glCompressedTexSubImage2D, glCompressedTextureSubImage2D - specify a two-dimensional texture subimage in

glGetCompressedTexImage()

       glGet() with argument GL_TEXTURE_COMPRESSEDglGet() with argument GL_PIXEL_UNPACK_BUFFER_BINDINGglGetTexLevelParameter() with arguments GL_TEXTURE_INTERNAL_FORMAT and GL_TEXTURE_COMPRESSED_IMAGE_SIZE

voidglCompressedTexSubImage2D(GLenumtarget,GLintlevel,GLintxoffset,GLintyoffset,GLsizeiwidth,GLsizeiheight,GLenumformat,GLsizeiimageSize,constGLvoid*data);voidglCompressedTextureSubImage2D(GLuinttexture,GLintlevel,GLintxoffset,GLintyoffset,GLsizeiwidth,GLsizeiheight,GLenumformat,GLsizeiimageSize,constvoid*data);

       Copyright © 1991-2006 Silicon Graphics, Inc.
       Copyright © 2010-2014 Khronos Group

[FIXME: source]                                    11/18/2024                           GLCOMPRESSEDTEXSUBIM(3G)

       Texturing allows elements of an image array to be read by shaders.

       glCompressedTexSubImage2D and glCompressedTextureSubImage2D redefine a contiguous subregion of an
       existing two-dimensional texture image. The texels referenced by data replace the portion of the existing
       texture array with x indices xoffset and xoffset + width - 1, and the y indices yoffset and yoffset +
       height - 1, inclusive. This region may not include any texels outside the range of the texture array as
       it was originally specified. It is not an error to specify a subtexture with width of 0, but such a
       specification has no effect.

       internalformat must be a known compressed image format (such as GL_RGTC) or an extension-specified
       compressed-texture format. The format of the compressed texture image is selected by the GL
       implementation that compressed it (see glTexImage2D()) and should be queried at the time the texture was
       compressed with glGetTexLevelParameter().

       If a non-zero named buffer object is bound to the GL_PIXEL_UNPACK_BUFFER target (see glBindBuffer())
       while a texture image is specified, data is treated as a byte offset into the buffer object's data store.

GL_INVALID_ENUM is generated if internalformat is of the generic compressed internal formats:
       GL_COMPRESSED_RED, GL_COMPRESSED_RG, GL_COMPRESSED_RGB, GL_COMPRESSED_RGBA.  GL_COMPRESSED_SRGB, or
       GL_COMPRESSED_SRGB_ALPHA.

       GL_INVALID_ENUM is generated by glCompressedTexSubImage2D if target is GL_TEXTURE_RECTANGLE or
       GL_PROXY_TEXTURE_RECTANGLE.

       GL_INVALID_VALUE is generated if imageSize is not consistent with the format, dimensions, and contents of
       the specified compressed image data.

       GL_INVALID_OPERATION is generated if parameter combinations are not supported by the specific compressed
       internal format as specified in the specific texture compression extension.

       GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the GL_PIXEL_UNPACK_BUFFER
       target 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_UNPACK_BUFFER
       target and the data would be unpacked from the buffer object such that the memory reads required would
       exceed the data store size.

       GL_INVALID_OPERATION is generated by glCompressedTextureSubImage2D if texture is not the name of an
       existing texture object.

       GL_INVALID_OPERATION is generated by glCompressedTextureSubImage2D if the effective target is
       GL_TEXTURE_RECTANGLE.

       Undefined results, including abnormal program termination, are generated if data is not encoded in a
       manner consistent with the extension specification defining the internal compression format.

       glCompressedTexSubImage2D, glCompressedTextureSubImage2D - specify a two-dimensional texture subimage in
       a compressed format

target
           Specifies the target to which the texture is bound for glCompressedTexSubImage2D function. Must be
           GL_TEXTURE_1D_ARRAY, GL_TEXTURE_2D, 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, or
           GL_TEXTURE_CUBE_MAP_NEGATIVE_Z.

       texture
           Specifies the texture object name for glCompressedTextureSubImage2D function.

       level
           Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth 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.

       width
           Specifies the width of the texture subimage.

       height
           Specifies the height of the texture subimage.

       format
           Specifies the format of the compressed image data stored at address data.

       imageSize
           Specifies the number of unsigned bytes of image data starting at the address specified by data.

       data
           Specifies a pointer to the compressed image data in memory.

glActiveTexture(), glCompressedTexImage1D(), glCompressedTexImage2D(), glCompressedTexImage3D(),
       glCompressedTexSubImage1D(), glCompressedTexSubImage3D(), glCopyTexImage1D(), glCopyTexImage2D(),
       glCopyTexSubImage1D(), glCopyTexSubImage2D(), glCopyTexSubImage3D(), glPixelStore(), glTexImage2D(),
       glTexImage3D(), glTexSubImage1D(), glTexSubImage2D(), glTexSubImage3D(), glTexParameter()

       ┌───────────────────────────────┬───────────────────────────────────────────────────────────────────────┐
       │                               │                OpenGLVersion                                         │
       ├───────────────────────────────┼─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┤
       │ 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                          │     │     │     │     │     │     │     │     │     │     │     │     │
       ├───────────────────────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
       │ glCompressedTexSubImage2D     │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │
       ├───────────────────────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
       │ glCompressedTextureSubImage2D │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  ✔  │
       └───────────────────────────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┘