NAME¶
glCompressedTexImage1D - specify a one-dimensional texture image in a compressed
format
C SPECIFICATION¶
void
glCompressedTexImage1D(GLenum target,
GLint level, GLenum internalformat,
GLsizei width, GLint border,
GLsizei imageSize,
const GLvoid * data);
PARAMETERS¶
target
Specifies the target texture. Must be
GL_TEXTURE_1D or GL_PROXY_TEXTURE_1D.
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 texture images that are at least 64 texels wide. The
height of the 1D texture image is 1.
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.
glCompressedTexImage1D loads a previously defined, and retrieved,
compressed one-dimensional texture image if
target is
GL_TEXTURE_1D (see
glTexImage1D()).
If
target is
GL_PROXY_TEXTURE_1D, 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 an extension-specified compressed-texture format.
When a texture is loaded with
glTexImage1D() 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
glCompressedTexImage1D, 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
glTexImage1D(). 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
imageSize must be equal to:
b s × width b w
ERRORS¶
GL_INVALID_ENUM is generated if
internalformat is not a supported
specific compressed internal formats, or is one 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_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_NUM_COMPRESSED_TEXTURE_FORMATS
glGet() with argument
GL_COMPRESSED_TEXTURE_FORMATS
glGet() with argument
GL_PIXEL_UNPACK_BUFFER_BINDING
glGetTexLevelParameter() with arguments
GL_TEXTURE_INTERNAL_FORMAT
and
GL_TEXTURE_COMPRESSED_IMAGE_SIZE
SEE ALSO¶
glActiveTexture(),
glCompressedTexImage2D(),
glCompressedTexImage3D(),
glCompressedTexSubImage1D(),
glCompressedTexSubImage2D(),
glCompressedTexSubImage3D(),
glCopyTexImage1D(),
glCopyTexImage2D(),
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/.