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GLUBUILD1DMIPMAPS(3G)                                                                  GLUBUILD1DMIPMAPS(3G)



NAME
       gluBuild1DMipmaps - builds a one-dimensional 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 GL_TEXTURE_1D.

       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           Specifies the width, in pixels, of the texture 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, 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
       gluBuild1DMipmaps  builds  a series of prefiltered one-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  of  data  is  checked to see if it is a power of 2. If not, a copy of data is
       scaled up or down to the nearest power of 2. (If width 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 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  1x1  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 {log sub 2}(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 parame-ter. parameter.
       ter. 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 maxi-mum maximum
       mum level can be derived from the formula log2(width).

       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, and if the GLU
       version is 1.3 or greater.

ERRORS
       GLU_INVALID_VALUE is returned if width is < 1.

       GLU_INVALID_ENUM is returned if format or type are 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),  gluBuild2DMipmaps(3G),  gluBuild3DMipmaps(3G),
       gluErrorString(3G),        glGetTexImage(3G),         glGetTexLevelParameter(3G),         gluBuild1DMipmapLevels(3G),
       gluBuild2DMipmapLevels(3G), gluBuild3DMipmapLevels(3G)




                                                                                       GLUBUILD1DMIPMAPS(3G)