glTexParameter — set texture parameters
void glTexParameterf(
|
GLenum target, |
GLenum pname, | |
GLfloat param) ; |
void glTexParameteri(
|
GLenum target, |
GLenum pname, | |
GLint param) ; |
void glTexParameterfv(
|
GLenum target, |
GLenum pname, | |
const GLfloat * params) ; |
void glTexParameteriv(
|
GLenum target, |
GLenum pname, | |
const GLint * params) ; |
target
Specifies the target texture,
which must be either GL_TEXTURE_2D
,
GL_TEXTURE_3D
,
GL_TEXTURE_2D_ARRAY
,
GL_TEXTURE_2D_MULTISAMPLE
,
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_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
.
params
For the vector commands, 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_2D
, GL_TEXTURE_CUBE_MAP
,
GL_TEXTURE_2D_ARRAY
, GL_TEXTURE_2D_MULTISAMPLE
, 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_INDEX
.
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
and the stencil component
will be discarded. If the depth stencil mode is GL_STENCIL_INDEX
then
the stencil component is returned in
and the depth component is discarded. The initial value is 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_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 is the current interpolated texture coordinate, and is the depth texture value sampled from the currently bound depth texture. is assigned to the red channel.
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
texture coordinate should
be compared to the value in the currently bound depth texture. See the
discussion of 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_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 , there are mipmaps. The first mipmap is the original texture, with dimensions . Each subsequent mipmap has dimensions , where are the dimensions of the previous mipmap, until either or . At that point, subsequent mipmaps have dimension or until the final mipmap, which has dimension . To define the mipmaps, call glTexImage2D, glTexImage3D, or glCopyTexImage2D with the level argument indicating the order of the mipmaps. Level 0 is the original texture; level is the final mipmap.
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
component of a texel before it is returned to the shader. Valid values for 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
will be taken from the first
channel of the fetched texel.
If GL_TEXTURE_SWIZZLE_R
is GL_GREEN
, the value for
will be taken from the second
channel of the fetched texel.
If GL_TEXTURE_SWIZZLE_R
is GL_BLUE
, the value for
will be taken from the third
channel of the fetched texel.
If GL_TEXTURE_SWIZZLE_R
is GL_ALPHA
, the value for
will be taken from the fourth
channel of the fetched texel.
If GL_TEXTURE_SWIZZLE_R
is GL_ZERO
, the value for
will be subtituted with
.
If GL_TEXTURE_SWIZZLE_R
is GL_ONE
, the value for
will be subtituted with
for integer texture components, otherwise
.
The initial value is GL_RED
.
GL_TEXTURE_SWIZZLE_G
Sets the swizzle that will be applied to the
component of a texel before it is returned to the shader. Valid values for 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
component of a texel before it is returned to the shader. Valid values for 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
component of a texel before it is returned to the shader. Valid values for param
and their effects are similar to
those of GL_TEXTURE_SWIZZLE_R
.
The initial value is GL_ALPHA
.
GL_TEXTURE_WRAP_S
Sets the wrap parameter for texture coordinate
to either GL_CLAMP_TO_EDGE
,
GL_MIRRORED_REPEAT
, or
GL_REPEAT
. GL_CLAMP_TO_EDGE
causes
coordinates to be clamped to the
range
,
where
is the size
of the texture in the direction of clamping.
GL_REPEAT
causes the
integer part of the
coordinate to be ignored; the GL uses only the
fractional part, thereby creating a repeating pattern.
GL_MIRRORED_REPEAT
causes the
coordinate to be set to the
fractional part of the texture coordinate if the integer part of
is
even; if the integer part of
is odd, then the
texture coordinate is
set to
,
where
represents the fractional part of
.
Initially, GL_TEXTURE_WRAP_S
is set to GL_REPEAT
.
GL_TEXTURE_WRAP_T
Sets the wrap parameter for texture coordinate
to either GL_CLAMP_TO_EDGE
,
GL_MIRRORED_REPEAT
, or
GL_REPEAT
. 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
to either GL_CLAMP_TO_EDGE
,
GL_MIRRORED_REPEAT
, or
GL_REPEAT
. 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 glTexStorage2D,
glTexImage2D,
glTexStorage3D,
glTexImage3D,
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 3D textures, linear filtering accesses the eight nearest texture elements.
glTexParameter
specifies the texture parameters for the texture object bound to the
active texture unit, specified by calling glActiveTexture.
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.
GL_INVALID_ENUM
is generated if the target is GL_TEXTURE_2D_MULTISAMPLE
and
pname
is any of the sampler states.
GL_INVALID_OPERATION
is generated if the target is GL_TEXTURE_2D_MULTISAMPLE
and pname GL_TEXTURE_BASE_LEVEL
is set to a value other than zero.
GL_INVALID_VALUE
is generated if pname
is GL_TEXTURE_BASE_LEVEL
or GL_TEXTURE_MAX_LEVEL
, and param
or params
is negative.
OpenGL ES API Version | |||
---|---|---|---|
Function Name | 2.0 | 3.0 | 3.1 |
glTexParameterf
|
✔ | ✔ | ✔ |
glTexParameterfv
|
✔ | ✔ | ✔ |
glTexParameteri
|
✔ | ✔ | ✔ |
glTexParameteriv
|
✔ | ✔ | ✔ |
glActiveTexture, glBindTexture, glCopyTexImage2D, glCopyTexSubImage2D, glCopyTexSubImage3D, glPixelStorei, glSamplerParameter, glTexStorage2D, glTexImage2D, glTexStorage3D, glTexImage3D, glTexSubImage2D, glTexSubImage3D
Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010-2015 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see https://khronos.org/registry/OpenGL-Refpages/LICENSES/LicenseRef-FreeB.txt.