Name

glCompressedTexSubImage2D — specify a two-dimensional compressed texture subimage

C Specification

void glCompressedTexSubImage2D(GLenum target,
 GLint level,
 GLint xoffset,
 GLint yoffset,
 GLsizei width,
 GLsizei height,
 GLenum format,
 GLsizei imageSize,
 const GLvoid * data);
 

Parameters

target

Specifies the target texture. Must be GL_TEXTURE_2D.

level

Specifies the level-of-detail number.

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 pixel data. Currently, there is no supported format.

imageSize

Specifies the size of the compressed pixel data in bytes.

data

Specifies a pointer to the compressed image data in memory.

Description

glCompressedTexSubImage2D redefines a contiguous subregion of an existing two-dimensional compressed texture image. The texels referenced by pixels replace the portion of the existing texture array with x indices xoffset and xoffset+width-1 , inclusive, and 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 zero width or height, but such a specification has no effect.

format must be the same compressed-texture format previously specified by glCompressedTexImage2D.

The required paletted formats do not allow subimage updates, but other formats defined by extensions may.

Notes

glPixelStorei has no effect on compressed texture images.

glCompressedTexSubImage2D specifies the two-dimensional sub texture for the currently bound texture, specified with glBindTexture, and the current texture unit, specified with glActiveTexture.

Errors

GL_INVALID_ENUM is generated if target is not GL_TEXTURE_2D.

GL_INVALID_VALUE is generated if level is less than 0.

GL_INVALID_VALUE may be generated if level is greater than log2max , where max is the returned value of GL_MAX_TEXTURE_SIZE.

GL_INVALID_VALUE is generated if xoffset < 0 , xoffset + width > w , yoffset < 0 , or yoffset + height > h , where w is the width and h is the height of the texture image being modified.

GL_INVALID_VALUE is generated if width or height is less than 0.

GL_INVALID_OPERATION is generated if the texture array has not been defined by a previous glCompressedTexImage2D operation whose internalformat matches the format of glCompressedTexSubImage2D.

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.

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

glGet with arguments GL_NUM_COMPRESSED_TEXTURE_FORMATS and GL_COMPRESSED_TEXTURE_FORMATS

glGet with argument GL_MAX_TEXTURE_SIZE

See Also

glActiveTexture, glBindTexture, glCompressedTexImage2D, glCopyTexSubImage2D, glGet, glPixelStorei, glTexEnv, glTexParameter

Copyright

Copyright © 2003-2004 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.