C SPECIFICATION
void GLAPIENTRY glTexParameterf( GLenum target,
GLenum pname,
GLfloat param )
void GLAPIENTRY glTexParameteri( GLenum target,
GLenum pname,
GLint param )
PARAMETERS
target Specifies the target texture, which must be either
GL_TEXTURE_1D, GL_TEXTURE_2D, or GL_TEXTURE_3D.
pname Specifies the symbolic name of a single-valued texture parame-
ter. pname can be one of the following: GL_TEXTURE_MIN_FILTER,
GL_TEXTURE_MAG_FILTER, GL_TEXTURE_MIN_LOD, GL_TEXTURE_MAX_LOD,
GL_TEXTURE_BASE_LEVEL, GL_TEXTURE_MAX_LEVEL, GL_TEXTURE_WRAP_S,
GL_TEXTURE_WRAP_T, GL_TEXTURE_WRAP_R, or GL_TEXTURE_PRIORITY.
param Specifies the value of pname.
C SPECIFICATION
void GLAPIENTRY glTexParameterfv( GLenum target,
GLenum pnam )
void GLAPIENTRY glTexParameteriv( GLenum target,
GLenum pnam )
PARAMETERS
target Specifies the target texture, which must be either
GL_TEXTURE_1D, GL_TEXTURE_2D or GL_TEXTURE_3D.
pnam Specifies the symbolic name of a texture parameter. pnam can be
one of the following: GL_TEXTURE_MIN_FILTER,
GL_TEXTURE_MAG_FILTER, GL_TEXTURE_MIN_LOD, GL_TEXTURE_MAX_LOD,
GL_TEXTURE_BASE_LEVEL, GL_TEXTURE_MAX_LEVEL, GL_TEXTURE_WRAP_S,
GL_TEXTURE_WRAP_T, GL_TEXTURE_WRAP_R, GL_TEXTURE_BORDER_COLOR,
or GL_TEXTURE_PRIORITY.
Specifies a pointer to an array where the value or values of pnam
are stored.
DESCRIPTION
Texture mapping is a technique that applies an image onto an object's
surface as if the image were a decal or cellophane shrink-wrap. The
image is created in texture space, with an (s, t) coordinate system. A
texture is a one- or two-dimensional image and a set of parameters that
determine how samples are derived from the image.
dimensions 2nx2m, there are max(n,m)+1 mipmaps. The first
mipmap is the original texture, with dimensions 2nx2m. Each
subsequent mipmap has dimensions 2k-1x2l-1, where 2kx2l are
the dimensions of the previous mipmap, until either k=0 or
l=0. At that point, subsequent mipmaps have dimension 1x2l-1
or 2k-1x1 until the final mipmap, which has dimension 1x1.
To define the mipmaps, call glTexImage1D, glTexImage2D,
glTexImage3D, glCopyTexImage1D, or glCopyTexImage2D with the
level argument indicating the order of the mipmaps. Level 0
is the original texture; level max(n,m) is the final 1x1
mipmap.
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 center of
the pixel being textured.
GL_LINEAR Returns the weighted average of the four texture
elements that are closest to the center of the
pixel being textured. These can include border
texture elements, 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 nearest
to the center of the pixel) 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 center of
the pixel) 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 nearest
to the center of the pixel) 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_TEXTURE_MAG_FILTER
The texture magnification function is used when the pixel
being textured maps to an area less than or equal to one tex-
ture element. 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 tex-
ture 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 center of
the pixel being textured.
GL_LINEAR Returns the weighted average of the four texture
elements that are closest to the center of the
pixel being textured. These can include border
texture elements, 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_BASE_LEVEL
Specifies the index of the lowest defined mipmap level. This
is an integer value. The initial value is 0.
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_WRAP_S
Sets the wrap parameter for texture coordinate s to either
GL_CLAMP, GL_CLAMP_TO_EDGE, or GL_REPEAT. GL_CLAMP causes s
coordinates to be clamped to the range [0,1] and is useful
for preventing wrapping artifacts when mapping a single image
to GL_REPEAT.
GL_TEXTURE_WRAP_R
Sets the wrap parameter for texture coordinate r to either
GL_CLAMP, GL_CLAMP_TO_EDGE, or GL_REPEAT. See the discussion
under GL_TEXTURE_WRAP_S. Initially, GL_TEXTURE_WRAP_R is set
to GL_REPEAT.
GL_TEXTURE_BORDER_COLOR
Sets a border color.
contains four values that comprise the RGBA color of the
texture border. Integer color components are interpreted
linearly such that the most positive integer maps to 1.0, and
the most negative integer maps to -1.0. The values are
clamped to the range [0,1] when they are specified. Ini-
tially, the border color is (0, 0, 0, 0).
GL_TEXTURE_PRIORITY
Specifies the texture residence priority of the currently
bound texture. Permissible values are in the range [0, 1].
See glPrioritizeTextures and glBindTexture for more informa-
tion.
NOTES
GL_TEXTURE_3D, GL_TEXTURE_MIN_LOD, GL_TEXTURE_MAX_LOD,
GL_TEXTURE_BASE_LEVEL, and GL_TEXTURE_MAX_LEVEL are only available if
the GL version is 1.2 or greater.
Suppose that a program has enabled texturing (by calling glEnable with
argument GL_TEXTURE_1D, GL_TEXTURE_2D, or GL_TEXTURE_3D) 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 dif-
fering numbers of texture components, then it is as if texture mapping
were disabled.
Linear filtering accesses the four nearest texture elements only in 2D
textures. In 1D textures, linear filtering accesses the two nearest
texture elements.
When the GL_ARB_multitexture extension is supported, glTexParameter
specifies the texture parameters for the active texture unit, specified
by calling glActiveTextureARB.
ERRORS
GL_INVALID_ENUM is generated if target or pnam is not one of the
accepted defined values.
GL_INVALID_ENUM is generated if should have a defined constant value
glTexImage3D, glTexSubImage1D, glTexSubImage2D, glTexSubImage3D
GLTEXPARAMETER(3G)
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