Creates 1-dimensional (1D) mipmaps.
OpenGL C bindings library: libGL.a
GLint gluBuild1DMipmaps(GLenum target, GLint internalFormat, GLsizei width, GLenum format, GLenum type, const void *data)
The gluBuild1DMipmaps subroutine builds a series of prefiltered 1D 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 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 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 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 subroutine for a description of the acceptable values for the format parameter. See the glDrawPixels subroutine for acceptable values for the type parameter.
| target | Specifies the target texture. This value must be GL_TEXTURE_1D. |
| internalFormat | Specifies the number of color components in the texture. Values must be 1, 2, 3, or 4 or one of the following symbolic constants:
|
| width | Specifies the width, in pixels, of the texture image. |
| format | Specifies the format of the pixel data. The following symbolic values are valid: |
| (See the glTexImage1D subroutine for a description of the acceptable values for the format parameter.) | |
| type | Specifies the data type. The following data types for data are valid:
|
| (See the glDrawPixels subroutine for acceptable values for the type parameter.) | |
| data | Specifies a pointer to the image data in memory. |
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).
| /usr/include/GL/gl.h | Contains C language constraints, variable type definitions, and ANSI function prototypes for OpenGL. |
The gluBuild1DMipmaps subroutine, gluBuild2DMipmaps subroutine, gluBuild3DMipmaps subroutine, gluBuild1DMipmapLevels subroutine, gluBuild2DMipmapLevels subroutine, gluBuild3DMipmapLevels subroutine, glDrawPixels subroutine, glGetTexLevelParameter subroutine, glGetTexImage subroutine, glTexImage1D subroutine, glTexImage2D subroutine, glTexImage3D subroutine .