glCopyTexImage2D(3G) OpenGL Reference glCopyTexImage2D(3G)
NAME
glCopyTexImage2D - copy pixels into a 2D texture image
C SPECIFICATION
void glCopyTexImage2D( GLenum target,
GLint level,
GLenum internalformat,
GLint x,
GLint y,
GLsizei width,
GLsizei height,
GLint border )
PARAMETERS
target Specifies the target texture. Must be GLTEXTURE2D.
level Specifies the level-of-detail number. Level 0 is the
base image level. Level n is the nth mipmap reduction
image.
internalformat Specifies the internal format of the texture. Must be
one of the following symbolic constants: GLALPHA,
GLALPHA4, GLALPHA8, GLALPHA12, GLALPHA16,
GLLUMINANCE, GLLUMINANCE4, GLLUMINANCE8,
GLLUMINANCE12, GLLUMINANCE16, GLLUMINANCEALPHA,
GLLUMINANCE4ALPHA4, GLLUMINANCE6ALPHA2,
GLLUMINANCE8ALPHA8, GLLUMINANCE12ALPHA4,
GLLUMINANCE12ALPHA12, GLLUMINANCE16ALPHA16,
GLINTENSITY, GLINTENSITY4, GLINTENSITY8,
GLINTENSITY12, GLINTENSITY16, GLRGB, GLR3G3B2,
GLRGB4, GLRGB5, GLRGB8, GLRGB10, GLRGB12, GLRGB16,
GLRGBA, GLRGBA2, GLRGBA4, GLRGB5A1, GLRGBA8,
GLRGB10A2, GLRGBA12, or GLRGBA16.
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 image. Must be 0 or
2**n + 2*border for some integer n.
height Specifies the height of the texture image. Must be 0 or
2**m + 2*border for some integer m.
border Specifies the width of the border. Must be either 0 or
1.
DESCRIPTION
glCopyTexImage2D defines a two-dimensional texture image with pixels from
the current GLREADBUFFER.
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glCopyTexImage2D(3G) OpenGL Reference glCopyTexImage2D(3G)
The screen-aligned pixel rectangle with lower left corner at (x, y) and
with a width of width + 2 * border and a height of height + 2 * border
defines the texture array at the mipmap level specified by level.
internalformat specifies the internal format of the texture array.
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 format for storage in the texel
array.
Pixel ordering is such that lower x and y screen coordinates correspond
to lower s and t texture coordinates.
If any of the pixels within the specified rectangle of the current
GLREADBUFFER are outside the window associated with the current
rendering context, then the values obtained for those pixels are
undefined.
NOTES
glCopyTexImage2D is available only if the GL version is 1.1 or greater.
Texturing has no effect in color index mode.
1, 2, 3, and 4 are not accepted values for internalformat.
An image with height or width of 0 indicates a NULL texture.
ERRORS
GLINVALIDENUM is generated if target is not GLTEXTURE2D.
GLINVALIDVALUE is generated if level is less than 0.
GLINVALIDVALUE may be generated if level is greater than log max, where
2
max is the returned value of GLMAXTEXTURESIZE.
GLINVALIDVALUE is generated if width or height is less than 0, greater
than 2 + GLMAXTEXTURESIZE, or if width or height cannot be represented
as 2**k + 2 * border for some integer k.
GLINVALIDVALUE is generated if border is not 0 or 1.
GLINVALIDVALUE is generated if internalformat is not one of the
allowable values.
GLINVALIDOPERATION is generated if glCopyTexImage2D is executed between
the execution of glBegin and the corresponding execution of glEnd.
ASSOCIATED GETS
glGetTexImage
glIsEnabled with argument GLTEXTURE2D
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glCopyTexImage2D(3G) OpenGL Reference glCopyTexImage2D(3G)
MACHINE DEPENDENCIES
RealityEngine, RealityEngine2, and VTX systems do not support color
matrix transformations on images as they are loaded to or read back from
texture memory.
RealityEngine, RealityEngine2, and VTX systems support glCopyTexImage2D
and glCopyTexImage2DEXT with the following restrictions:
1. Only level 0 is supported; other levels result in a
GLINVALIDVALUE error.
2. glCopyTexImage2D and glCopyTexImage2DEXT cannot be used if a GLX
video source is the current read drawable (see
glXMakeCurrentReadSGI). Executing it will generate a
GLINVALIDOPERATION error.
3. GLINTERLACESGIX is not supported (see glEnable).
4. Borders are not supported; hence the width of the border should
be 0.
On InfiniteReality systems, there is a performance benefit when the width
of the image to be transferred to texture memory is a multiple of 8.
Texture borders are not supported on InfiniteReality systems.
Applications should use borderless textures and GLCLAMPTOEDGESGIS
wrap mode.
The SGIXinterlace extension is supported only on InfiniteReality
systems, on RealityEngine, RealityEngine2, and VTX systems, and on O2
systems.
On High Impact and Maximum Impact systems the number of bits per
component, represented internally, is the same for all components and
will be 4, 8, or 12 bits per component. All specified internal formats
will receive an equal or greater representation in this scheme, up to the
12-bit limit. High Impact and Maximum Impact on Indigo2 systems do not
support texture internal formats of the type GLINTENSITY or GLALPHA,
although High Impact and Maximum Impact on Octane systems do support
these types.
High Impact and Maximum Impact on Indigo2 systems without the TRAM option
card support 4 bits per component for GLRGB and GLRGBA, 4/8 bits per
component for GLLUMINANCEALPHA, and 4/8/12 bits per component for
GLLUMINANCE.
SEE ALSO
glCopyPixels, glCopyTexImage1D, glCopyTexSubImage1D, glCopyTexSubImage2D,
glPixelStore, glPixelTransfer, glTexEnv, glTexGen, glTexImage1D,
glTexImage2D, glTexSubImage1D, glTexSubImage2D, glTexParameter
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glCopyTexImage2D(3G) OpenGL Reference glCopyTexImage2D(3G)
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