235 lines
7.9 KiB
Plaintext
235 lines
7.9 KiB
Plaintext
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'\" e
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'\"! eqn | mmdoc
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'\"macro stdmacro
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.ds Vn Version 1.2
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.ds Dt 6 March 1997
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.ds Re Release 1.2.0
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.ds Dp May 02 11:53
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.ds Dm 37 build2dmi
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.ds Xs 35570 9 build2dmipmaplevels.gl
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.TH GLUBUILD2DMIPMAPLEVELS 3G
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.SH NAME
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.B "gluBuild2DMipmapLevels
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\- builds a subset of two-dimensional mipmap levels
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.SH C SPECIFICATION
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GLint \f3gluBuild2DMipmapLevels\fP(
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GLenum \fItarget\fP,
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.nf
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.ta \w'\f3GLint \fPgluBuild2DMipmapLevels( 'u
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GLint \fIinternalFormat\fP,
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GLsizei \fIwidth\fP,
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GLsizei \fIheight\fP,
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GLenum \fIformat\fP,
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GLenum \fItype\fP,
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GLint \fIlevel\fP,
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GLint \fIbase\fP,
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GLint \fImax\fP,
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const void \fI*data\fP )
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.fi
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.EQ
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delim $$
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.EN
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.SH PARAMETERS
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.TP \w'\fIinternalFormat\fP\ \ 'u
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\f2target\fP
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Specifies the target texture. Must be \%\f3GL_TEXTURE_2D\fP.
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.TP
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\f2internalFormat\fP
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Requests the internal storage of the texture image. The most
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current version of the SGI implementation of GLU does not check this
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value for validity before passing it on to the underlying OpenGL
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implementation. A value that is not accepted by the OpenGL
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implementation will lead to an OpenGL error. The benefit of not
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checking this value at the GLU level is that OpenGL extensions can add
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new internal texture formats without requiring a revision of the GLU
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implementation. Older implementations of GLU check this value and
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raise a GLU error if it is not 1, 2, 3, or 4 or one of the following
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symbolic constants:
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\%\f3GL_ALPHA\fP,
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\%\f3GL_ALPHA4\fP,
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\%\f3GL_ALPHA8\fP,
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\%\f3GL_ALPHA12\fP,
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\%\f3GL_ALPHA16\fP,
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\%\f3GL_LUMINANCE\fP,
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\%\f3GL_LUMINANCE4\fP,
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\%\f3GL_LUMINANCE8\fP,
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\%\f3GL_LUMINANCE12\fP,
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\%\f3GL_LUMINANCE16\fP,
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\%\f3GL_LUMINANCE_ALPHA\fP,
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\%\f3GL_LUMINANCE4_ALPHA4\fP,
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\%\f3GL_LUMINANCE6_ALPHA2\fP,
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\%\f3GL_LUMINANCE8_ALPHA8\fP,
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\%\f3GL_LUMINANCE12_ALPHA4\fP,
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\%\f3GL_LUMINANCE12_ALPHA12\fP,
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\%\f3GL_LUMINANCE16_ALPHA16\fP,
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\%\f3GL_INTENSITY\fP,
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\%\f3GL_INTENSITY4\fP,
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\%\f3GL_INTENSITY8\fP,
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\%\f3GL_INTENSITY12\fP,
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\%\f3GL_INTENSITY16\fP,
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\%\f3GL_RGB\fP,
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\%\f3GL_R3_G3_B2\fP,
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\%\f3GL_RGB4\fP,
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\%\f3GL_RGB5\fP,
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\%\f3GL_RGB8\fP,
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\%\f3GL_RGB10\fP,
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\%\f3GL_RGB12\fP,
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\%\f3GL_RGB16\fP,
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\%\f3GL_RGBA\fP,
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\%\f3GL_RGBA2\fP,
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\%\f3GL_RGBA4\fP,
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\%\f3GL_RGB5_A1\fP,
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\%\f3GL_RGBA8\fP,
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\%\f3GL_RGB10_A2\fP,
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\%\f3GL_RGBA12\fP or
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\%\f3GL_RGBA16\fP.
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.TP
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\f2width\fP, \f2height\fP
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Specifies the width and height, respectively, in pixels of the texture image.
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These should be a power of 2.
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.TP
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\f2format\fP
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Specifies the of the pixel data.
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Must be one of
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\%\f3GL_COLOR_INDEX\fP,
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\%\f3GL_DEPTH_COMPONENT\fP,
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\%\f3GL_RED\fP,
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\%\f3GL_GREEN\fP,
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\%\f3GL_BLUE\fP,
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\%\f3GL_ALPHA\fP,
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\%\f3GL_RGB\fP,
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\%\f3GL_RGBA\fP,
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\%\f3GL_BGR\fP,
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\%\f3GL_BGRA\fP,
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\%\f3GL_LUMINANCE\fP, or
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\%\f3GL_LUMINANCE_ALPHA\fP.
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.TP
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\f2type\fP
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Specifies the data type for \f2data\fP.
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Must be one of
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\%\f3GL_UNSIGNED_BYTE\fP,
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\%\f3GL_BYTE\fP,
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\%\f3GL_BITMAP\fP,
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\%\f3GL_UNSIGNED_SHORT\fP,
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\%\f3GL_SHORT\fP,
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\%\f3GL_UNSIGNED_INT\fP,
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\%\f3GL_INT\fP,
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\%\f3GL_FLOAT\fP,
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\%\f3GL_UNSIGNED_BYTE_3_3_2\fP,
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\%\f3GL_UNSIGNED_BYTE_2_3_3_REV\fP,
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\%\f3GL_UNSIGNED_SHORT_5_6_5\fP,
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\%\f3GL_UNSIGNED_SHORT_5_6_5_REV\fP,
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\%\f3GL_UNSIGNED_SHORT_4_4_4_4\fP,
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\%\f3GL_UNSIGNED_SHORT_4_4_4_4_REV\fP,
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\%\f3GL_UNSIGNED_SHORT_5_5_5_1\fP,
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\%\f3GL_UNSIGNED_SHORT_1_5_5_5_REV\fP,
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\%\f3GL_UNSIGNED_INT_8_8_8_8\fP,
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\%\f3GL_UNSIGNED_INT_8_8_8_8_REV\fP,
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\%\f3GL_UNSIGNED_INT_10_10_10_2\fP or
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\%\f3GL_UNSIGNED_INT_2_10_10_10_REV\fP.
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.TP
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\f2level\fP
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Specifies the mipmap level of the image data.
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.TP
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\f2base\fP
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Specifies the minimum mipmap level to pass to \f3glTexImage2D\fP.
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.TP
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\f2max\fP
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Specifies the maximum mipmap level to pass to \f3glTexImage2D\fP.
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.TP
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\f2data\fP
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Specifies a pointer to the image data in memory.
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.SH DESCRIPTION
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\%\f3gluBuild2DMipmapLevels\fP builds a subset of prefiltered two-dimensional texture maps of decreasing
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resolutions called a mipmap. This is used for the antialiasing of
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texture mapped primitives.
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.P
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A return value of zero indicates success, otherwise a GLU error code is
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returned (see \%\f3gluErrorString\fP).
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.P
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A series of mipmap levels from \f2base\fP to \f2max\fP is built by decimating
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\f2data\fP in half along
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both dimensions until size $1 ~times~ 1$ is reached. At each level, each texel in the
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halved mipmap level is an average of the corresponding four texels in the larger
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mipmap level. (In the case of rectangular images, the decimation will ultimately
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reach an $N ~times~ 1$ or $1 ~times~ N$ configuration. Here, two texels are
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averaged instead.)
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\f3glTexImage2D\fP is called to load these mipmap levels from \f2base\fP
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to \f2max\fP. If \f2max\fP is larger than the highest mipmap level for the
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texture of the specified size, then a GLU error code is returned (see
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\%\f3gluErrorString\fP) and nothing is loaded.
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.P
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For example, if \f2level\fP is 2 and \f2width\fP is 16 and \f2height\fP is 8, the
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following levels are possible: $16 ~times~ 8$, $8 ~times~ 4$, $4 ~times~ 2$,
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$2 ~times~ 1$, $1 ~times~ 1$. These correspond to levels 2 through 6
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respectively. If \f2base\fP is 3 and \f2max\fP is 5, then only mipmap levels
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$8 ~times~ 4$, $4 ~times~ 2$ and $2 ~times~ 1$ are loaded. However, if \f2max\fP
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is 7 then an error is returned and nothing is loaded since \f2max\fP is
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larger than the highest mipmap level which is, in this case, 6.
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.P
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The highest mipmap level can be derived from the formula
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log2(max(\f2width\fP,\f2height\fP)*(2^\f2level\fP)).
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.P
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See the \f3glTexImage1D\fP reference page for a description of the
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acceptable values for \f2format\fP parameter. See the \f3glDrawPixels\fP
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reference page for a description of the acceptable values
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for \f2type\fP parameter.
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.SH NOTES
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\%\f3gluBuild2DMipmapLevels\fP is only available if the GLU version is 1.3 or greater.
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.P
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Formats \%\f3GL_BGR\fP, and \%\f3GL_BGRA\fP, and types
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\%\f3GL_UNSIGNED_BYTE_3_3_2\fP,
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\%\f3GL_UNSIGNED_BYTE_2_3_3_REV\fP,
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\%\f3GL_UNSIGNED_SHORT_5_6_5\fP,
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\%\f3GL_UNSIGNED_SHORT_5_6_5_REV\fP,
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\%\f3GL_UNSIGNED_SHORT_4_4_4_4\fP,
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\%\f3GL_UNSIGNED_SHORT_4_4_4_4_REV\fP,
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\%\f3GL_UNSIGNED_SHORT_5_5_5_1\fP,
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\%\f3GL_UNSIGNED_SHORT_1_5_5_5_REV\fP,
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\%\f3GL_UNSIGNED_INT_8_8_8_8\fP,
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\%\f3GL_UNSIGNED_INT_8_8_8_8_REV\fP,
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\%\f3GL_UNSIGNED_INT_10_10_10_2\fP, and
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\%\f3GL_UNSIGNED_INT_2_10_10_10_REV\fP are only available if the GL version
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is 1.2 or greater.
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.SH ERRORS
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\%\f3GLU_INVALID_VALUE\fP is returned if \f2level\fP > \f2base\fP, \f2base\fP < 0,
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\f2max\fP < \f2base\fP or \f2max\fP is > the highest mipmap level for \f2data\fP.
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.P
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\%\f3GLU_INVALID_VALUE\fP is returned if \f2width\fP or \f2height\fP is < 1.
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.P
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\%\f3GLU_INVALID_ENUM\fP is returned if \f2internalFormat\fP, \f2format\fP, or \f2type\fP is not
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legal.
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.P
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\%\f3GLU_INVALID_OPERATION\fP is returned if \f2type\fP is \%\f3GL_UNSIGNED_BYTE_3_3_2\fP or \%\f3GL_UNSIGNED_BYTE_2_3_3_REV\fP
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and \f2format\fP is not \%\f3GL_RGB\fP.
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.P
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\%\f3GLU_INVALID_OPERATION\fP is returned if \f2type\fP is \%\f3GL_UNSIGNED_SHORT_5_6_5\fP or \%\f3GL_UNSIGNED_SHORT_5_6_5_REV\fP
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and \f2format\fP is not \%\f3GL_RGB\fP.
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.P
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\%\f3GLU_INVALID_OPERATION\fP is returned if \f2type\fP is \%\f3GL_UNSIGNED_SHORT_4_4_4_4\fP or \%\f3GL_UNSIGNED_SHORT_4_4_4_4_REV\fP
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and \f2format\fP is neither \%\f3GL_RGBA\fP nor \%\f3GL_BGRA\fP.
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.P
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\%\f3GLU_INVALID_OPERATION\fP is returned if \f2type\fP is \%\f3GL_UNSIGNED_SHORT_5_5_5_1\fP or \%\f3GL_UNSIGNED_SHORT_1_5_5_5_REV\fP
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and \f2format\fP is neither \%\f3GL_RGBA\fP nor \%\f3GL_BGRA\fP.
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.P
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\%\f3GLU_INVALID_OPERATION\fP is returned if \f2type\fP is \%\f3GL_UNSIGNED_INT_8_8_8_8\fP or \%\f3GL_UNSIGNED_INT_8_8_8_8_REV\fP
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and \f2format\fP is neither \%\f3GL_RGBA\fP nor \%\f3GL_BGRA\fP.
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.P
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\%\f3GLU_INVALID_OPERATION\fP is returned if \f2type\fP is \%\f3GL_UNSIGNED_INT_10_10_10_2\fP or \%\f3GL_UNSIGNED_INT_2_10_10_10_REV\fP
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and \f2format\fP is neither \%\f3GL_RGBA\fP nor \%\f3GL_BGRA\fP.
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.SH SEE ALSO
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\f3glDrawPixels(3G)\fP,
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\f3glTexImage1D(3G)\fP,
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\f3glTexImage2D(3G)\fP,
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\f3glTexImage3D(3G)\fP,
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\%\f3gluBuild1DMipmaps(3G)\fP,
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\%\f3gluBuild2DMipmaps(3G)\fP,
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\%\f3gluBuild3DMipmaps(3G)\fP,
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\%\f3gluErrorString(3G)\fP,
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\f3glGetTexImage(3G)\fP,
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\f3glGetTexLevelParameter(3G)\fP,
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\%\f3gluBuild1DMipmapLevels(3G)\fP,
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\%\f3gluBuild3DMipmapLevels(3G)\fP
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