gl.CopyTexSubImage(level, x, y, xoffset, width[, yoffset, height])
gl.CopyTexSubImage()
replaces a rectangular portion of a one- or two-dimensional texture image
with pixels from the current #GL_READ_BUFFER
(rather than from main memory, as is the case for
gl.TexSubImage2D()). If the last two arguments are omitted, a rectangular
portion of a one-dimension texture image is replaced, otherwise a two-dimensional texture image
is the target.
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 gl.CopyPixels() 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.
Texturing has no effect in color index mode.
gl.PixelStore() and gl.PixelTransfer() modes affect texture images in exactly the way they affect gl.DrawPixels().
Please consult an OpenGL reference manual for more information.
#GL_INVALID_OPERATION
is generated if the texture array has not been defined by a previous gl.TexImage2D() or gl.CopyTexImage() operation.
#GL_INVALID_VALUE
is generated if level
is less than 0.
#GL_INVALID_VALUE
may be generated if level > log2(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.
#GL_INVALID_OPERATION
is generated if gl.CopyTexSubImage()
is executed between the execution of gl.Begin() and the corresponding execution of gl.End()
gl.IsEnabled() with argument #GL_TEXTURE_2D
or #GL_TEXTURE_1D