glgettexparameter - Man Page
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.
GL_TEXTURE_1D, GL_TEXTURE_2D, GL_DETAIL_TEXTURE_2D_SGIS, and
GL_TEXTURE_3D_EXT are accepted.
pname Specifies the symbolic name of a texture parameter.
GL_TEXTURE_BORDER_COLOR, GL_TEXTURE_MAG_FILTER,
GL_TEXTURE_MIN_FILTER, GL_TEXTURE_WRAP_S, GL_TEXTURE_WRAP_T,
GL_TEXTURE_WRAP_R_EXT, GL_DETAIL_TEXTURE_LEVEL_SGIS,
GL_DETAIL_TEXTURE_MODE_SGIS, GL_DETAIL_TEXTURE_FUNC_POINTS_SGIS,
GL_SHARPEN_TEXTURE_FUNC_POINTS_SGIS,
GL_POST_TEXTURE_FILTER_BIAS_SGIX,
GL_POST_TEXTURE_FILTER_SCALE_SGIX, GL_TEXTURE_PRIORITY_EXT,
GL_TEXTURE_RESIDENT_EXT, GL_TEXTURE_MIN_LOD_SGIS,
GL_TEXTURE_MAX_LOD_SGIS, GL_TEXTURE_BASE_LEVEL_SGIS,
GL_TEXTURE_MAX_LEVEL_SGIS, GL_DUAL_TEXTURE_SELECT_SGIS,
GL_QUAD_TEXTURE_SELECT_SGIS, GL_TEXTURE_FILTER4_SIZE_SGIS,
GL_TEXTURE_CLIPMAP_FRAME_SGIX, GL_TEXTURE_CLIPMAP_CENTER_SGIX,
GL_TEXTURE_CLIPMAP_OFFSET_SGIX, GL_TEXTURE_COMPARE_SGIX,
GL_TEXTURE_COMPARE_OPERATOR_SGIX, and GL_SHADOW_AMBIENT_SGIX 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
(GL_TEXTURE_1D, GL_TEXTURE_2D, GL_DETAIL_TEXTURE_2D_SGIS, or
GL_TEXTURE_3D_EXT). pname accepts the same symbols as glTexParameter,
with the same interpretations, plus a few additional symbols.
GL_TEXTURE_MAG_FILTER Returns the single-valued texture magnification
filter, a symbolic constant.
GL_TEXTURE_MIN_FILTER Returns the single-valued texture minification
filter, a symbolic constant.
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glGetTexParameter(3G) OpenGL Reference glGetTexParameter(3G)
GL_TEXTURE_WRAP_S Returns the single-valued wrapping function for
texture coordinate s, a symbolic constant.
GL_TEXTURE_WRAP_T Returns the single-valued wrapping function for
texture coordinate t, a symbolic constant.
GL_TEXTURE_WRAP_R_EXT Returns the single-valued wrapping function for
texture coordinate r, a symbolic constant.
GL_TEXTURE_BORDER_COLOR 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.
GL_DETAIL_TEXTURE_LEVEL_SGIS
Returns an integer specifying the number of
levels that separate the level zero image of
GL_TEXTURE_2D and the image of
GL_DETAIL_TEXTURE_2D_SGIS. See
glDetailTexFuncSGIS for more information.
GL_DETAIL_TEXTURE_MODE_SGIS
Returns a single enumerated value describing the
detail texture mode. See glDetailTexFuncSGIS.
GL_DETAIL_TEXTURE_FUNC_POINTS_SGIS
Returns the number of points in the
specification of the detail texture scaling
function. See glGetDetailTexFuncSGIS.
GL_SHARPEN_TEXTURE_FUNC_POINTS_SGIS
Returns the number of points in the
specification of the sharpen texture scaling
function. See glGetSharpenTexFuncSGIS.
GL_POST_TEXTURE_FILTER_BIAS_SGIX
Returns four floating-point numbers that
comprise the R, G, B and A bias factors for the
texture. See glTexParameterfv and
glTexParameteriv.
GL_POST_TEXTURE_FILTER_SCALE_SGIX
Returns four floating-point numbers that
comprise the R, G, B and A scale factors for the
texture. See glTexParameterfv and
glTexParameteriv.
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glGetTexParameter(3G) OpenGL Reference glGetTexParameter(3G)
GL_TEXTURE_PRIORITY_EXT Returns the residence priority of the target
texture (or the named texture bound to it). See
glPrioritizeTexturesEXT.
GL_TEXTURE_RESIDENT_EXT Returns the residence status of the target
texture. If the value returned in params is
GL_TRUE, the texture is resident in texture
memory. See glAreTexturesResidentEXT.
GL_TEXTURE_MIN_LOD_SGIS Returns the low end of the LOD clamping range.
GL_TEXTURE_MAX_LOD_SGIS Returns the high end of the LOD clamping range.
GL_TEXTURE_BASE_LEVEL_SGIS
Returns the base level of the mipmap set
associated with target.
GL_TEXTURE_MAX_LEVEL_SGIS
Returns the maximum level of the mipmap set
associated with target.
GL_DUAL_TEXTURE_SELECT_SGIS
Returns the currently selected component group
for GL_DUAL_ textures. Its value is 0 or 1.
See glTexParameter, glTexImage1D, glTexImage2D
and glTexImage3DEXT.
GL_QUAD_TEXTURE_SELECT_SGIS,
Returns the currently selected component group
for GL_QUAD_ textures. Its value is 0, 1, 2 or
3. See glTexParameter, glTexImage1D,
glTexImage2D and glTexImage3DEXT.
GL_TEXTURE_FILTER4_SIZE_SGIS
Returns the implementation-dependent texture
filtering constant Size used by the
SGIS_texture_filter4 extension. For an
explanation of this constant, see
glTexFilterFuncSGIS.
GL_TEXTURE_CLIPMAP_FRAME_SGIX
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.
GL_TEXTURE_CLIPMAP_CENTER_SGIX
Returns the s and t coordinates of the center of
a clipmap's region of interest. See
glTexParameter for more information.
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glGetTexParameter(3G) OpenGL Reference glGetTexParameter(3G)
GL_TEXTURE_CLIPMAP_OFFSET_SGIX
Returns the s and t toroidal offsets for a
clipmap. See glTexParameter for more
information.
GL_TEXTURE_COMPARE_SGIX Returns a single Boolean value indicating
whether the texture comparison operation is
enabled. See glTexParameter for more
information.
GL_TEXTURE_COMPARE_OPERATOR_SGIX
Returns the current texture comparison operator.
See glTexParameter for more information.
GL_SHADOW_AMBIENT_SGIX Returns the current ambient lighting coefficient
for shadows. See glTexParameter for more
information.
NOTES
If an error is generated, no change is made to the contents of params.
GL_TEXTURE_WRAP_R_EXT is part of the EXT_texture3D extension.
GL_DETAIL_TEXTURE_LEVEL_SGIS, GL_DETAIL_TEXTURE_MODE_SGIS, and
GL_DETAIL_TEXTURE_FUNC_POINTS_SGIS are part of the SGIS_detail_texture
extension. GL_SHARPEN_TEXTURE_FUNC_POINTS_SGIS is part of the
SGIS_sharpen_texture extension. GL_POST_TEXTURE_FILTER_BIAS_SGIX and
GL_POST_TEXTURE_FILTER_SCALE_SGIX are part of the SGIX_texture_scale_bias
extension. GL_TEXTURE_PRIORITY_EXT and GL_TEXTURE_RESIDENT_EXT are part
of the EXT_texture_object extension. GL_TEXTURE_MIN_LOD_SGIS
GL_TEXTURE_MAX_LOD_SGIS, GL_TEXTURE_BASE_LEVEL_SGIS, and
GL_TEXTURE_MAX_LEVEL_SGIS are part of the SGIS_texture_lod extension.
GL_DUAL_TEXTURE_SELECT_SGIS and GL_QUAD_TEXTURE_SELECT_SGIS are part of
the SGIS_texture_select extension. GL_TEXTURE_FILTER4_SIZE_SGIS is part
of the SGIS_texture_filter4 extension. GL_TEXTURE_CLIPMAP_FRAME_SGIX,
GL_TEXTURE_CLIPMAP_CENTER_SGIX, and GL_TEXTURE_CLIPMAP_OFFSET_SGIX are
part of the SGIX_clipmap extension. GL_TEXTURE_COMPARE_SGIX and
GL_TEXTURE_COMPARE_OPERATOR_SGIX are part of the SGIX_shadow extension.
GL_SHADOW_AMBIENT_SGIX is part of the SGIX_shadow_ambient extension. See
glIntro for more information on using extensions.
ERRORS
GL_INVALID_ENUM is generated if target or pname is not an accepted value.
GL_INVALID_ENUM is generated if pname is GL_TEXTURE_FILTER4_SIZE_SGIS and
target is not GL_TEXTURE_1D or GL_TEXTURE_2D.
GL_INVALID_OPERATION is generated if glGetTexParameter is executed
between the execution of glBegin and the corresponding execution of
glEnd.
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glGetTexParameter(3G) OpenGL Reference glGetTexParameter(3G)
MACHINE DEPENDENCIES
The SGIX_clipmap 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. GL_TEXTURE_WRAP_S and GL_TEXTURE_WRAP_T must be set to
GL_CLAMP_TO_EDGE_SGIS.
4. It is more efficient to set clipmap attributes that affect
texture memory allocation (such as
GL_TEXTURE_CLIPMAP_FRAME_SGIX) before loading the first level of
the clipmap, rather than after loading it.
RealityEngine, RealityEngine2, and VTX systems do not support
GL_DETAIL_TEXTURE_LEVEL_SGIS 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
SGIX_texture_scale_bias extension is not supported on RealityEngine,
RealityEngine2, and VTX systems or on High Impact and Maximum Impact
systems.
The SGIS_texture_select extension is supported only on InfiniteReality
systems and on High Impact and Maximum Impact systems with the TRAM
option card.
The SGIS_texture_filter4 extension is supported only on InfiniteReality
systems.
On InfiniteReality systems, GL_INVALID_VALUE 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
GL_TEXTURE_FILTER4_SIZE_SGIS. This restriction will be removed in a
future release.
SEE ALSO
glTexParameter
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