Builds a 3-D mipmap.
OpenGL C bindings library: libGL.a
GLint gluBuild3DMipmaps( GLenum target, GLint internalFormat, GLsizei width, GLsizei height, GLsizei depth, GLenum format, GLenum type, const void *data )
gluBuild3DMipmaps builds a series of prefiltered 3D 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 gluErrorString).
Initially, the width, height and depth of data are checked to see if they are a power of two. If not, a copy of data (not 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, height or depth is exactly between powers of 2, then the copy of data will scale upwards.) 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 dimensions 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 log2(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 subroutine for a description of the acceptable values for format parameter. See the glDrawPixels subroutine for a description of the acceptable values for type parameter.
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)).
GLU_INVALID_VALUE is returned if width, height or depth are < 1.
GLU_INVALID_ENUM is returned if internalFormat, 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.
| /usr/include/GL/gl.h | Contains C language constraints, variable type definitions, and ANSI function prototypes for OpenGL. |