat,
GLsizei width,
GLsizei height,
GLenum format,
GLenum type,
GLint level,
GLint base,
GLint max,
const void *data )
PARAMETERS
target Specifies the target texture. Must be GL_TEXTURE_2D.
internalFormat Requests the internal storage format of the texture
image. The most current version of the SGI implementa-
tion of GLU does not check this value for validity
before passing it on to the underlying OpenGL implemen-
tation. A value that is not accepted by the OpenGL
implementation will lead to an OpenGL error. The bene-
fit 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: 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 the width and height, respectively, in pixels
of the texture image. These should be a power of 2.
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.
level Specifies the mipmap level of the image data.
base Specifies the minimum mipmap level to pass to glTexIm-
age2D.
max Specifies the maximum mipmap level to pass to glTexIm-
age2D.
data Specifies a pointer to the image data in memory.
DESCRIPTION
gluBuild2DMipmapLevels builds a subset 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).
A series of mipmap levels from base to max is built by decimating data
in half along both dimensions until size 1x1 is reached. At each level,
each texel in the halved mipmap level is an average of the correspond-
ing four texels in the larger mipmap level. (In the case of rectangular
images, the decimation will ultimately reach an Nx1 or 1xN configura-
tion. Here, two texels are averaged instead.) glTexImage2D is called
to load these mipmap levels from base to max. If max is larger than the
highest mipmap level for the texture of the specified size, then a GLU
error code is returned (see gluErrorString) and nothing is loaded.
For example, if level is 2 and width is 16 and height is 8, the follow-
ing levels are possible: 16x8, 8x4, 4x2, 2x1, 1x1. These correspond to
levels 2 through 6 respectively. If base is 3 and max is 5, then only
mipmap levels 8x4, 4x2 and 2x1 are loaded. However, if max is 7 then an
error is returned and nothing is loaded since max is larger than the
highest mipmap level which is, in this case, 6.
The highest mipmap level can be derived from the formula
log2(max(width,height)*(2^level)).
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
gluBuild2DMipmapLevels is only available if the GLU version is 1.3 or
greater.
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.
ERRORS
GLU_INVALID_VALUE is returned if level > base, base < 0, max < base or
max is > the highest mipmap level for data.
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(3), glTexImage1D(3), glTexImage2D(3), glTexImage3D(3),
gluBuild1DMipmaps(3), gluBuild2DMipmaps(3), gluBuild3DMipmaps(3),
gluErrorString(3), glGetTexImage(3), glGetTexLevelParameter(3),
gluBuild1DMipmapLevels(3), gluBuild3DMipmapLevels(3)
gluBuild2DMipmapLevels(3)
Mac OS X 10.6 - Generated Thu Sep 17 20:20:32 CDT 2009