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 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 implementa-
tion. 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 follow-
ing 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 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 corresponding four texels in the larger mipmap level. (In the case of
rectangular images, the decimation 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 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 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, glTexImage1D, glTexImage2D, glTexImage3D, gluBuild1DMipmaps, gluBuild2DMipmaps, gluBuild3DMipmaps, gluErrorString, glGetTex-
Image, glGetTexLevelParameter, gluBuild1DMipmapLevels, gluBuild3DMipmapLevels
GLUBUILD2DMIPMAPLEVELS(3G)