glGetCompressedTextureSubImage — retrieve a sub-region of a compressed texture image from a compressed texture object
void glGetCompressedTextureSubImage(
|
GLuint texture, |
| GLint level, | |
| GLint xoffset, | |
| GLint yoffset, | |
| GLint zoffset, | |
| GLsizei width, | |
| GLsizei height, | |
| GLsizei depth, | |
| 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. Must be a
multiple of the compressed block's width, unless the
offset is zero and the size equals the texture
image size.
height
Specifies the height of the texture subimage. Must be a
multiple of the compressed block's height, unless the
offset is zero and the size equals the texture
image size.
depth
Specifies the depth of the texture subimage. Must be a
multiple of the compressed block's depth, unless the
offset is zero and the size equals the texture
image size.
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.
glGetCompressedTextureSubImage can be used to
obtain a sub-region of a compressed texture image instead of the whole
image, as long as the compressed data are arranged into fixed-size blocks
of texels. texture is the name of the texture
object, and must not be a buffer or multisample texture. The effective
target is the value of
GL_TEXTURE_TARGET for texture.
level and pixels have the
same meaning as the corresponding arguments of
glCompressedTexSubImage3D.
bufSize indicates the size of the buffer to receive
the retrieved pixel data.
For cube map textures, the behavior is as though
glGetCompressedTexImage were called once for each
requested face (selected by zoffset and
depth, as described below) with target
corresponding to the requested texture cube map face as indicated by the
table presented below. pixels is offset
appropriately for each successive image.
| 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
|
xoffset, yoffset and
zoffset indicate the position of the subregion to
return. width, height and
depth indicate the size of the region to return.
These arguments have the same meaning as for
glCompressedTexSubImage3D, though there are extra
restrictions, described in the errors section below.
The mapping between the xoffset,
yoffset, zoffset,
width, height and
depth parameters and the faces, layers, and
layer-faces for cube map, array, and cube map array textures is the same
as for glGetTextureSubImage.
The xoffset, yoffset,
zoffset offsets and width,
height and depth sizes must
be multiples of the values of
GL_PACK_COMPRESSED_BLOCK_WIDTH,
GL_PACK_COMPRESSED_BLOCK_HEIGHT, and
GL_PACK_COMPRESSED_BLOCK_DEPTH respectively, unless
offset is zero and the corresponding
size is the same as the texture size in that
dimension.
Pixel storage modes are treated as for
glGetCompressedTexSubImage. The texel at
(xoffset, yoffset,
zoffset) will be stored at the location indicated
by pixels and the current pixel packing parameters.
GL_INVALID_OPERATION error is generated if
texture is the name of a buffer or multisample
texture.
GL_INVALID_OPERATION error is generated if the
buffer size required to store the requested data is greater than
bufSize.
GL_INVALID_OPERATION error is generated if the
texture compression format is not based on fixed-size blocks.
GL_INVALID_VALUE error is generated if
texture is not the name of an existing texture
object.
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_VALUE error is generated if
xoffset, yoffset or
zoffset is not a multiple of the compressed block
width, height or depth respectively.
GL_INVALID_VALUE error is generated if
width, height or
depth is not a multiple of the compressed block
width, height or depth respectively, unless the
offset is zero and the size
equals the texture image size.
| 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 |
glGetCompressedTextureSubImage
|
- | - | - | - | - | - | - | - | - | - | - | ✔ |
glCompressedTexImage1D,
glCompressedTexImage2D,
glCompressedTexImage3D,
glCompressedTexSubImage1D,
glCompressedTexSubImage2D,
glCompressedTexSubImage3D,
glGetCompressedTexImage,
glGetCompressedTextureImage,
glReadPixels
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/.