fgluBuild1DMipmaps(3G)

NAME
     fgluBuild1DMipmaps - builds a 1-D mipmap


FORTRAN SPECIFICATION
     INTEGER*4 fgluBuild1DMipmaps( INTEGER*4 target,
                                   INTEGER*4 internalFormat,
                                   INTEGER*4 width,
                                   INTEGER*4 format,
                                   INTEGER*4 type,
                                   void data )


PARAMETERS
     target          Specifies the target texture.  Must be GL_TEXTURE_1D.

     internalFormat  Requests the internal storage format of the texture
                     image.  Must be 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_LUMINANCE,
                     GL_LUMINANCE_ALPHA and GL_ABGR_EXT.

     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_EXT,
                     GL_UNSIGNED_SHORT_4_4_4_4_EXT,
                     GL_UNSIGNED_SHORT_5_5_5_1_EXT,
                     GL_UNSIGNED_INT_8_8_8_8_EXT, and
                     GL_UNSIGNED_INT_10_10_10_2_EXT.

     data            Specifies a pointer to the image data in memory.

DESCRIPTION
     fgluBuild1DMipmaps 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 fgluErrorString).

     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
     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_EXT
     and format is not GL_RGB.

     GLU_INVALID_OPERATION is returned if type is
     GL_UNSIGNED_SHORT_4_4_4_4_EXT and format is neither GL_RGBA nor
     GL_ABGR_EXT.
     GLU_INVALID_OPERATION is returned if type is
     GL_UNSIGNED_SHORT_5_5_5_1_EXT and format is neither GL_RGBA nor
     GL_ABGR_EXT.

     GLU_INVALID_OPERATION is returned if type is GL_UNSIGNED_INT_8_8_8_8_EXT
     and format is neither GL_RGBA nor GL_ABGR_EXT.

     GLU_INVALID_OPERATION is returned if type is
     GL_UNSIGNED_INT_10_10_10_2_EXT and format is neither GL_RGBA nor
     GL_ABGR_EXT.

     GLU_INVALID_OPERATION is returned if format is GL_ABGR_EXT and the
     GL_EXT_abgr extension is not supported.

     GLU_INVALID_OPERATION is returned if type is GL_UNSIGNED_BYTE_3_3_2_EXT,
     GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT,
     GL_UNSIGNED_INT_8_8_8_8_EXT or GL_UNSIGNED_INT_10_10_10_2_EXT and the
     GL_EXT_packed_pixels extension is not supported.

     GLU_INVALID_OPERATION is returned if format is GL_DEPTH_COMPONENT and the
     GL_SGIX_depth_texture extension is not supported.

SEE ALSO
     glDrawPixels, glTexImage1D, glTexImage2D, fgluBuild2DMipmaps,
     fgluErrorString, glGetTexImage, glGetTexLevelParameter.