gluBuild1DMipmaps(3G) OpenGL Reference gluBuild1DMipmaps(3G)
NAME
gluBuild1DMipmaps - builds a 1-D mipmap
C SPECIFICATION
GLint gluBuild1DMipmaps( GLenum target,
GLint internalFormat,
GLsizei width,
GLenum format,
GLenum type,
const void *data )
PARAMETERS
target Specifies the target texture. Must be GLTEXTURE1D.
internalFormat Requests the internal storage format of the texture
image. Must be 1, 2, 3, or 4 or one of the following
symbolic constants: GLALPHA, GLALPHA4, GLALPHA8,
GLALPHA12, GLALPHA16, GLLUMINANCE, GLLUMINANCE4,
GLLUMINANCE8, GLLUMINANCE12, GLLUMINANCE16,
GLLUMINANCEALPHA, GLLUMINANCE4ALPHA4,
GLLUMINANCE6ALPHA2, GLLUMINANCE8ALPHA8,
GLLUMINANCE12ALPHA4, GLLUMINANCE12ALPHA12,
GLLUMINANCE16ALPHA16, GLINTENSITY, GLINTENSITY4,
GLINTENSITY8, GLINTENSITY12, GLINTENSITY16, GLRGB,
GLR3G3B2, GLRGB4, GLRGB5, GLRGB8, GLRGB10,
GLRGB12, GLRGB16, GLRGBA, GLRGBA2, GLRGBA4,
GLRGB5A1, GLRGBA8, GLRGB10A2, GLRGBA12 or
GLRGBA16.
width Specifies the width, in pixels, of the texture image.
format Specifies the format of the pixel data. Must be one of:
GLCOLORINDEX, GLDEPTHCOMPONENT, GLRED, GLGREEN,
GLBLUE, GLALPHA, GLRGB, GLRGBA, GLLUMINANCE,
GLLUMINANCEALPHA and GLABGREXT.
type Specifies the data type for data. Must be one of:
GLUNSIGNEDBYTE, GLBYTE, GLBITMAP, GLUNSIGNEDSHORT,
GLSHORT, GLUNSIGNEDINT, GLINT, GLFLOAT,
GLUNSIGNEDBYTE332EXT,
GLUNSIGNEDSHORT4444EXT,
GLUNSIGNEDSHORT5551EXT,
GLUNSIGNEDINT8888EXT, and
GLUNSIGNEDINT1010102EXT.
data Specifies a pointer to the image data in memory.
Page 1
gluBuild1DMipmaps(3G) OpenGL Reference gluBuild1DMipmaps(3G)
DESCRIPTION
gluBuild1DMipmaps builds a series of prefiltered 1-D texture maps of
decreasing resolutions called a mipmap. This is used for the antialiasing
of texture mapped primitives.
A return value of 0 indicates success, otherwise a GLU error code is
returned (see gluErrorString).
Initially, the width of data is checked to see if it is a power of two.
If not, a copy of data is scaled up or down to the nearest power of two.
This copy will be used for subsequent mipmapping operations described
below. (If width is exactly between powers of 2, then the copy of data
will scale upwards.) For example, if width is 57 then a copy of data
will scale up to 64 before mipmapping takes place.
Then, proxy textures (see glTexImage1D) are used to determine if the
implementation can fit the requested texture. If not, width is
continually halved until it fits.
Next, a series of mipmap levels is built by decimating a copy of data in
half until size 1 is reached. At each level, each texel in the halved
mipmap level is an average of the corresponding two texels in the larger
mipmap level.
glTexImage1D is called to load each of these mipmap levels. Level 0 is a
copy of data. The highest level is log2(width). For example, if width is
64 and the implementation can store a texture of this size, the following
mipmap levels are built: 64x1, 32x1, 16x1, 8x1, 4x1, 2x1 and 1x1. These
correspond to levels 0 through 6, respectively.
See the glTexImage1D reference page for a description of the acceptable
values for the type parameter. See the glDrawPixels reference page for a
description of the acceptable values for the data 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 actually used at level 0. (The width may not be equal to width
since proxy textures might have scaled it to fit the implementation.)
Then the maximum level can be derived from the formula log2(width).
ERRORS
GLUINVALIDVALUE is returned if width is < 1.
GLUINVALIDENUM is returned if format or type are not legal.
GLUINVALIDOPERATION is returned if type is GLUNSIGNEDBYTE332EXT
and format is not GLRGB.
GLUINVALIDOPERATION is returned if type is
GLUNSIGNEDSHORT4444EXT and format is neither GLRGBA nor
GLABGREXT.
Page 2
gluBuild1DMipmaps(3G) OpenGL Reference gluBuild1DMipmaps(3G)
GLUINVALIDOPERATION is returned if type is
GLUNSIGNEDSHORT5551EXT and format is neither GLRGBA nor
GLABGREXT.
GLUINVALIDOPERATION is returned if type is GLUNSIGNEDINT8888EXT
and format is neither GLRGBA nor GLABGREXT.
GLUINVALIDOPERATION is returned if type is
GLUNSIGNEDINT1010102EXT and format is neither GLRGBA nor
GLABGREXT.
GLUINVALIDOPERATION is returned if format is GLABGREXT and the
GLEXTabgr extension is not supported.
GLUINVALIDOPERATION is returned if type is GLUNSIGNEDBYTE332EXT,
GLUNSIGNEDSHORT4444EXT, GLUNSIGNEDSHORT5551EXT,
GLUNSIGNEDINT8888EXT or GLUNSIGNEDINT1010102EXT and the
GLEXTpackedpixels extension is not supported.
GLUINVALIDOPERATION is returned if format is GLDEPTHCOMPONENT and the
GLSGIXdepthtexture extension is not supported.
SEE ALSO
glDrawPixels, glTexImage1D, glTexImage2D, gluBuild2DMipmaps,
gluErrorString, glGetTexImage, glGetTexLevelParameter.
Page 3