Provided by: opengl-4-man-doc_1.0~svn33624-1_all 
NAME
glGetTextureSubImage - retrieve a sub-region of a texture image from a texture object
C SPECIFICATION
void glGetTextureSubImage(GLuint texture, GLint level, GLint xoffset, GLint yoffset,
GLint zoffset, GLsizei width, GLsizei height, GLsizei depth,
GLenum format, GLenum type, GLsizei bufSize, void *pixels);
PARAMETERS
texture
Specifies the name of the source texture object. Must be GL_TEXTURE_1D,
GL_TEXTURE_1D_ARRAY, GL_TEXTURE_2D, GL_TEXTURE_2D_ARRAY, GL_TEXTURE_3D,
GL_TEXTURE_CUBE_MAP, GL_TEXTURE_CUBE_MAP_ARRAY or GL_TEXTURE_RECTANGLE. In specific,
buffer and multisample textures are not permitted.
level
Specifies the level-of-detail number. Level 0 is the base image level. Level $n$ is
the $n$th mipmap reduction image.
xoffset
Specifies a texel offset in the x direction within the texture array.
yoffset
Specifies a texel offset in the y direction within the texture array.
zoffset
Specifies a texel offset in the z direction within the texture array.
width
Specifies the width of the texture subimage.
height
Specifies the height of the texture subimage.
depth
Specifies the depth of the texture subimage.
format
Specifies the format of the pixel data. The following symbolic values are accepted:
GL_RED, GL_RG, GL_RGB, GL_BGR, GL_RGBA, GL_BGRA, GL_DEPTH_COMPONENT and
GL_STENCIL_INDEX.
type
Specifies the data type of the pixel data. The following symbolic values are accepted:
GL_UNSIGNED_BYTE, GL_BYTE, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT, GL_INT,
GL_FLOAT, GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV, GL_UNSIGNED_SHORT_5_6_5,
GL_UNSIGNED_SHORT_5_6_5_REV, GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_4_4_4_4_REV,
GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV, GL_UNSIGNED_INT_8_8_8_8,
GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2, and
GL_UNSIGNED_INT_2_10_10_10_REV.
bufSize
Specifies the size of the buffer to receive the retrieved pixel data.
pixels
Returns the texture subimage. Should be a pointer to an array of the type specified by
type.
DESCRIPTION
glGetTextureSubImage returns a texture subimage into pixels.
texture is the name of the source texture object and must not be a buffer or multisample
texture. The effective target parameter is the value of GL_TEXTURE_TARGET for texture.
Level, format, type and pixels have the same meaning as for glGetTexImage. bufSize is the
size of the buffer to receive the retrieved pixel data.
For cube map textures, the behavior is as though GetTextureImage were called, but only
texels from the requested cube map faces (selected by zoffset and depth, as described
below) were returned.
xoffset, yoffset and zoffset values indicate the position of the subregion to return.
width, height and depth indicate the size of the region to return. These parameters have
the same meaning as for glTexSubImage3D, though for one- and two-dimensional textures
there are extra restrictions, described in the errors section below.
For one-dimensional array textures, yoffset is interpreted as the first layer to access
and height is the number of layers to access.
For two-dimensional array textures, zoffset is interpreted as the first layer to access
and depth is the number of layers to access.
Cube map textures are treated as an array of six slices in the z-dimension, where the
value of zoffset is interpreted as specifying the cube map face for the corresponding
layer (as presented in the table below) and depth is the number of faces to access:
┌─────────────┬────────────────────────────────┐
│Layer number │ Cube Map Face │
├─────────────┼────────────────────────────────┤
│0 │ GL_TEXTURE_CUBE_MAP_POSITIVE_X │
├─────────────┼────────────────────────────────┤
│1 │ GL_TEXTURE_CUBE_MAP_NEGATIVE_X │
├─────────────┼────────────────────────────────┤
│2 │ GL_TEXTURE_CUBE_MAP_POSITIVE_Y │
├─────────────┼────────────────────────────────┤
│3 │ GL_TEXTURE_CUBE_MAP_NEGATIVE_Y │
├─────────────┼────────────────────────────────┤
│4 │ GL_TEXTURE_CUBE_MAP_POSITIVE_Z │
├─────────────┼────────────────────────────────┤
│5 │ GL_TEXTURE_CUBE_MAP_NEGATIVE_Z │
└─────────────┴────────────────────────────────┘
For cube map array textures, zoffset is the first layer-face to access, and depth is the
number of layer-faces to access. A layer-face described by $k$ is translated into an array
layer and face according to $$ layer = \left\lfloor { layer \over 6 } \right\rfloor$$ and
$$ face = k \bmod 6. $$
Component groups from the specified sub-region are packed and placed into memory as
described for glGetTextureImage, starting with the texel at (xoffset, yoffset, zoffset).
ERRORS
GL_INVALID_VALUE error is generated if texture is not the name of an existing texture
object.
GL_INVALID_OPERATION error is generated if texture is the name of a buffer or multisample
texture.
GL_INVALID_VALUE is generated if xoffset, yoffset or zoffset are negative.
GL_INVALID_VALUE is generated if xoffset + width is greater than the texture's width,
yoffset + height is greater than the texture's height, or zoffset + depth is greater than
the texture's depth.
GL_INVALID_VALUE error is generated if the effective target is GL_TEXTURE_1D and either
yoffset is not zero, or height is not one.
GL_INVALID_VALUE error is generated if the effective target is GL_TEXTURE_1D,
GL_TEXTURE_1D_ARRAY, GL_TEXTURE_2D or GL_TEXTURE_RECTANGLE and either zoffset is not zero,
or depth is not one.
GL_INVALID_OPERATION error is generated if the buffer size required to store the requested
data is greater than bufSize.
VERSION SUPPORT
┌─────────────────────┬───────────────────────────────────────────────────────────────────────┐
│ │ OpenGL Version │
├─────────────────────┼─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┤
│Function │ 2.0 │ 2.1 │ 3.0 │ 3.1 │ 3.2 │ 3.3 │ 4.0 │ 4.1 │ 4.2 │ 4.3 │ 4.4 │ 4.5 │
│/ │ │ │ │ │ │ │ │ │ │ │ │ │
│Feature │ │ │ │ │ │ │ │ │ │ │ │ │
│Name │ │ │ │ │ │ │ │ │ │ │ │ │
├─────────────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
│glGetTextureSubImage │ - │ - │ - │ - │ - │ - │ - │ - │ - │ - │ - │ ✔ │
└─────────────────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┘
SEE ALSO
glGetTexImage(),
glGetTextureImage, glReadPixels(), glTexImage1D(), glTexImage2D(), glTexImage3D(),
glTexSubImage1D(), glTexSubImage2D(), glTexSubImage3D()
COPYRIGHT
Copyright © 2014 Khronos Group. This material may be distributed subject to the terms and
conditions set forth in the Open Publication License, v 1.0, 8 June 1999.
http://opencontent.org/openpub/.
COPYRIGHT
Copyright © 2014 Khronos Group
[FIXME: source] 01/03/2018 GLGETTEXTURESUBIMAGE(3G)