glGetTextureSubImage — retrieve a sub-region of a texture image from a texture object
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); |
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.
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).
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.
| OpenGL Version | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Function / Feature Name | 2.0 | 2.1 | 3.0 | 3.1 | 3.2 | 3.3 | 4.0 | 4.1 | 4.2 | 4.3 | 4.4 | 4.5 |
glGetTextureSubImage
|
- | - | - | - | - | - | - | - | - | - | - | ✔ |
glGetTexImage,
glGetTextureImage,
glReadPixels,
glTexImage1D,
glTexImage2D,
glTexImage3D,
glTexSubImage1D,
glTexSubImage2D,
glTexSubImage3D
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/.