1991-2006
Silicon Graphics, Inc.
glCopyTexSubImage2D
3G

# 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 of the active texture unit. 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

Texturing maps a portion of a specified texture image onto each graphical primitive for which texturing is active. Texturing is active when the current fragment shader or vertex shader makes use of built-in texture lookup functions.

`glCopyTexSubImage2D` replaces a rectangular portion of a two-dimensional texture image or cube-map texture image with pixels from the current framebuffer (rather than from client 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 with `format` set to `GL_RGBA`, but the process stops just after conversion of RGBA values. Subsequent processing is identical to that described for glTexSubImage2D, beginning with the clamping of the R, G, B, and A values to the range 0 1 and then conversion 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 are outside the framebuffer 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

`glCopyTexSubImage2D` specifies the two-dimensional or cube-map texture for the current texture unit, specified with glActiveTexture.

## 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_VALUE` is generated if `level` is less than 0.

`GL_INVALID_VALUE` may be generated if level > log 2 &af; 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 > 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 glTexImage2D or glCopyTexImage2D operation.

`GL_INVALID_OPERATION` is generated if the currently bound framebuffer's format does not contain a superset of the components required by the texture's base internal format.

`GL_INVALID_FRAMEBUFFER_OPERATION` is generated if the currently bound framebuffer is not framebuffer complete (i.e. the return value from glCheckFramebufferStatus is not `GL_FRAMEBUFFER_COMPLETE`).

## Associated Gets

glGet with argument `GL_MAX_TEXTURE_SIZE` or `GL_MAX_CUBE_MAP_TEXTURE_SIZE`

## See Also

glActiveTexture, glCheckFramebufferStatus, glCopyTexImage2D, glTexImage2D, glTexParameter, glTexSubImage2D

## Copyright

Copyright 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/.