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GL_EXT_copy_texture
EXT_copy_texture
Name Strings
GL_EXT_copy_texture
Version
$Date: 1995/06/17 03:33:42 $ $Revision: 1.21 $
Number
10
Dependencies
EXT_texture is required.
EXT_texture3D affects the definition of this extension.
SGIS_texture_filter4 affects the definition of this extension.
EXT_subtexture affects the definition of this extension.
Overview
This extension defines methods to load texture images directly from the
framebuffer. Methods are defined for both complete and partial
replacement of a texture image. Because it is not possible to define
an entire 3D texture using a 2D framebuffer image, 3D textures are
supported only for partial replacement.
void CopyTexImage1DEXT(enum target,
int level,
enum internalformat,
int x,
int y,
sizei width,
int border);
void CopyTexImage2DEXT(enum target,
int level,
enum internalformat,
int x,
int y,
sizei width,
sizei height,
int border);
void CopyTexSubImage1DEXT(enum target,
int level,
int xoffset,
int x,
int y,
sizei width);
void CopyTexSubImage2DEXT(enum target,
int level,
int xoffset,
int yoffset,
int x,
int y,
sizei width,
sizei height);
void CopyTexSubImage3DEXT(enum target,
int level,
int xoffset,
int yoffset,
int zoffset,
int x,
int y,
sizei width,
sizei height);
None
Additions to Chapter 2 of the 1.0 Specification (OpenGL Operation)
None
Additions to Chapter 3 of the 1.0 Specification (Rasterization)
CopyTexImage1DEXT and CopyTexImage2DEXT are related to TexImage1D and
TexImage2D in exactly the way that CopyPixels is related to DrawPixels.
Rather than accepting image data from memory, they copy image data from
the color buffer specified by the current ReadBuffer mode.
CopyTexImage2DEXT accepts image data from a width+2*border pixel wide by
height+2*border pixel high color buffer region whose lower-left pixel
has window coordinates <x>,<y>. If any pixels within this region are
outside the window that is associated with the GL context, the values
obtained for those pixels are undefined. These pixel values are
processed exactly as if CopyPixels had been called, but the process
stops just before final conversion. Subsequent processing is exactly
as though TexImage2D had be called, beginning with the clamping of the
pixel group components to [0,1]. Pixel ordering is such that lower X
screen coordinates correspond to lower i texture coordinates, and lower
Y screen coordinates correspond to lower j texture coordinates (refer to
Figure 3.10 - A texture image and the coordinates used to access it, GL
Specification). The semantics and accepted values of the <target>,
<level>, and <border> parameters are exactly equivalent to their
TexImage2D counterparts, except that <target> does not accept
PROXY_TEXTURE_2D_EXT. The semantics of <internalformat> are identical
to those of the <components> parameter of TexImage2D, except that
values 1, 2, 3, and 4 are not accepted by CopyTexImage2DEXT.
CopyTexImage1DEXT accepts image data from a width+2*border pixel wide
by 1 pixel high color buffer region whose left-most pixel has window
coordinates <x>,<y>. If any pixels within this region are outside the
window that is associated with the GL context, the values obtained for
those pixels are undefined. The pixels are processed just as those of
CopyTexImage2DEXT are, and they define a texture such that lower X
window coordinates correspond to lower i texture coordinates, as per
Figure 3.10 of the GL Specification. The semantics and accepted values
of the <level>, <border>, and <internalformat> parameters are exactly
those of CopyTexImage2DEXT. <target> accepts only TEXTURE_1D.
If EXT_subtexture is supported, this extension also defines
CopyTexSubImage1DEXT and CopyTexSubImage2DEXT. These commands are
related to TexSubImage1DEXT and TexSubImage2DEXT in exactly the way
that CopyPixels is related to DrawPixels. Rather than accepting image
data from memory, they copy image data from the framebuffer. The
semantics and accepted values of the <target>, <level>, <xoffset>, and
<yoffset> parameters are exactly equivalent to their TexSubImage1DEXT
and TexSubImage2DEXT counterparts. The semantics and accepted values
of the <x>, <y>, <width>, and <height> parameters are exactly equivalent
to their CopyTexImage1DEXT and CopyTexImage2DEXT counterparts.
If EXT_subtexture and EXT_texture3D are both supported, this extension
also defines CopyTexSubImage3DEXT. Because framebuffer memory is two-
dimensional, only a portion of a single s,t slice of a 3D texture is
replaced by this command. Thus CopyTexSubImage3DEXT is related to
TexSubImage3DEXT in exactly the way that CopyPixels is related to
DrawPixels, except that it is as though TexSubImage3DEXT parameter
<depth> were 1. Rather than accepting image data from memory,
CopyTexSubImage3DEXT copies image data from the framebuffer. The
semantics and accepted values of the <target>, <level>, <xoffset>,
<yoffset>, and <zoffset> parameters are exactly equivalent to their
TexSubImage3DEXT counterparts. The semantics and accepted values of
the <x>, <y>, <width>, and <height> parameters are exactly equivalent
to their CopyTexImage2DEXT counterparts.
Additions to Chapter 4 of the 1.0 Specification (Per-Fragment Operations
and the Framebuffer)
None
Additions to Chapter 5 of the 1.0 Specification (Special Functions)
None
Additions to Chapter 6 of the 1.0 Specification (State and State Requests)
None
Additions to the GLX Specification
None
GLX Protocol
Five new GL rendering commands are added. The following commands are sent to the
server as part of a glXRender request:
CopyTexImage1DEXT
2 32 rendering command length
2 4119 rendering command opcode
4 ENUM target
4 INT32 level
4 ENUM internalformat
4 INT32 x
4 INT32 y
4 INT32 width
4 INT32 border
CopyTexImage2DEXT
2 36 rendering command length
2 4120 rendering command opcode
4 ENUM target
4 INT32 level
4 ENUM internalformat
4 INT32 x
4 INT32 y
4 INT32 width
4 INT32 height
4 INT32 border
CopyTexSubImage1DEXT
2 28 rendering command length
2 4121 rendering command opcode
4 ENUM target
4 INT32 level
4 INT32 xoffset
4 INT32 x
4 INT32 y
4 INT32 width
CopyTexSubImage2DEXT
2 36 rendering command length
2 4122 rendering command opcode
4 ENUM target
4 INT32 level
4 INT32 xoffset
4 INT32 yoffset
4 INT32 x
4 INT32 y
4 INT32 width
4 INT32 height
CopyTexSubImage3DEXT
2 40 rendering command length
2 4123 rendering command opcode
4 ENUM target
4 INT32 level
4 INT32 xoffset
4 INT32 yoffset
4 INT32 zoffset
4 INT32 x
4 INT32 y
4 INT32 width
4 INT32 height
Dependencies on EXT_texture
EXT_texture is required. This extension builds on the notion of
internal image format, which is defined by EXT_texture.
Dependencies on EXT_texture3D
If EXT_texture3D is not supported, CopyTexSubImage3DEXT is not defined
by this extension.
Dependencies on SGIS_texture_filter4
If SGIS_texture_filter4 is not supported, 2 is not accepted as a border
value.
Dependencies on EXT_subtexture
If EXT_subtexture is not supported, CopyTexSubImage1DEXT,
CopyTexSubImage2DEXT, and CopyTexSubImage3DEXT are not defined by this
extension.
Errors
INVALID_ENUM is generated if CopyTexImage1DEXT or CopyTexSubImage1DEXT
parameter <target> is not TEXTURE_1D. (The commands defined by this
extension do not accept PROXY targets.)
INVALID_ENUM is generated if CopyTexImage2DEXT or CopyTexSubImage2DEXT
parameter <target> is not TEXTURE_2D.
INVALID_ENUM is generated if CopyTexSubImage3DEXT parameter <target>
is not TEXTURE_3D_EXT.
INVALID_VALUE is generated if CopyTexImage1DEXT or CopyTexImage2DEXT
parameter <level> is less than zero, or greater than the maximum value
supported by the implementation.
INVALID_ENUM is generated if CopyTexImage1DEXT or CopyTexImage2DEXT
parameter <internalformat> is not ALPHA, RGB, RGBA, LUMINANCE,
LUMINANCE_ALPHA, or one of the token values defined by EXT_texture.
INVALID_VALUE is generated when any of the <width> or <height>
parameters of CopyTexImage1DEXT or CopyTexImage2DEXT is less than zero,
or if it cannot be represented as 2**k + 2*border for some integer k.
INVALID_VALUE is generated if CopyTexSubImage1DEXT, CopyTexSubImage2DEXT,
or CopyTexSubImage3DEXT parameter <xoffset>, CopyTexSubImage2DEXT or
CopyTexSubImage3DEXT parameter <yoffset>, or CopyTexSubImage3DEXT
parameter <zoffset> is less than -TEXTURE_BORDER, where TEXTURE_BORDER
is the border width of the texture array to be modified.
INVALID_VALUE is generated if CopyTexSubImage1DEXT, CopyTexSubImage2DEXT,
or CopyTexSubImage3DEXT (xoffset + width) > (TEXTURE_WIDTH -
TEXTURE_BORDER), or if CopyTexSubImage2DEXT or CopyTexSubImage3DEXT
(yoffset + height) > (TEXTURE_HEIGHT - TEXTURE_BORDER), or if
CopyTexSubImage3DEXT zoffset >= (TEXTURE_DEPTH_EXT - TEXTURE_BORDER).
Note that TEXTURE_WIDTH, TEXTURE_HEIGHT, and TEXTURE_DEPTH_EXT include
twice the border width.
TEXTURE_TOO_LARGE_EXT is generated by CopyTexImage1DEXT or
CopyTexImage2DEXT if the specified image is too large, for any reason.
(See EXT_texture for a discussion of how applications can query the
maximum texture size.)
INVALID_VALUE is generated if CopyTexImage1DEXT or CopyTexImage2DEXT
parameter <border> is not 0, 1, or 2.
INVALID_OPERATION is generated if CopyTexImage1DEXT, CopyTexImage2DEXT,
CopyTexSubImage1DEXT, CopyTexSubImage2DEXT, or CopyTexSubImage3DEXT is
called between execution of Begin and the corresponding execution of
End.
New State
None
New Implementation Dependent State
None
Implementation Support
List of OpenGL implementations supporting the GL_EXT_copy_texture extension
Original File
Original text file for the GL_EXT_copy_texture extension
Page generated on Sun Nov 20 18:37:24 2005