gluBuild2DMipmaps man page on Solaris

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GLUBUILD2DMIPMAPS(3gl)					GLUBUILD2DMIPMAPS(3gl)

NAME
       gluBuild2DMipmaps - builds a 2-D mipmap

C SPECIFICATION
       GLint gluBuild2DMipmaps( GLenum target,
				GLint internalFormat,
				GLsizei width,
				GLsizei height,
				GLenum format,
				GLenum type,
				const void *data )

PARAMETERS
       target	       Specifies the target texture. Must be GL_TEXTURE_2D.

       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_LUMI‐
		       NANCE_ALPHA,	  GL_LUMINANCE4_ALPHA4,	      GL_LUMI‐
		       NANCE6_ALPHA2,	   GL_LUMINANCE8_ALPHA8,      GL_LUMI‐
		       NANCE12_ALPHA4,	  GL_LUMINANCE12_ALPHA12,     GL_LUMI‐
		       NANCE16_ALPHA16, GL_INTENSITY, GL_INTENSITY4, GL_INTEN‐
		       SITY8,	 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, height   Specifies the width and height, respectively, in pixels
		       of the texture image.

       format	       Specifies  the  format  of the pixel data.  Must be one
		       of:   GL_COLOR_INDEX,   GL_RED,	 GL_GREEN,    GL_BLUE,
		       GL_ALPHA,  GL_RGB,  GL_RGBA, GL_LUMINANCE, and GL_LUMI‐
		       NANCE_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,
		       or GL_FLOAT.

       data	       Specifies a pointer to the image data in memory.

DESCRIPTION
       gluBuild2DMipmaps  builds  a  series of prefiltered 2-D texture maps of
       decreasing resolutions called a mipmap. This is used for the antialias‐
       ing of texture mapped primitives.

       A  return  value	 of 0 indicates success, otherwise a GLU error code is
       returned (see gluErrorString).

       Initially, the width and height 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 or height is exactly
       between powers of 2, then the copy of data will	scale  upwards.)   For
       example, if width is 57 and height is 23 then a copy of data will scale
       up to 64 and down to 16, respectively, before mipmapping takes place.

       Then, proxy textures (see glTexImage2D) are used to  determine  if  the
       implementation  can  fit the requested texture. If not, both dimensions
       are continually halved until it fits. (If the OpenGL version is <= 1.0,
       both  maximum  texture  dimensions are clamped to the value returned by
       glGetIntegerv with the argument GL_MAX_TEXTURE_SIZE.)

       Next, a series of mipmap levels is built by decimating a copy  of  data
       in half along both dimensions until size 1x1 is reached. At each level,
       each texel in the halved mipmap level is an average of the  correspond‐
       ing four texels in the larger mipmap level. (In the case of rectangular
       images, the decimation will ultimately reach an N x 1 or 1 x N configu‐
       ration. Here, two texels are averaged instead.)

       glTexImage2D is called to load each of these mipmap levels.  Level 0 is
       a copy of data.	The highest  level  is	log2(max(width,height)).   For
       example,	 if  width  is	64 and height is 16 and the implementation can
       store a texture of this size, the following mipmap  levels  are	built:
       64x16,  32x8, 16x4, 8x2, 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  format. See the glDrawPixels reference page for a descrip‐
       tion of the acceptable values for type.

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 & height actually used at level 0.  (The width &  height  may
       not  be equal to width & height 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)).

ERRORS
       GLU_INVALID_VALUE is returned if width or height are < 1.

       GLU_INVALID_ENUM	 is returned if internalFormat, format or type are not
       legal.

SEE ALSO
       glDrawPixels, glTexImage1D, glTexImage2D, gluBuild1DMipmaps,
       gluErrorString, gluScaleImage

				   15 Mar 97		GLUBUILD2DMIPMAPS(3gl)
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