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GLUBUILD3DMIPMAPS(3G)                                                                  GLUBUILD3DMIPMAPS(3G)



NAME
       gluBuild3DMipmaps - builds a three-dimensional mipmap


C SPECIFICATION
       GLint gluBuild3DMipmaps( GLenum target,
                                GLint internalFormat,
                                GLsizei width,
                                GLsizei height,
                                GLsizei depth,
                                GLenum format,
                                GLenum type,
                                const void *data )


PARAMETERS
       target          Specifies the target texture.  Must be GL_TEXTURE_3D.

       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, depth
                       Specifies  in  pixels the width, height and depth respectively, in pixels of the tex-ture texture
                       ture image.

       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.

       data            Specifies a pointer to the image data in memory.

DESCRIPTION
       gluBuild3DMipmaps builds a series of prefiltered three-dimensional texture maps of decreasing resolu-tions resolutions
       tions 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).

       Initially, the width, height and depth of data are checked to see if they are a power of 2. If not, a
       copy  of  data (not data), is scaled up or down to the nearest power of 2. (If width, height or depth
       is exactly between powers of 2, then the copy of data will scale upwards.) This copy will be used for
       subsequent  mipmapping  operations  described  below.   For example, if width is 57, height is 23 and
       depth is 24 then a copy of data will scale up to 64 in width, down to 16 in height and up  to  32  in
       depth, before mipmapping takes place.

       Then,  proxy  textures  (see  glTexImage3D)  are  used to determine if the implementation can fit the
       requested texture. If not, all three dimensions are continually halved until it fits.

       Next, a series of mipmap levels is built by decimating a copy of data in half along all three  dimen-sions dimensions
       sions until size 1x1x1 is reached. At each level, each texel in the halved mipmap level is an average
       of the corresponding eight texels in the larger mipmap level. (If exactly one of the dimensions is 1,
       four texels are averaged.  If exactly two of the dimensions are 1, two texels are averaged.)

       glTexImage3D  is called to load each of these mipmap levels.  Level 0 is a copy of data.  The highest
       level is {log sub 2} ( max ("width","height","depth")).  For example, if width is 64,  height  is  16
       and depth is 32, and the implementation can store a texture of this size, the following mipmap levels
       are built: 64x16x32, 32x8x16, 16x4x8, 8x2x4, 4x1x2, 2x1x1 and 1x1x1. These  correspond  to  levels  0
       through 6, respectively.

       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
       Note that there is no direct way of querying the maximum level. This can be  derived  indirectly  via
       glGetTexLevelParameter.  First, query for the width, height and depth actually used at level 0.  (The
       width, height and depth may not be equal to width, height and depth respectively since proxy textures
       might  have  scaled  them to fit the implementation.)  Then the maximum level can be derived from the
       formula log2 ( max (width,height,depth)).

       gluBuild3DMipmaps 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 width, height, or depth 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),   gluBuild3DMipmaps(3G),
       gluErrorString(3G),         glGetTexImage(3G),         glGetTexLevelParameter(3G),        gluBuild1DMipmapLevels(3G),
       gluBuild2DMipmapLevels(3G), gluBuild3DMipmapLevels(3G)




                                                                                       GLUBUILD3DMIPMAPS(3G)