glGetTexParameter(3G) OpenGL Reference glGetTexParameter(3G)
NAME
glGetTexParameterfv, glGetTexParameteriv - return texture parameter
values
C SPECIFICATION
void glGetTexParameterfv( GLenum target,
GLenum pname,
GLfloat *params )
void glGetTexParameteriv( GLenum target,
GLenum pname,
GLint *params )
PARAMETERS
target Specifies the symbolic name of the target texture.
GLTEXTURE1D, GLTEXTURE2D, GLDETAILTEXTURE2DSGIS, and
GLTEXTURE3DEXT are accepted.
pname Specifies the symbolic name of a texture parameter.
GLTEXTUREBORDERCOLOR, GLTEXTUREMAGFILTER,
GLTEXTUREMINFILTER, GLTEXTUREWRAPS, GLTEXTUREWRAPT,
GLTEXTUREWRAPREXT, GLDETAILTEXTURELEVELSGIS,
GLDETAILTEXTUREMODESGIS, GLDETAILTEXTUREFUNCPOINTSSGIS,
GLSHARPENTEXTUREFUNCPOINTSSGIS,
GLPOSTTEXTUREFILTERBIASSGIX,
GLPOSTTEXTUREFILTERSCALESGIX, GLTEXTUREPRIORITY,
GLTEXTUREPRIORITYEXT, GLTEXTURERESIDENT,
GLTEXTURERESIDENTEXT, GLTEXTUREMINLODSGIS,
GLTEXTUREMAXLODSGIS, GLTEXTUREBASELEVELSGIS,
GLTEXTUREMAXLEVELSGIS, GLDUALTEXTURESELECTSGIS,
GLQUADTEXTURESELECTSGIS, GLTEXTUREFILTER4SIZESGIS,
GLTEXTURECLIPMAPFRAMESGIX, GLTEXTURECLIPMAPCENTERSGIX,
GLTEXTURECLIPMAPOFFSETSGIX,
GLTEXTURECLIPMAPVIRTUALDEPTHSGIX, GLTEXTURECOMPARESGIX,
GLTEXTURECOMPAREOPERATORSGIX, and GLSHADOWAMBIENTSGIX are
accepted.
params Returns the texture parameters.
DESCRIPTION
glGetTexParameter returns in params the value or values of the texture
parameter specified as pname. target defines the target texture
(GLTEXTURE1D, GLTEXTURE2D, GLDETAILTEXTURE2DSGIS, or
GLTEXTURE3DEXT). pname accepts the same symbols as glTexParameter,
with the same interpretations, plus a few additional symbols.
GLTEXTUREMAGFILTER Returns the single-valued texture magnification
filter, a symbolic constant.
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glGetTexParameter(3G) OpenGL Reference glGetTexParameter(3G)
GLTEXTUREMINFILTER Returns the single-valued texture minification
filter, a symbolic constant.
GLTEXTUREWRAPS Returns the single-valued wrapping function for
texture coordinate s, a symbolic constant.
GLTEXTUREWRAPT Returns the single-valued wrapping function for
texture coordinate t, a symbolic constant.
GLTEXTUREWRAPREXT Returns the single-valued wrapping function for
texture coordinate r, a symbolic constant.
GLTEXTUREBORDERCOLOR Returns four integer or floating-point numbers
that comprise the RGBA color of the texture
border. Floating-point values are returned in
the range [0,1]. Integer values are returned as
a linear mapping of the internal floating-point
representation such that 1.0 maps to the most
positive representable integer and -1.0 maps to
the most negative representable integer.
GLDETAILTEXTURELEVELSGIS
Returns an integer specifying the number of
levels that separate the level zero image of
GLTEXTURE2D and the image of
GLDETAILTEXTURE2DSGIS. See
glDetailTexFuncSGIS for more information.
GLDETAILTEXTUREMODESGIS
Returns a single enumerated value describing the
detail texture mode. See glDetailTexFuncSGIS.
GLDETAILTEXTUREFUNCPOINTSSGIS
Returns the number of points in the
specification of the detail texture scaling
function. See glGetDetailTexFuncSGIS.
GLSHARPENTEXTUREFUNCPOINTSSGIS
Returns the number of points in the
specification of the sharpen texture scaling
function. See glGetSharpenTexFuncSGIS.
GLPOSTTEXTUREFILTERBIASSGIX
Returns four floating-point numbers that
comprise the R, G, B and A bias factors for the
texture. See glTexParameterfv and
glTexParameteriv.
GLPOSTTEXTUREFILTERSCALESGIX
Returns four floating-point numbers that
comprise the R, G, B and A scale factors for the
texture. See glTexParameterfv and
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glGetTexParameter(3G) OpenGL Reference glGetTexParameter(3G)
glTexParameteriv.
GLTEXTUREPRIORITY Returns the residence priority of the target
texture (or the named texture bound to it). See
glPrioritizeTextures.
GLTEXTUREPRIORITYEXT Returns the residence priority of the target
texture (or the named texture bound to it). See
glPrioritizeTexturesEXT.
GLTEXTURERESIDENT Returns the residence status of the target
texture. If the value returned in params is
GLTRUE, the texture is resident in texture
memory. See glAreTexturesResident.
GLTEXTURERESIDENTEXT Returns the residence status of the target
texture. If the value returned in params is
GLTRUE, the texture is resident in texture
memory. See glAreTexturesResidentEXT.
GLTEXTUREMINLODSGIS Returns the low end of the LOD clamping range.
GLTEXTUREMAXLODSGIS Returns the high end of the LOD clamping range.
GLTEXTUREBASELEVELSGIS
Returns the base level of the mipmap set
associated with target.
GLTEXTUREMAXLEVELSGIS
Returns the maximum level of the mipmap set
associated with target.
GLDUALTEXTURESELECTSGIS
Returns the currently selected component group
for GLDUAL textures. Its value is 0 or 1.
See glTexParameter, glTexImage1D, glTexImage2D
and glTexImage3DEXT.
GLQUADTEXTURESELECTSGIS,
Returns the currently selected component group
for GLQUAD textures. Its value is 0, 1, 2 or
3. See glTexParameter, glTexImage1D,
glTexImage2D and glTexImage3DEXT.
GLTEXTUREFILTER4SIZESGIS
Returns the implementation-dependent texture
filtering constant Size used by the
SGIStexturefilter4 extension. For an
explanation of this constant, see
glTexFilterFuncSGIS.
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glGetTexParameter(3G) OpenGL Reference glGetTexParameter(3G)
GLTEXTURECLIPMAPFRAMESGIX
Returns the size of the texture memory area
reserved for paging new texels into a clipmap.
The size is expressed as a (floating-point)
fraction of half the width of a clipped level.
See glTexParameter for more information.
GLTEXTURECLIPMAPCENTERSGIX
Returns the s and t coordinates of the center of
a clipmap's region of interest. See
glTexParameter for more information.
GLTEXTURECLIPMAPOFFSETSGIX
Returns the s and t toroidal offsets for a
clipmap. See glTexParameter for more
information.
GLTEXTURECLIPMAPVIRTUALDEPTHSGIX
Returns the lod offset, depth, and virtual
depth, respectively, for a clipmap. See
glTexParameter for more information.
GLTEXTURECOMPARESGIX Returns a single Boolean value indicating
whether the texture comparison operation is
enabled. See glTexParameter for more
information.
GLTEXTURECOMPAREOPERATORSGIX
Returns the current texture comparison operator.
See glTexParameter for more information.
GLSHADOWAMBIENTSGIX Returns the current ambient lighting coefficient
for shadows. See glTexParameter for more
information.
NOTES
GLTEXTUREPRIORITY and GLTEXTURERESIDENT are only available if the GL
version is 1.1 or greater.
If an error is generated, no change is made to the contents of params.
GLTEXTUREWRAPREXT is part of the EXTtexture3D extension.
GLDETAILTEXTURELEVELSGIS, GLDETAILTEXTUREMODESGIS, and
GLDETAILTEXTUREFUNCPOINTSSGIS are part of the SGISdetailtexture
extension. GLSHARPENTEXTUREFUNCPOINTSSGIS is part of the
SGISsharpentexture extension. GLPOSTTEXTUREFILTERBIASSGIX and
GLPOSTTEXTUREFILTERSCALESGIX are part of the SGIXtexturescalebias
extension. GLTEXTUREPRIORITYEXT and GLTEXTURERESIDENTEXT are part
of the EXTtextureobject extension. GLTEXTUREMINLODSGIS
GLTEXTUREMAXLODSGIS, GLTEXTUREBASELEVELSGIS, and
GLTEXTUREMAXLEVELSGIS are part of the SGIStexturelod extension.
GLDUALTEXTURESELECTSGIS and GLQUADTEXTURESELECTSGIS are part of
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glGetTexParameter(3G) OpenGL Reference glGetTexParameter(3G)
the SGIStextureselect extension. GLTEXTUREFILTER4SIZESGIS is part
of the SGIStexturefilter4 extension. GLTEXTURECLIPMAPFRAMESGIX,
GLTEXTURECLIPMAPCENTERSGIX, GLTEXTURECLIPMAPOFFSETSGIX, and
GLTEXTURECLIPMAPVIRTUALDEPTHSGIX are part of the SGIXclipmap
extension. GLTEXTURECOMPARESGIX and GLTEXTURECOMPAREOPERATORSGIX
are part of the SGIXshadow extension. GLSHADOWAMBIENTSGIX is part of
the SGIXshadowambient extension. See glIntro for more information on
using extensions.
ERRORS
GLINVALIDENUM is generated if target or pname is not an accepted value.
GLINVALIDENUM is generated if pname is GLTEXTUREFILTER4SIZESGIS and
target is not GLTEXTURE1D or GLTEXTURE2D.
GLINVALIDOPERATION is generated if glGetTexParameter is executed
between the execution of glBegin and the corresponding execution of
glEnd.
MACHINE DEPENDENCIES
The SGIXclipmap extension is supported only on InfiniteReality systems.
The following restrictions apply:
1. For best performance, the ``breakpoint'' clipmap level (B) must
be loaded before any other level. The implementation derives
the size of the clipmap from the size of this level, so loading
this level first permits efficient allocation of texture memory.
2. Clipmaps must be square.
3. GLTEXTUREWRAPS and GLTEXTUREWRAPT must be set to
GLCLAMPTOEDGESGIS.
4. It is more efficient to set clipmap attributes that affect
texture memory allocation (such as
GLTEXTURECLIPMAPFRAMESGIX) before loading the first level of
the clipmap, rather than after loading it.
5. Virtual clipmaps (whose GLTEXTURECLIPMAPVIRTUALDEPTHSGIX
parameters have been defined) use texture memory inefficiently.
Each level of detail allocates a region of texture memory the
same size as that of a clipped level. Any clipmap whose depth
is less than GLMAXCLIPMAPDEPTHSGIX should avoid this by not
specifying GLTEXTURECLIPMAPVIRTUALDEPTHSGIX parameters. An
application can not readback the texture levels whose size is
smaller than that of the clipped level.
6. The depth of the virtual clipmap given in
GLTEXTURECLIPMAPVIRTUALDEPTHSGIX must be defined before any
texture levels are downloaded, and it can not be changed once it
has been specified. If the application tries to change the
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glGetTexParameter(3G) OpenGL Reference glGetTexParameter(3G)
virtual depth, no action is taken.
7. Subloading texture into a portion of level B+1 of a virtual
clipmap (the first level coarser than the breakpoint) is
undefined; however, the entire level can be subloaded.
8. When using virtual clipmaps, an application should not
overcommit texture memory. Doing so will result in undefined
behavior.
RealityEngine, RealityEngine2, and VTX systems do not support
GLDETAILTEXTURELEVELSGIS correctly.
On InfiniteReality systems, if the post-texture filter scale and bias
values are set to values other than the defaults, they are limited to the
range [0.0, 1.0). (note: this range excludes 1.0.) The
SGIXtexturescalebias extension is not supported on RealityEngine,
RealityEngine2, and VTX systems or on High Impact and Maximum Impact
systems.
The SGIStextureselect extension is supported only on InfiniteReality
systems, High Impact and Maximum Impact on Octane systems, and High
Impact and Maximum Impact on Indigo2 systems with the TRAM option card.
The SGIStexturefilter4 extension is supported only on InfiniteReality
systems.
On InfiniteReality systems, GLINVALIDVALUE is generated if the value of
the argument n to the command glTexFilterFuncSGIS does not equal the
value of the implementation dependent constant Size, which can be
determined by calling glGetTexParameter with argument
GLTEXTUREFILTER4SIZESGIS. This restriction will be removed in a
future release.
SEE ALSO
glAreTexturesResident, glPrioritizeTextures, glTexParameter
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