error = glu.Build2DMipmaps(iformat, width, height, format, type, pixels)
glu.Build2DMipmaps() builds a series of prefiltered 2D texture maps of decreasing resolution. Mipmaps can be used so
that textures don't appear aliased.
A return value of 0 indicates success. Otherwise a GLU error code is returned (See glu.ErrorString for details.).
glu.Build2DMipmaps() first check whether width and height of pixels are both powers of 2. If not, glu.Build2DMipmaps() scales a
copy of pixels up or down to the nearest power of 2. This copy is then used as the base for subsequent mipmapping operations. For
example, if width is 57 and height is 23, then a copy of pixels scales up to 64 and down to 16, respectively, before mipmapping
takes place. (If width or height is exactly between powers of 2, the copy of data is scaled upward.)
If the GL version is 1.1 or greater, glu.Build2DMipmaps() then uses proxy textures (See gl.TexImage2D for details.) to determine
whether there's enough room for the requested texture in the implementation. If not, width is halved (and halved again) until it fits.
glu.Build2DMipmaps() then uses proxy textures (See gl.TexImage2D for details.) to determine if the implementation can store the
requested texture in texture memory. If not, both dimensions are continually halved until it fits.
Next, glu.Build2DMipmaps() builds a series of images; it halves a copy of type (or a scaled version of type, if necessary) along
both dimensions until size 1x1 is reached. At each level, each texel in the halved mipmap is an average of the corresponding four
texels in the larger mipmap. (In the case of rectangular images, halving the images repeatedly eventually results in an n*1 or 1*n
configuration. Here, two texels are averaged instead.)
gl.TexImage2D() is called to load each of these images by level. If width and height are both powers of 2
which fit in the implementation, level 0 is a copy of pixels, and the highest level is log2(max(width, height)). For example, if
width is 64 and height is 16, the following mipmaps are built: 64x16, 32x8, 16x4, 8x2, 4x1, 2x1 and 1x1. These correspond to levels
0 through 6, respectively.
iformat specifies the internal format of the texture image. See Internal pixel formats for details.
This can also be one of the special values 1, 2, 3, or 4.
format must be one of #GL_COLOR_INDEX, #GL_RED, #GL_GREEN, #GL_BLUE, #GL_ALPHA, #GL_RGB, #GL_RGBA, #GL_LUMINANCE, or #GL_LUMINANCE_ALPHA
type must be one of #GL_UNSIGNED_BYTE, #GL_BYTE, #GL_BITMAP, #GL_UNSIGNED_SHORT, #GL_SHORT, #GL_UNSIGNED_INT, #GL_INT, or #GL_FLOAT.
Please note that this command operates directly with memory pointers. There is also a version which works with tables instead of memory pointers, but this is slower of course. See glu.BuildMipmaps for details. See Working with pointers for details on how to use memory pointers with Hollywood.
Please consult an OpenGL reference manual for more information.
pixels (see above)