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, GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, or GL_TEXTURE_1D_ARRAY.

       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, cube-map texture
       image or a linear portion of a number of slices of a one-dimensional array texture 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.

       When target is GL_TEXTURE_1D_ARRAY then the y coordinate and height are treated as the start slice and
       number of slices to modify.

       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, or height, 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, GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, or GL_TEXTURE_1D_ARRAY.

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

ASSOCIATED GETS

       glGetTexImage()

SEE ALSO

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

COPYRIGHT

       Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2012-2013 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                                         10/22/2013                            GLCOPYTEXSUBIMAGE2D(3G)