glGetTextureSubImage(3G)
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 $$
face = k mod 6. $$
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] 07/22/2015 GLGETTEXTURESUBIMAGE(3G)
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