183 lines
5.7 KiB
Plaintext
183 lines
5.7 KiB
Plaintext
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'\" e
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'\"! eqn | mmdoc
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'\"macro stdmacro
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.ds Vn Version 1.2
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.ds Dt 24 September 1999
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.ds Re Release 1.2.1
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.ds Dp Jan 14 18:30
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.ds Dm 01 gettexlev
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.ds Xs 50913 7 gettexlevelparameter.gl
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.TH GLGETTEXLEVELPARAMETER 3G
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.SH NAME
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.B "glGetTexLevelParameterfv, glGetTexLevelParameteriv
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\- return texture parameter values for a specific level of detail
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.SH C SPECIFICATION
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void \f3glGetTexLevelParameterfv\fP(
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GLenum \fItarget\fP,
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.nf
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.ta \w'\f3void \fPglGetTexLevelParameterfv( 'u
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GLint \fIlevel\fP,
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GLenum \fIpname\fP,
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GLfloat \fI*params\fP )
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.fi
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void \f3glGetTexLevelParameteriv\fP(
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GLenum \fItarget\fP,
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.nf
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.ta \w'\f3void \fPglGetTexLevelParameteriv( 'u
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GLint \fIlevel\fP,
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GLenum \fIpname\fP,
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GLint \fI*params\fP )
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.fi
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.EQ
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delim $$
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.EN
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.SH PARAMETERS
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.TP \w'\f2target\fP\ \ 'u
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\f2target\fP
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Specifies the symbolic name of the target texture,
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either \%\f3GL_TEXTURE_1D\fP, \%\f3GL_TEXTURE_2D\fP, \%\f3GL_TEXTURE_3D\fP,
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\%\f3GL_PROXY_TEXTURE_1D\fP, \%\f3GL_PROXY_TEXTURE_2D\fP, or
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\%\f3GL_PROXY_TEXTURE_3D\fP.
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.TP
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\f2level\fP
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Specifies the level-of-detail number of the desired image.
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Level 0 is the base image level.
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Level $n$ is the $n$th mipmap reduction image.
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.TP
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\f2pname\fP
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Specifies the symbolic name of a texture parameter.
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\%\f3GL_TEXTURE_WIDTH\fP,
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\%\f3GL_TEXTURE_HEIGHT\fP,
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\%\f3GL_TEXTURE_DEPTH\fP,
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\%\f3GL_TEXTURE_INTERNAL_FORMAT\fP,
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\%\f3GL_TEXTURE_BORDER\fP,
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\%\f3GL_TEXTURE_RED_SIZE\fP,
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\%\f3GL_TEXTURE_GREEN_SIZE\fP,
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\%\f3GL_TEXTURE_BLUE_SIZE\fP,
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\%\f3GL_TEXTURE_ALPHA_SIZE\fP,
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\%\f3GL_TEXTURE_LUMINANCE_SIZE\fP, and
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\%\f3GL_TEXTURE_INTENSITY_SIZE\fP are accepted.
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.TP
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\f2params\fP
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Returns the requested data.
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.SH DESCRIPTION
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\%\f3glGetTexLevelParameter\fP returns in \f2params\fP texture parameter values for a specific
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level-of-detail value,
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specified as \f2level\fP.
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\f2target\fP defines the target texture,
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either \%\f3GL_TEXTURE_1D\fP, \%\f3GL_TEXTURE_2D\fP, \%\f3GL_TEXTURE_3D\fP,
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\%\f3GL_PROXY_TEXTURE_1D\fP,
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\%\f3GL_PROXY_TEXTURE_2D\fP, or
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\%\f3GL_PROXY_TEXTURE_3D\fP.
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.BR
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.P
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\%\f3GL_MAX_TEXTURE_SIZE\fP, and \%\f3GL_MAX_3D_TEXTURE_SIZE\fP are not really
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descriptive enough.
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It has to report the largest square texture image that can be
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accommodated with mipmaps and borders,
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but a long skinny texture, or a texture without mipmaps and borders, may
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easily fit in texture memory.
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The proxy targets allow the user to more accurately query
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whether the GL can accommodate a texture of a given configuration.
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If the texture cannot be accommodated, the texture state variables, which
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may be queried with \%\f3glGetTexLevelParameter\fP, are set to 0. If the texture can be accommodated,
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the texture state values will be set as they would be set for a
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non-proxy target.
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.P
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\f2pname\fP specifies the texture parameter whose value or values
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will be returned.
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.P
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The accepted parameter names are as follows:
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.TP 10
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\%\f3GL_TEXTURE_WIDTH\fP
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\f2params\fP returns a single value,
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the width of the texture image.
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This value includes the border of the texture image. The initial value is
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0.
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.TP
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\%\f3GL_TEXTURE_HEIGHT\fP
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\f2params\fP returns a single value,
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the height of the texture image.
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This value includes the border of the texture image. The initial value is
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0.
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.TP
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\%\f3GL_TEXTURE_DEPTH\fP
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\f2params\fP returns a single value,
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the depth of the texture image.
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This value includes the border of the texture image. The initial value is
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0.
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.TP
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\%\f3GL_TEXTURE_INTERNAL_FORMAT\fP
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\f2params\fP returns a single value,
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the internal of the texture image.
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.TP
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\%\f3GL_TEXTURE_BORDER\fP
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\f2params\fP returns a single value,
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the width in pixels of the border of the texture image. The initial value
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is 0.
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.TP
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\%\f3GL_TEXTURE_RED_SIZE\fP,
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.TP
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\%\f3GL_TEXTURE_GREEN_SIZE\fP,
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.TP
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\%\f3GL_TEXTURE_BLUE_SIZE\fP,
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.TP
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\%\f3GL_TEXTURE_ALPHA_SIZE\fP,
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.TP
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\%\f3GL_TEXTURE_LUMINANCE_SIZE\fP,
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.TP
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\%\f3GL_TEXTURE_INTENSITY_SIZE\fP
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The internal storage resolution of an individual component.
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The resolution chosen by the GL will be a close match for the resolution
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requested by the user with the component argument of \%\f3glTexImage1D\fP,
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\%\f3glTexImage2D\fP, \%\f3glTexImage3D\fP, \%\f3glCopyTexImage1D\fP, and
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\%\f3glCopyTexImage2D\fP. The initial value is 0.
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.SH NOTES
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If an error is generated,
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no change is made to the contents of \f2params\fP.
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.P
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\%\f3GL_TEXTURE_INTERNAL_FORMAT\fP is available only if the GL version is
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1.1 or greater. In version 1.0, use \%\f3GL_TEXTURE_COMPONENTS\fP
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instead.
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.P
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\%\f3GL_PROXY_TEXTURE_1D\fP and \%\f3GL_PROXY_TEXTURE_2D\fP are
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available only if the GL version is 1.1 or greater.
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.P
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\%\f3GL_TEXTURE_3D\fP, \%\f3GL_PROXY_TEXTURE_3D\fP, and \%\f3GL_TEXTURE_DEPTH\fP
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are available only if the GL version is 1.2 or greater.
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.P
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When the \%\f3GL_ARB_multitexture\fP extension is supported, \%\f3glGetTexLevelParameter\fP returns
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the texture level parameters for the active texture unit.
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.SH ERRORS
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\%\f3GL_INVALID_ENUM\fP is generated if \f2target\fP or \f2pname\fP is not an
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accepted value.
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.P
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\%\f3GL_INVALID_VALUE\fP is generated if \f2level\fP is less than 0.
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.P
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\%\f3GL_INVALID_VALUE\fP may be generated if \f2level\fP is greater
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than $ log sub 2$ \f2max\fP,
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where \f2max\fP is the returned value of \%\f3GL_MAX_TEXTURE_SIZE\fP.
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.P
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\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glGetTexLevelParameter\fP
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is executed between the execution of \%\f3glBegin\fP
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and the corresponding execution of \%\f3glEnd\fP.
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.SH SEE ALSO
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\%\f3glActiveTextureARB(3G)\fP,
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\%\f3glGetTexParameter(3G)\fP,
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\%\f3glCopyTexImage1D(3G)\fP,
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\%\f3glCopyTexImage2D(3G)\fP,
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\%\f3glCopyTexSubImage1D(3G)\fP,
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\%\f3glCopyTexSubImage2D(3G)\fP,
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\%\f3glCopyTexSubImage3D(3G)\fP,
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\%\f3glTexEnv(3G)\fP,
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\%\f3glTexGen(3G)\fP,
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\%\f3glTexImage1D(3G)\fP,
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\%\f3glTexImage2D(3G)\fP,
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\%\f3glTexImage3D(3G)\fP,
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\%\f3glTexSubImage1D(3G)\fP,
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\%\f3glTexSubImage2D(3G)\fP,
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\%\f3glTexSubImage3D(3G)\fP,
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\%\f3glTexParameter(3G)\fP
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