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GLCOPYTEXSUBIMAGE2D(3G)                          OpenGL 3.3                          GLCOPYTEXSUBIMAGE2D(3G)



NAME
       glCopyTexSubImage2D - copy a two-dimensional texture subimage

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


PARAMETERS
       target
           Specifies the target texture. Must be 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.

       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.

       x, y
           Specify the window coordinates of the lower left corner of the rectangular region of pixels to be
           copied.

       width
           Specifies the width of the texture subimage.

       height
           Specifies the height of the texture subimage.

DESCRIPTION
       glCopyTexSubImage2D replaces a rectangular portion of a two-dimensional texture image or cube-map
       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 glReadPixels() 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 format 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
       glPixelStore() modes affect texture images.

ERRORS
       GL_INVALID_ENUM is generated if target is not 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.


       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 > log 2 ^, max, where max is the returned value of
       GL_MAX_TEXTURE_SIZE.


       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.

ASSOCIATED GETS
       glGetTexImage()

SEE ALSO
       glCopyTexImage1D(), glCopyTexImage2D(), glCopyTexSubImage1D(), glCopyTexSubImage3D(), glPixelStore(),
       glReadBuffer(), glTexImage1D(), glTexImage2D(), glTexImage3D(), glTexParameter(), glTexSubImage1D(),
       glTexSubImage2D(), glTexSubImage3D()


COPYRIGHT
       Copyright (C) 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software
       B License. For details, see http://oss.sgi.com/projects/FreeB/.



OpenGL 3.3                                       03/08/2011                          GLCOPYTEXSUBIMAGE2D(3G)