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glCopyTexSubImage2D - copy a two-dimensional texture subimage
GLsizei height );
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.
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
glCopyTexSubImage2D() is available only if the GL version is 1.1 or
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.
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 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
glIsEnabled() with argument GL_TEXTURE_2D
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)
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