GLUBUILD2DMIPMAPLEVELS(3G) GLUBUILD2DMIPMAPLEVELS(3G)
NAME
gluBuild2DMipmapLevels - builds a subset of two-dimensional mipmap levels
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 implementation of GLU does not check this value for validity before pass-ing passing
ing 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 implementa-tions implementations
tions 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 glTexImage2D.
max Specifies the maximum mipmap level to pass to glTexImage2D.
data Specifies a pointer to the image data in memory.
DESCRIPTION
gluBuild2DMipmapLevels builds a subset of prefiltered two-dimensional texture maps of decreasing res-olutions resolutions
olutions 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
corresponding four texels in the larger mipmap level. (In the case of rectangular images, the decima-tion decimation
tion will ultimately reach an Nx1 or 1xN configuration. Here, two texels are averaged instead.)
glTexImage2D is called to load these mipmap levels from base to max. If max is larger than the high-est highest
est 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 following 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(3G), glTexImage1D(3G), glTexImage2D(3G), glTexImage3D(3G), gluBuild1DMipmaps(3G), gluBuild2DMipmaps(3G),
gluBuild3DMipmaps(3G), gluErrorString(3G), glGetTexImage(3G), glGetTexLevelParameter(3G), gluBuild1DMipmapLevels(3G),
gluBuild3DMipmapLevels(3G)
GLUBUILD2DMIPMAPLEVELS(3G)
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