1GLUBUILD2DMIPMAPS(3G) OpenGL Manual GLUBUILD2DMIPMAPS(3G)
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6 gluBuild2DMipmaps - builds a two-dimensional mipmap
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9 GLint gluBuild2DMipmaps(GLenum target, GLint internalFormat,
10 GLsizei width, GLsizei height, GLenum format,
11 GLenum type, const void * data);
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14 target
15 Specifies the target texture. Must be GLU_TEXTURE_2D.
16 internalFormat
18 Requests the internal storage format of the texture image. The most
19 current version of the SGI implementation of GLU does not check
20 this value for validity before passing it on to the underlying
21 OpenGL implementation. A value that is not accepted by the OpenGL
22 implementation will lead to an OpenGL error. The benefit of not
23 checking this value at the GLU level is that OpenGL extensions can
24 add new internal texture formats without requiring a revision of
25 the GLU implementation. Older implementations of GLU check this
26 value and raise a GLU error if it is not 1, 2, 3, or 4 or one of
27 the following symbolic constants: GLU_ALPHA, GLU_ALPHA4,
28 GLU_ALPHA8, GLU_ALPHA12, GLU_ALPHA16, GLU_LUMINANCE,
29 GLU_LUMINANCE4, GLU_LUMINANCE8, GLU_LUMINANCE12, GLU_LUMINANCE16,
30 GLU_LUMINANCE_ALPHA, GLU_LUMINANCE4_ALPHA4, GLU_LUMINANCE6_ALPHA2,
31 GLU_LUMINANCE8_ALPHA8, GLU_LUMINANCE12_ALPHA4,
32 GLU_LUMINANCE12_ALPHA12, GLU_LUMINANCE16_ALPHA16, GLU_INTENSITY,
33 GLU_INTENSITY4, GLU_INTENSITY8, GLU_INTENSITY12, GLU_INTENSITY16,
34 GLU_RGB, GLU_R3_G3_B2, GLU_RGB4, GLU_RGB5, GLU_RGB8, GLU_RGB10,
35 GLU_RGB12, GLU_RGB16, GLU_RGBA, GLU_RGBA2, GLU_RGBA4, GLU_RGB5_A1,
36 GLU_RGBA8, GLU_RGB10_A2, GLU_RGBA12, or GLU_RGBA16.
37 width, height
39 Specifies in pixels the width and height, respectively, of the
40 texture image.
41 format
43 Specifies the format of the pixel data. Must be one of
44 GLU_COLOR_INDEX, GLU_DEPTH_COMPONENT, GLU_RED, GLU_GREEN, GLU_BLUE,
45 GLU_ALPHA, GLU_RGB, GLU_RGBA, GLU_BGR, GLU_BGRA, GLU_LUMINANCE, or
46 GLU_LUMINANCE_ALPHA.
47 type
49 Specifies the data type for data. Must be one of GLU_UNSIGNED_BYTE,
50 GLU_BYTE, GLU_BITMAP, GLU_UNSIGNED_SHORT, GLU_SHORT,
51 GLU_UNSIGNED_INT, GLU_INT, GLU_FLOAT, GLU_UNSIGNED_BYTE_3_3_2,
52 GLU_UNSIGNED_BYTE_2_3_3_REV, GLU_UNSIGNED_SHORT_5_6_5,
53 GLU_UNSIGNED_SHORT_5_6_5_REV, GLU_UNSIGNED_SHORT_4_4_4_4,
54 GLU_UNSIGNED_SHORT_4_4_4_4_REV, GLU_UNSIGNED_SHORT_5_5_5_1,
55 GLU_UNSIGNED_SHORT_1_5_5_5_REV, GLU_UNSIGNED_INT_8_8_8_8,
56 GLU_UNSIGNED_INT_8_8_8_8_REV, GLU_UNSIGNED_INT_10_10_10_2, or
57 GLU_UNSIGNED_INT_2_10_10_10_REV.
58 data
60 Specifies a pointer to the image data in memory.
61
63 gluBuild2DMipmaps builds a series of prefiltered two-dimensional
64 texture maps of decreasing resolutions called a mipmap. This is used
65 for the antialiasing of texture-mapped primitives.
66 A return value of zero indicates success, otherwise a GLU error code is
68 returned (see gluErrorString()).
69 Initially, the width and height of data are checked to see if they are
71 a power of 2. If not, a copy of data (not data), is scaled up or down
72 to the nearest power of 2. This copy will be used for subsequent
73 mipmapping operations described below. (If width or height is exactly
74 between powers of 2, then the copy of data will scale upwards.) For
75 example, if width is 57 and height is 23, then a copy of data will
76 scale up to 64 in width and down to 16 in depth, before mipmapping
77 takes place.
78 Then, proxy textures (see glTexImage2D()) are used to determine if the
80 implementation can fit the requested texture. If not, both dimensions
81 are continually halved until it fits. (If the OpenGL version is \(<=
82 1.0, both maximum texture dimensions are clamped to the value returned
83 by glGetIntegerv() with the argument GLU_MAX_TEXTURE_SIZE.)
84 Next, a series of mipmap levels is built by decimating a copy of data
86 in half along both dimensions until size 1 × 1 is reached. At each
87 level, each texel in the halved mipmap level is an average of the
88 corresponding four texels in the larger mipmap level. (In the case of
89 rectangular images, the decimation will ultimately reach an N × 1 or 1
90 × N configuration. Here, two texels are averaged instead.)
91 glTexImage2D() is called to load each of these mipmap levels. Level 0
93 is a copy of data. The highest level is log 2 max width height. For
94 example, if width is 64 and height is 16 and the implementation can
95 store a texture of this size, the following mipmap levels are built: 64
96 × 16, 32 × 8, 16 × 4, 8 × 2, 4 × 1, 2 × 1, and 1 × 1 These correspond
97 to levels 0 through 6, respectively.
98 See the glTexImage1D() reference page for a description of the
100 acceptable values for format parameter. See the glDrawPixels()
101 reference page for a description of the acceptable values for type
102 parameter.
103
105 Note that there is no direct way of querying the maximum level. This
106 can be derived indirectly via glGetTexLevelParameter(). First, query
107 for the width and height actually used at level 0. (The width and
108 height may not be equal to width and height respectively since proxy
109 textures might have scaled them to fit the implementation.) Then the
110 maximum level can be derived from the formula log 2 max width
111 height.
112 Formats GLU_BGR, and GLU_BGRA, and types GLU_UNSIGNED_BYTE_3_3_2,
114 GLU_UNSIGNED_BYTE_2_3_3_REV, GLU_UNSIGNED_SHORT_5_6_5,
115 GLU_UNSIGNED_SHORT_5_6_5_REV, GLU_UNSIGNED_SHORT_4_4_4_4,
116 GLU_UNSIGNED_SHORT_4_4_4_4_REV, GLU_UNSIGNED_SHORT_5_5_5_1,
117 GLU_UNSIGNED_SHORT_1_5_5_5_REV, GLU_UNSIGNED_INT_8_8_8_8,
118 GLU_UNSIGNED_INT_8_8_8_8_REV, GLU_UNSIGNED_INT_10_10_10_2, and
119 GLU_UNSIGNED_INT_2_10_10_10_REV are only available if the GL version is
120 1.2 or greater and if the GLU version is 1.3 or greater.
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123 GLU_INVALID_VALUE is returned if width or height is < 1.
124 GLU_INVALID_ENUM is returned if internalFormat, format, or type is not
126 legal.
127 GLU_INVALID_OPERATION is returned if type is GLU_UNSIGNED_BYTE_3_3_2 or
129 GLU_UNSIGNED_BYTE_2_3_3_REV and format is not GLU_RGB.
130 GLU_INVALID_OPERATION is returned if type is GLU_UNSIGNED_SHORT_5_6_5
132 or GLU_UNSIGNED_SHORT_5_6_5_REV and format is not GLU_RGB.
133 GLU_INVALID_OPERATION is returned if type is GLU_UNSIGNED_SHORT_4_4_4_4
135 or GLU_UNSIGNED_SHORT_4_4_4_4_REV and format is neither GLU_RGBA nor
136 GLU_BGRA.
137 GLU_INVALID_OPERATION is returned if type is GLU_UNSIGNED_SHORT_5_5_5_1
139 or GLU_UNSIGNED_SHORT_1_5_5_5_REV and format is neither GLU_RGBA nor
140 GLU_BGRA.
141 GLU_INVALID_OPERATION is returned if type is GLU_UNSIGNED_INT_8_8_8_8
143 or GLU_UNSIGNED_INT_8_8_8_8_REV and format is neither GLU_RGBA nor
144 GLU_BGRA.
145 GLU_INVALID_OPERATION is returned if type is
147 GLU_UNSIGNED_INT_10_10_10_2 or GLU_UNSIGNED_INT_2_10_10_10_REV and
148 format is neither GLU_RGBA nor GLU_BGRA.
149
151 gluBuild1DMipmapLevels(), gluBuild1DMipmaps(),
152 gluBuild2DMipmapLevels(), gluBuild3DMipmapLevels(),
153 gluBuild3DMipmaps(), gluErrorString(), glDrawPixels(), glGetTexImage(),
154 glGetTexLevelParameter(), glTexImage1D(), glTexImage2D(),
155 glTexImage3D()
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158 Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed
159 under the SGI Free Software B License. For details, see
160 http://oss.sgi.com/projects/FreeB/.
161
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