glCompressedTexImage2D man page on Oracle
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GLCOMPRESSEDTEXIMAGE(3G) OpenGL Manual GLCOMPRESSEDTEXIMAGE(3G)
NAME
glCompressedTexImage2D - specify a two-dimensional texture image in a
compressed format
C SPECIFICATION
void glCompressedTexImage2D(GLenum target, GLint level,
GLenum internalformat, GLsizei width,
GLsizei height, GLint border,
GLsizei imageSize, const GLvoid * data);
PARAMETERS
target
Specifies the target texture. Must be GL_TEXTURE_2D,
GL_PROXY_TEXTURE_2D, GL_TEXTURE_1D_ARRAY,
GL_PROXY_TEXTURE_1D_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,
GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, or GL_PROXY_TEXTURE_CUBE_MAP.
level
Specifies the level-of-detail number. Level 0 is the base image
level. Level n is the nth mipmap reduction image.
internalformat
Specifies the format of the compressed image data stored at address
data.
width
Specifies the width of the texture image. All implementations
support 2D texture and cube map texture images that are at least
16384 texels wide.
height
Specifies the height of the texture image. All implementations
support 2D texture and cube map texture images that are at least
16384 texels high.
border
This value must be 0.
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.
DESCRIPTION
Texturing allows elements of an image array to be read by shaders.
glCompressedTexImage2D loads a previously defined, and retrieved,
compressed two-dimensional texture image if target is GL_TEXTURE_2D, or
one of the cube map faces such as GL_TEXTURE_CUBE_MAP_POSITIVE_X. (see
glTexImage2D()).
If target is GL_TEXTURE_1D_ARRAY, data is treated as an array of
compressed 1D textures.
If target is GL_PROXY_TEXTURE_2D, GL_PROXY_TEXTURE_1D_ARRAY or
GL_PROXY_CUBE_MAP, no data is read from data, but all of the texture
image state is recalculated, checked for consistency, and checked
against the implementation's capabilities. If the implementation cannot
handle a texture of the requested texture size, it sets all of the
image state to 0, but does not generate an error (see glGetError()). To
query for an entire mipmap array, use an image array level greater than
or equal to 1.
internalformat must be a known compressed image format (such as
GL_RGTC) or an extension-specified compressed-texture format. When a
texture is loaded with glTexImage2D() using a generic compressed
texture format (e.g., GL_COMPRESSED_RGB), the GL selects from one of
its extensions supporting compressed textures. In order to load the
compressed texture image using glCompressedTexImage2D, query the
compressed texture image's size and format using
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.
If the compressed data are arranged into fixed-size blocks of texels,
the pixel storage modes can be used to select a sub-rectangle from a
larger containing rectangle. These pixel storage modes operate in the
same way as they do for glTexImage2D(). In the following description,
denote by bs, bw, bh, and bd, the values of pixel storage modes
GL_UNPACK_COMPRESSED_BLOCK_SIZE, GL_UNPACK_COMPRESSED_BLOCK_WIDTH,
GL_UNPACK_COMPRESSED_BLOCK_HEIGHT, and
GL_UNPACK_COMPRESSED_BLOCK_DEPTH, respectively. bs is the compressed
block size in bytes; bw, bh, and bd are the compressed block width,
height, and depth in pixels.
By default the pixel storage modes GL_UNPACK_ROW_LENGTH,
GL_UNPACK_SKIP_ROWS, GL_UNPACK_SKIP_PIXELS, GL_UNPACK_IMAGE_HEIGHT and
GL_UNPACK_SKIP_IMAGES are ignored for compressed images. To enable
GL_UNPACK_SKIP_PIXELS and GL_UNPACK_ROW_LENGTH, bs and bw must both be
non-zero. To also enable GL_UNPACK_SKIP_ROWS and
GL_UNPACK_IMAGE_HEIGHT, bh must be non-zero. To also enable
GL_UNPACK_SKIP_IMAGES, bd must be non-zero. All parameters must be
consistent with the compressed format to produce the desired results.
When selecting a sub-rectangle from a compressed image:
· the value of GL_UNPACK_SKIP_PIXELS must be a multiple of bw;.RE
· the value of GL_UNPACK_SKIP_ROWS must be a multiple of bw..RE
imageSize must be equal to:
b s × width b w × height b h
NOTES
The specific compressed internal formats GL_COMPRESSED_RGB8_ETC2,
GL_COMPRESSED_SRGB8_ETC2, GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2,
GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2,
GL_COMPRESSED_RGBA8_ETC2_EAC, GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC,
GL_COMPRESSED_R11_EAC, GL_COMPRESSED_SIGNED_R11_EAC,
GL_COMPRESSED_RG11_EAC, and GL_COMPRESSED_SIGNED_RG11_EAC are available
only if the GL version is 4.3 or higher.
ERRORS
GL_INVALID_ENUM is generated if internalformat is not one of the
specific compressed internal formats: GL_COMPRESSED_RED_RGTC1,
GL_COMPRESSED_SIGNED_RED_RGTC1, GL_COMPRESSED_RG_RGTC2,
GL_COMPRESSED_SIGNED_RG_RGTC2. GL_COMPRESSED_RGBA_BPTC_UNORM,
GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM,
GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT,
GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT, GL_COMPRESSED_RGB8_ETC2,
GL_COMPRESSED_SRGB8_ETC2, GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2,
GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2,
GL_COMPRESSED_RGBA8_ETC2_EAC, GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC,
GL_COMPRESSED_R11_EAC, GL_COMPRESSED_SIGNED_R11_EAC,
GL_COMPRESSED_RG11_EAC, or GL_COMPRESSED_SIGNED_RG11_EAC.
GL_INVALID_VALUE is generated if imageSize is not consistent with the
format, dimensions, and contents of the specified compressed image
data.
GL_INVALID_VALUE is generated if border is not 0.
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.
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.
ASSOCIATED GETS
glGetCompressedTexImage()
glGet() with argument GL_TEXTURE_COMPRESSED
glGet() with argument GL_PIXEL_UNPACK_BUFFER_BINDING
glGetTexLevelParameter() with arguments GL_TEXTURE_INTERNAL_FORMAT and
GL_TEXTURE_COMPRESSED_IMAGE_SIZE
SEE ALSO
glActiveTexture(), glCompressedTexImage1D(), glCompressedTexImage3D(),
glCompressedTexSubImage1D(), glCompressedTexSubImage2D(),
glCompressedTexSubImage3D(), glCopyTexImage1D(), glCopyTexSubImage1D(),
glCopyTexSubImage2D(), glCopyTexSubImage3D(), glPixelStore(),
glTexImage2D(), glTexImage3D(), glTexSubImage1D(), glTexSubImage2D(),
glTexSubImage3D(), glTexParameter()
COPYRIGHT
Copyright © 1991-2006 Silicon Graphics, Inc. © 2011 Khronos Group.
This document is licensed under the SGI Free Software B License. For
details, see http://oss.sgi.com/projects/FreeB/.
AUTHORS
opengl.org
opengl.org 04/29/2014 GLCOMPRESSEDTEXIMAGE(3G)
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