1GLGETTEXIMAGE(3G) OpenGL Manual GLGETTEXIMAGE(3G)
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6 glGetTexImage - return a texture image
7
9 void glGetTexImage(GLenum target, GLint level, GLenum format,
10 GLenum type, GLvoid * img);
11
13 target
14 Specifies which texture is to be obtained. GL_TEXTURE_1D,
15 GL_TEXTURE_2D, GL_TEXTURE_3D, GL_TEXTURE_1D_ARRAY,
16 GL_TEXTURE_2D_ARRAY, GL_TEXTURE_RECTANGLE,
17 GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X,
18 GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y,
19 GL_TEXTURE_CUBE_MAP_POSITIVE_Z, and GL_TEXTURE_CUBE_MAP_NEGATIVE_Z
20 are accepted.
21 level
23 Specifies the level-of-detail number of the desired image. Level 0
24 is the base image level. Level n is the nth mipmap reduction image.
25 format
27 Specifies a pixel format for the returned data. The supported
28 formats are GL_STENCIL_INDEX, GL_DEPTH_COMPONENT, GL_DEPTH_STENCIL,
29 GL_RED, GL_GREEN, GL_BLUE, GL_RG, GL_RGB, GL_RGBA, GL_BGR, GL_BGRA,
30 GL_RED_INTEGER, GL_GREEN_INTEGER, GL_BLUE_INTEGER, GL_RG_INTEGER,
31 GL_RGB_INTEGER, GL_RGBA_INTEGER, GL_BGR_INTEGER, GL_BGRA_INTEGER.
32 type
34 Specifies a pixel type for the returned data. The supported types
35 are GL_UNSIGNED_BYTE, GL_BYTE, GL_UNSIGNED_SHORT, GL_SHORT,
36 GL_UNSIGNED_INT, GL_INT, GL_HALF_FLOAT, GL_FLOAT,
37 GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV,
38 GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_5_6_5_REV,
39 GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_4_4_4_4_REV,
40 GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV,
41 GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV,
42 GL_UNSIGNED_INT_10_10_10_2, GL_UNSIGNED_INT_2_10_10_10_REV,
43 GL_UNSIGNED_INT_24_8, GL_UNSIGNED_INT_10F_11F_11F_REV,
44 GL_UNSIGNED_INT_5_9_9_9_REV, and GL_FLOAT_32_UNSIGNED_INT_24_8_REV.
45 img
47 Returns the texture image. Should be a pointer to an array of the
48 type specified by type.
49
51 glGetTexImage returns a texture image into img. target specifies
52 whether the desired texture image is one specified by glTexImage1D()
53 (GL_TEXTURE_1D), glTexImage2D() (GL_TEXTURE_1D_ARRAY,
54 GL_TEXTURE_RECTANGLE, GL_TEXTURE_2D or any of GL_TEXTURE_CUBE_MAP_*),
55 or glTexImage3D() (GL_TEXTURE_2D_ARRAY, GL_TEXTURE_3D). level
56 specifies the level-of-detail number of the desired image. format and
57 type specify the format and type of the desired image array. See the
58 reference page for glTexImage1D() for a description of the acceptable
59 values for the format and type parameters, respectively.
60 If a non-zero named buffer object is bound to the GL_PIXEL_PACK_BUFFER
62 target (see glBindBuffer()) while a texture image is requested, img is
63 treated as a byte offset into the buffer object's data store.
64 To understand the operation of glGetTexImage, consider the selected
66 internal four-component texture image to be an RGBA color buffer the
67 size of the image. The semantics of glGetTexImage are then identical to
68 those of glReadPixels(), with the exception that no pixel transfer
69 operations are performed, when called with the same format and type,
70 with x and y set to 0, width set to the width of the texture image and
71 height set to 1 for 1D images, or to the height of the texture image
72 for 2D images.
73 If the selected texture image does not contain four components, the
75 following mappings are applied. Single-component textures are treated
76 as RGBA buffers with red set to the single-component value, green set
77 to 0, blue set to 0, and alpha set to 1. Two-component textures are
78 treated as RGBA buffers with red set to the value of component zero,
79 alpha set to the value of component one, and green and blue set to 0.
80 Finally, three-component textures are treated as RGBA buffers with red
81 set to component zero, green set to component one, blue set to
82 component two, and alpha set to 1.
83 To determine the required size of img, use glGetTexLevelParameter() to
85 determine the dimensions of the internal texture image, then scale the
86 required number of pixels by the storage required for each pixel, based
87 on format and type. Be sure to take the pixel storage parameters into
88 account, especially GL_PACK_ALIGNMENT.
89
91 If an error is generated, no change is made to the contents of img.
92 glGetTexImage returns the texture image for the active texture unit.
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96 GL_INVALID_ENUM is generated if target, format, or type is not an
97 accepted value.
98 GL_INVALID_VALUE is generated if level is less than 0.
100 GL_INVALID_VALUE may be generated if level is greater than log 2 max,
102 where max is the returned value of GL_MAX_TEXTURE_SIZE.
103 GL_INVALID_OPERATION is returned if type is one of
105 GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV,
106 GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_5_6_5_REV, or
107 GL_UNSIGNED_INT_10F_11F_11F_REV and format is not GL_RGB.
108 GL_INVALID_OPERATION is returned if type is one of
110 GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_4_4_4_4_REV,
111 GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV,
112 GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV,
113 GL_UNSIGNED_INT_10_10_10_2, GL_UNSIGNED_INT_2_10_10_10_REV, or
114 GL_UNSIGNED_INT_5_9_9_9_REV and format is neither GL_RGBA or GL_BGRA.
115 GL_INVALID_OPERATION is generated if a non-zero buffer object name is
117 bound to the GL_PIXEL_PACK_BUFFER target and the buffer object's data
118 store is currently mapped.
119 GL_INVALID_OPERATION is generated if a non-zero buffer object name is
121 bound to the GL_PIXEL_PACK_BUFFER target and the data would be packed
122 to the buffer object such that the memory writes required would exceed
123 the data store size.
124 GL_INVALID_OPERATION is generated if a non-zero buffer object name is
126 bound to the GL_PIXEL_PACK_BUFFER target and img is not evenly
127 divisible into the number of bytes needed to store in memory a datum
128 indicated by type.
129
131 glGetTexLevelParameter() with argument GL_TEXTURE_WIDTH
132 glGetTexLevelParameter() with argument GL_TEXTURE_HEIGHT
134 glGetTexLevelParameter() with argument GL_TEXTURE_INTERNAL_FORMAT
136 glGet() with arguments GL_PACK_ALIGNMENT and others
138 glGet() with argument GL_PIXEL_PACK_BUFFER_BINDING
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142 glActiveTexture(), glReadPixels(), glTexImage1D(), glTexImage2D(),
143 glTexImage3D(), glTexSubImage1D(), glTexSubImage2D(),
144 glTexSubImage3D(), glTexParameter()
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147 Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010 Khronos
148 Group. This document is licensed under the SGI Free Software B License.
149 For details, see http://oss.sgi.com/projects/FreeB/.
150
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