NAME    [Toc]    [Back]

       glCopyTexSubImage2D   -  copy  a  two-dimensional  texture
       subimage

SYNOPSIS    [Toc]    [Back]

       void glCopyTexSubImage2D(
               GLenum target,
               GLint level,
               GLint xoffset,
               GLint yoffset,
               GLint x,
               GLint y,
               GLsizei width,
               GLsizei height );

PARAMETERS    [Toc]    [Back]

       Specifies  the  target  texture.  Must  be  GL_TEXTURE_2D.
       Specifies  the level-of-detail number. Level 0 is the base
       image level. Level n is the nth  mipmap  reduction  image.
       Specifies  a  texel  offset  in the x direction within the
       texture array.  Specifies a texel offset in the  y  direction
 within the texture array.  Specify the window coordinates
 of the lower left corner of the  rectangular  region
       of  pixels  to be copied.  Specifies the width of the texture
 subimage.  Specifies the height of the texture subimage.

DESCRIPTION    [Toc]    [Back]

       glCopyTexSubImage2D()  replaces a rectangular portion of a
       two-dimensional texture image with pixels from the current
       GL_READ_BUFFER  (rather  than  from main memory, as is the
       case for glTexSubImage2D()).

       The screen-aligned pixel rectangle with lower left  corner
       at  (x, y) and with width width and height height replaces
       the portion of the texture array with  x  indices  xoffset
       through  xoffset+width-1, inclusive, and y indices yoffset
       through yoffset+height-1, inclusive, at the  mipmap  level
       specified by level.

       The  pixels  in  the rectangle are processed exactly as if
       glCopyPixels() had been called, but the process stops just
       before  final conversion.  At this point, all pixel component
 values are clamped to the range [0, 1] and then  converted
 to the texture's internal  for storage in the texel
       array.

       The destination rectangle in the  texture  array  may  not
       include  any  texels  outside  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.

       If any of the pixels within the specified rectangle of the
       current GL_READ_BUFFER are outside the read window associated
 with the current rendering context, then  the  values
       obtained for those pixels are undefined.

       No change is made to the internalformat, width, height, or
       border parameters of the specified  texture  array  or  to
       texel values outside the specified subregion.

NOTES    [Toc]    [Back]

       glCopyTexSubImage2D()  is available only if the GL version
       is 1.1 or greater.

       Texturing has no effect in color index mode.

       glPixelStore() and glPixelTransfer() modes affect  texture
       images in exactly the way they affect glDrawPixels().

       When  the  GL_ARB_imaging extension is supported, the RGBA
       components read from the framebuffer may be  processed  by
       the  imaging  pipeline.   See  glTexImage1D() for specific
       details.

ERRORS    [Toc]    [Back]

       GL_INVALID_ENUM is generated  if  target  is  not  GL_TEXTURE_2D.


       GL_INVALID_OPERATION is generated if the texture array has
       not been defined by a previous glTexImage2D()  or  glCopyTexImage2D()
 operation.

       GL_INVALID_VALUE is generated if level is less than 0.

       GL_INVALID_VALUE may be generated if level is greater than
       log[2] max, where max is the returned value of GL_MAX_TEXTURE_SIZE.


       GL_INVALID_VALUE  is  generated  if  x  < -b or if y < -b,
       where b is the border width of the texture array.

       GL_INVALID_VALUE is generated  if  xoffset  <  -b,  (xoffset+width)>(w
  -b),  yoffset<  -b,  or (yoffset+height)>(h
       -b), where w is the GL_TEXTURE_WIDTH,  h  is  the  GL_TEXTURE_HEIGHT,
 and b is the GL_TEXTURE_BORDER of the texture
       image being modified. Note that w and h include twice  the
       border width.

       GL_INVALID_OPERATION is generated if glCopyTexSubImage2D()
       is executed between the execution  of  glBegin()  and  the
       corresponding execution of glEnd().

ASSOCIATED GETS    [Toc]    [Back]

       glGetTexImage()
       glIsEnabled() with argument GL_TEXTURE_2D

SEE ALSO    [Toc]    [Back]

       glCopyPixels(3), glCopyTexImage1D(3), glCopyTexImage2D(3),
       glCopyTexSubImage1D(3),  glCopyTexSubImage3D(3),  glPixelStore(3),   glPixelTransfer(3),   glReadBuffer(3),  glTexEnv(3),  glTexGen(3),  glTexImage1D(3),   glTexImage2D(3),
       glTexImage3D(3),   glTexParameter(3),  glTexSubImage1D(3),
       glTexSubImage2D(3), glTexSubImage3D(3)



                                          glCopyTexSubImage2D(3G)