glGetCompressedTexImage — return a compressed texture image
void glGetCompressedTexImage(
|
GLenum target, |
GLint level, | |
void * pixels) ; |
void glGetnCompressedTexImage(
|
GLenum target, |
GLint level, | |
GLsizei bufSize, | |
void *pixels) ; |
void glGetCompressedTextureImage(
|
GLuint texture, |
GLint level, | |
GLsizei bufSize, | |
void *pixels) ; |
target
Specifies the target to which the texture is bound for
glGetCompressedTexImage
and
glGetnCompressedTexImage
functions.
GL_TEXTURE_1D
,
GL_TEXTURE_1D_ARRAY
,
GL_TEXTURE_2D
,
GL_TEXTURE_2D_ARRAY
,
GL_TEXTURE_3D
,
GL_TEXTURE_CUBE_MAP_ARRAY
,
GL_TEXTURE_CUBE_MAP_POSITIVE_X
,
GL_TEXTURE_CUBE_MAP_NEGATIVE_X
,
GL_TEXTURE_CUBE_MAP_POSITIVE_Y
,
GL_TEXTURE_CUBE_MAP_NEGATIVE_Y
,
GL_TEXTURE_CUBE_MAP_POSITIVE_Z
, and
GL_TEXTURE_CUBE_MAP_NEGATIVE_Z
,
GL_TEXTURE_RECTANGLE
are accepted.
texture
Specifies the texture object name for
glGetCompressedTextureImage
function.
level
Specifies the level-of-detail number of the desired image. Level 0 is the base image level. Level $n$ is the $n$-th mipmap reduction image.
bufSize
Specifies the size of the buffer pixels
for glGetCompressedTextureImage
and
glGetnCompressedTexImage
functions.
pixels
Returns the compressed texture image.
glGetCompressedTexImage
and
glGetnCompressedTexImage
return the compressed
texture image associated with target
and
lod
into pixels
.
glGetCompressedTextureImage
serves the same purpose,
but instead of taking a texture target, it takes the ID of the texture
object. pixels
should be an array of
bufSize
bytes for
glGetnCompresedTexImage
and
glGetCompressedTextureImage
functions, and of
GL_TEXTURE_COMPRESSED_IMAGE_SIZE
bytes in case of
glGetCompressedTexImage
. If the actual data takes
less space than bufSize
, the remaining bytes will
not be touched. target
specifies the texture
target, to which the texture the data the function should extract the data
from is bound to. lod
specifies the level-of-detail
number of the desired image.
If a non-zero named buffer object is bound to the
GL_PIXEL_PACK_BUFFER
target (see
glBindBuffer) while a texture image is requested,
pixels
is treated as a byte offset into the buffer
object's data store.
To minimize errors, first verify that the texture is compressed by
calling glGetTexLevelParameter with argument
GL_TEXTURE_COMPRESSED
. If the texture is compressed,
you can determine the amount of memory required to store the compressed
texture by calling glGetTexLevelParameter with argument
GL_TEXTURE_COMPRESSED_IMAGE_SIZE
. Finally, retrieve
the internal format of the texture by calling glGetTexLevelParameter with argument
GL_TEXTURE_INTERNAL_FORMAT
. To store the texture for
later use, associate the internal format and size with the retrieved
texture image. These data can be used by the respective texture or
subtexture loading routine used for loading target
textures.
GL_INVALID_OPERATION
is generated by
glGetCompressedTextureImage
if
texture
is not the name of an existing texture
object.
GL_INVALID_VALUE
is generated if
level
is less than zero or greater than the maximum
number of LODs permitted by the implementation.
GL_INVALID_OPERATION
is generated if
glGetCompressedTexImage
,
glGetnCompressedTexImage
, and
glGetCompressedTextureImage
is used to retrieve a
texture that is in an uncompressed internal format.
GL_INVALID_OPERATION
is generated if a non-zero
buffer object name is bound to the
GL_PIXEL_PACK_BUFFER
target, the buffer storage was
not initialized with glBufferStorage
using
GL_MAP_PERSISTENT_BIT
flag, and the buffer object's
data store is currently mapped.
GL_INVALID_OPERATION
is generated if a non-zero
buffer object name is bound to the
GL_PIXEL_PACK_BUFFER
target and the data would be
packed to the buffer object such that the memory writes required would
exceed the data store size.
glGetTexLevelParameter with argument
GL_TEXTURE_COMPRESSED
glGetTexLevelParameter with argument
GL_TEXTURE_COMPRESSED_IMAGE_SIZE
glGetTexLevelParameter with argument
GL_TEXTURE_INTERNAL_FORMAT
glGet with argument
GL_PIXEL_PACK_BUFFER_BINDING
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 |
glGetCompressedTexImage
|
✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
glGetCompressedTextureImage
|
- | - | - | - | - | - | - | - | - | - | - | ✔ |
glGetnCompressedTexImage
|
- | - | - | - | - | - | - | - | - | - | - | ✔ |
glActiveTexture, glCompressedTexImage1D, glCompressedTexImage2D, glCompressedTexImage3D, glCompressedTexSubImage1D, glCompressedTexSubImage2D, glCompressedTexSubImage3D, glReadPixels, glTexImage1D, glTexImage2D, glTexImage3D, glTexParameter, glTexSubImage1D, glTexSubImage2D, glTexSubImage3D
Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010-2014 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see https://opencontent.org/openpub/.