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 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 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/.