glTexParameter — set texture parameters
void glTexParameterf( | GLenum target, |
GLenum pname, | |
GLfloat param) ; |
void glTexParameteri( | GLenum target, |
GLenum pname, | |
GLint param) ; |
target
Specifies the target texture,
which must be either GL_TEXTURE_1D
, GL_TEXTURE_2D
,
GL_TEXTURE_3D
, GL_TEXTURE_1D_ARRAY
,
GL_TEXTURE_2D_ARRAY
, GL_TEXTURE_RECTANGLE
,
or GL_TEXTURE_CUBE_MAP
.
pname
Specifies the symbolic name of a single-valued texture parameter.
pname
can be one of the following:
GL_DEPTH_STENCIL_TEXTURE_MODE
,
GL_TEXTURE_BASE_LEVEL
,
GL_TEXTURE_COMPARE_FUNC
,
GL_TEXTURE_COMPARE_MODE
,
GL_TEXTURE_LOD_BIAS
,
GL_TEXTURE_MIN_FILTER
,
GL_TEXTURE_MAG_FILTER
,
GL_TEXTURE_MIN_LOD
,
GL_TEXTURE_MAX_LOD
,
GL_TEXTURE_MAX_LEVEL
,
GL_TEXTURE_SWIZZLE_R
,
GL_TEXTURE_SWIZZLE_G
,
GL_TEXTURE_SWIZZLE_B
,
GL_TEXTURE_SWIZZLE_A
,
GL_TEXTURE_WRAP_S
,
GL_TEXTURE_WRAP_T
, or
GL_TEXTURE_WRAP_R
.
param
Specifies the value of pname
.
void glTexParameterfv( | GLenum target, |
GLenum pname, | |
const GLfloat * params) ; |
void glTexParameteriv( | GLenum target, |
GLenum pname, | |
const GLint * params) ; |
void glTexParameterIiv( | GLenum target, |
GLenum pname, | |
const GLint * params) ; |
void glTexParameterIuiv( | GLenum target, |
GLenum pname, | |
const GLuint * params) ; |
target
Specifies the target texture,
which must be either GL_TEXTURE_1D
, GL_TEXTURE_2D
,
GL_TEXTURE_3D
, GL_TEXTURE_1D_ARRAY
,
GL_TEXTURE_2D_ARRAY
, GL_TEXTURE_RECTANGLE
,
or GL_TEXTURE_CUBE_MAP
.
pname
Specifies the symbolic name of a texture parameter.
pname
can be one of the following:
GL_DEPTH_STENCIL_TEXTURE_MODE
,
GL_TEXTURE_BASE_LEVEL
,
GL_TEXTURE_BORDER_COLOR
,
GL_TEXTURE_COMPARE_FUNC
,
GL_TEXTURE_COMPARE_MODE
,
GL_TEXTURE_LOD_BIAS
,
GL_TEXTURE_MIN_FILTER
,
GL_TEXTURE_MAG_FILTER
,
GL_TEXTURE_MIN_LOD
,
GL_TEXTURE_MAX_LOD
,
GL_TEXTURE_MAX_LEVEL
,
GL_TEXTURE_SWIZZLE_R
,
GL_TEXTURE_SWIZZLE_G
,
GL_TEXTURE_SWIZZLE_B
,
GL_TEXTURE_SWIZZLE_A
,
GL_TEXTURE_SWIZZLE_RGBA
,
GL_TEXTURE_WRAP_S
,
GL_TEXTURE_WRAP_T
, or
GL_TEXTURE_WRAP_R
.
params
Specifies a pointer to an array where the value or values of pname
are stored.
glTexParameter
assigns the value or values in params
to the texture parameter
specified as pname
.
target
defines the target texture,
either GL_TEXTURE_1D
, GL_TEXTURE_2D
, GL_TEXTURE_1D_ARRAY
,
GL_TEXTURE_2D_ARRAY
, GL_TEXTURE_RECTANGLE
, or GL_TEXTURE_3D
.
The following symbols are accepted in pname
:
GL_DEPTH_STENCIL_TEXTURE_MODE
Specifies the mode used to read from depth-stencil format textures. params
must be one of GL_DEPTH_COMPONENT
or GL_STENCIL_COMPONENT
.
If the depth stencil mode is GL_DEPTH_COMPONENT
, then reads from depth-stencil
format textures will return the depth component of the texel in
GL_STENCIL_COMPONENT
then
the stencil component is returned in GL_DEPTH_COMPONENT
.
GL_TEXTURE_BASE_LEVEL
Specifies the index of the lowest defined mipmap level. This is an integer value. The initial value is 0.
GL_TEXTURE_BORDER_COLOR
The data in params
specifies four values that define the border values that
should be used for border texels. If a texel is sampled from the border of the texture, the
values of GL_TEXTURE_BORDER_COLOR
are interpreted as an RGBA color to match the
texture's internal format and substituted for the non-existent texel data. If the texture contains depth
components, the first component of GL_TEXTURE_BORDER_COLOR
is interpreted as a depth value.
The initial value is
If the values for GL_TEXTURE_BORDER_COLOR
are specified with glTexParameterIiv
or glTexParameterIuiv
, the values are stored unmodified with an internal data type of
integer. If specified with glTexParameteriv
, they are converted to floating point with the following
equation:
glTexParameterfv
, they are stored unmodified as floating-point values.
GL_TEXTURE_COMPARE_FUNC
Specifies the comparison operator used when GL_TEXTURE_COMPARE_MODE
is
set to GL_COMPARE_REF_TO_TEXTURE
. Permissible values are:
Texture Comparison Function | Computed result |
---|---|
GL_LEQUAL
|
|
GL_GEQUAL
|
|
GL_LESS
|
|
GL_GREATER
|
|
GL_EQUAL
|
|
GL_NOTEQUAL
|
|
GL_ALWAYS
|
|
GL_NEVER
|
|
where
GL_TEXTURE_COMPARE_MODE
Specifies the texture comparison mode for currently bound depth textures.
That is, a texture whose internal format is GL_DEPTH_COMPONENT_*
; see
glTexImage2D)
Permissible values are:
GL_COMPARE_REF_TO_TEXTURE
Specifies that the interpolated and clamped
GL_TEXTURE_COMPARE_FUNC
for details of how the comparison
is evaluated. The result of the comparison is assigned to the red channel.
GL_NONE
Specifies that the red channel should be assigned the appropriate value from the currently bound depth texture.
GL_TEXTURE_LOD_BIAS
params
specifies a fixed bias value that is to be added to the level-of-detail
parameter for the texture before texture sampling. The specified value is added to the shader-supplied
bias value (if any) and subsequently clamped into the implementation-defined range
GL_MAX_TEXTURE_LOD_BIAS
. The initial value is 0.0.
GL_TEXTURE_MIN_FILTER
The texture minifying function is used whenever the level-of-detail function used when sampling from the texture determines that the texture should be minified. There are six defined minifying functions. Two of them use either the nearest texture elements or a weighted average of multiple texture elements to compute the texture value. The other four use mipmaps.
A mipmap is an ordered set of arrays representing the same image
at progressively lower resolutions.
If the texture has dimensions
params
supplies a function for minifying the texture as one of the
following:
GL_NEAREST
Returns the value of the texture element that is nearest (in Manhattan distance) to the specified texture coordinates.
GL_LINEAR
Returns the weighted average of the four texture elements
that are closest to the specified texture coordinates.
These can include items wrapped or repeated from other parts of a texture,
depending on the values of GL_TEXTURE_WRAP_S
and GL_TEXTURE_WRAP_T
,
and on the exact mapping.
GL_NEAREST_MIPMAP_NEAREST
Chooses the mipmap that most closely matches the size of the pixel
being textured and uses the GL_NEAREST
criterion
(the texture element closest to the specified texture coordinates)
to produce a texture value.
GL_LINEAR_MIPMAP_NEAREST
Chooses the mipmap that most closely matches the size of the pixel
being textured and uses the GL_LINEAR
criterion
(a weighted average of the four texture elements that are closest to the specified texture coordinates)
to produce a texture value.
GL_NEAREST_MIPMAP_LINEAR
Chooses the two mipmaps that most closely match the size of the pixel
being textured and uses the GL_NEAREST
criterion
(the texture element closest to the specified texture coordinates )
to produce a texture value from each mipmap.
The final texture value is a weighted average of those two values.
GL_LINEAR_MIPMAP_LINEAR
Chooses the two mipmaps that most closely match the size of the pixel
being textured and uses the GL_LINEAR
criterion
(a weighted average of the texture elements that are closest to the specified texture coordinates)
to produce a texture value from each mipmap.
The final texture value is a weighted average of those two values.
As more texture elements are sampled in the minification process,
fewer aliasing artifacts will be apparent.
While the GL_NEAREST
and GL_LINEAR
minification functions can be
faster than the other four,
they sample only one or multiple texture elements to determine the texture value
of the pixel being rendered and can produce moire patterns
or ragged transitions.
The initial value of GL_TEXTURE_MIN_FILTER
is
GL_NEAREST_MIPMAP_LINEAR
.
GL_TEXTURE_MAG_FILTER
The texture magnification function is used whenever the level-of-detail function
used when sampling from the texture determines that the texture should be magified.
It sets the texture magnification function to either GL_NEAREST
or GL_LINEAR
(see below). GL_NEAREST
is generally faster
than GL_LINEAR
,
but it can produce textured images with sharper edges
because the transition between texture elements is not as smooth.
The initial value of GL_TEXTURE_MAG_FILTER
is GL_LINEAR
.
GL_NEAREST
Returns the value of the texture element that is nearest (in Manhattan distance) to the specified texture coordinates.
GL_LINEAR
Returns the weighted average of the texture elements
that are closest to the specified texture coordinates.
These can include items wrapped or repeated from other parts of a texture,
depending on the values of GL_TEXTURE_WRAP_S
and GL_TEXTURE_WRAP_T
,
and on the exact mapping.
GL_TEXTURE_MIN_LOD
Sets the minimum level-of-detail parameter. This floating-point value limits the selection of highest resolution mipmap (lowest mipmap level). The initial value is -1000.
GL_TEXTURE_MAX_LOD
Sets the maximum level-of-detail parameter. This floating-point value limits the selection of the lowest resolution mipmap (highest mipmap level). The initial value is 1000.
GL_TEXTURE_MAX_LEVEL
Sets the index of the highest defined mipmap level. This is an integer value. The initial value is 1000.
GL_TEXTURE_SWIZZLE_R
Sets the swizzle that will be applied to the param
are GL_RED
,
GL_GREEN
, GL_BLUE
, GL_ALPHA
, GL_ZERO
and
GL_ONE
.
If GL_TEXTURE_SWIZZLE_R
is GL_RED
, the value for
GL_TEXTURE_SWIZZLE_R
is GL_GREEN
, the value for
GL_TEXTURE_SWIZZLE_R
is GL_BLUE
, the value for
GL_TEXTURE_SWIZZLE_R
is GL_ALPHA
, the value for
GL_TEXTURE_SWIZZLE_R
is GL_ZERO
, the value for
GL_TEXTURE_SWIZZLE_R
is GL_ONE
, the value for
GL_RED
.
GL_TEXTURE_SWIZZLE_G
Sets the swizzle that will be applied to the param
and their effects are similar to
those of GL_TEXTURE_SWIZZLE_R
.
The initial value is GL_GREEN
.
GL_TEXTURE_SWIZZLE_B
Sets the swizzle that will be applied to the param
and their effects are similar to
those of GL_TEXTURE_SWIZZLE_R
.
The initial value is GL_BLUE
.
GL_TEXTURE_SWIZZLE_A
Sets the swizzle that will be applied to the param
and their effects are similar to
those of GL_TEXTURE_SWIZZLE_R
.
The initial value is GL_ALPHA
.
GL_TEXTURE_SWIZZLE_RGBA
Sets the swizzles that will be applied to the
params
and their effects are similar to
those of GL_TEXTURE_SWIZZLE_R
, except that all channels are specified simultaneously.
Setting the value of GL_TEXTURE_SWIZZLE_RGBA
is equivalent (assuming no errors are generated) to
setting the parameters of each of GL_TEXTURE_SWIZZLE_R
,
GL_TEXTURE_SWIZZLE_G
,
GL_TEXTURE_SWIZZLE_B
, and
GL_TEXTURE_SWIZZLE_A
successively.
GL_TEXTURE_WRAP_S
Sets the wrap parameter for texture coordinate
GL_CLAMP_TO_EDGE
, GL_CLAMP_TO_BORDER
,
GL_MIRRORED_REPEAT
,
GL_REPEAT
, or GL_MIRROR_CLAMP_TO_EDGE
. GL_CLAMP_TO_EDGE
causes
GL_CLAMP_TO_BORDER
evaluates GL_CLAMP_TO_EDGE
.
However, in cases where clamping would have occurred in GL_CLAMP_TO_EDGE
mode, the fetched texel data
is substituted with the values specified by GL_TEXTURE_BORDER_COLOR
.
GL_REPEAT
causes the
integer part of the
GL_MIRRORED_REPEAT
causes the
GL_MIRROR_CLAMP_TO_EDGE
causes the the GL_MIRRORED_REPEAT
for one reptition of the texture,
at which point the coordinate to be clamped as in GL_CLAMP_TO_EDGE
.
Initially, GL_TEXTURE_WRAP_S
is set to GL_REPEAT
.
GL_TEXTURE_WRAP_T
Sets the wrap parameter for texture coordinate
GL_CLAMP_TO_EDGE
, GL_CLAMP_TO_BORDER
,
GL_MIRRORED_REPEAT
, GL_REPEAT
, or
GL_MIRROR_CLAMP_TO_EDGE
. See the discussion under GL_TEXTURE_WRAP_S
.
Initially, GL_TEXTURE_WRAP_T
is set to GL_REPEAT
.
GL_TEXTURE_WRAP_R
Sets the wrap parameter for texture coordinate
GL_CLAMP_TO_EDGE
, GL_CLAMP_TO_BORDER
,
GL_MIRRORED_REPEAT
, GL_REPEAT
, or
GL_MIRROR_CLAMP_TO_EDGE
. See the discussion under GL_TEXTURE_WRAP_S
.
Initially, GL_TEXTURE_WRAP_R
is set to GL_REPEAT
.
Suppose that a program attempts to sample from a texture and
has set GL_TEXTURE_MIN_FILTER
to one of the functions that requires a
mipmap. If either the dimensions of the texture images currently defined
(with previous calls to glTexImage1D, glTexImage2D,
glTexImage3D, glCopyTexImage1D, or glCopyTexImage2D) do not
follow the proper sequence for mipmaps (described above), or there are
fewer texture images defined than are needed, or the set of texture images
have differing numbers of texture components, then the texture is considered incomplete.
Linear filtering accesses the four nearest texture elements only in 2D textures. In 1D textures, linear filtering accesses the two nearest texture elements. In 3D textures, linear filtering accesses the eight nearest texture elements.
glTexParameter
specifies the texture parameters for the active texture unit, specified
by calling glActiveTexture.
GL_DEPTH_STENCIL_TEXTURE_MODE
is available only if the GL version is 4.3 or greater.
GL_MIRROR_CLAMP_TO_EDGE
is available only if the GL version is 4.4 or greater.
GL_INVALID_ENUM
is generated if target
or pname
is not
one of the accepted defined values.
GL_INVALID_ENUM
is generated if params
should have a defined
constant value (based on the value of pname
) and does not.
glActiveTexture, glBindTexture, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, glCopyTexSubImage3D, glPixelStore, glSamplerParameter, glTexImage1D, glTexImage2D, glTexImage3D, glTexSubImage1D, glTexSubImage2D, glTexSubImage3D
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