glTexParameter man page on MacOSX
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GLTEXPARAMETER(3G) OpenGL 3.3 GLTEXPARAMETER(3G)
NAME
glTexParameter - set texture parameters
C SPECIFICATION
void glTexParameterf(GLenum target, GLenum pname, GLfloat param);
void glTexParameteri(GLenum target, GLenum pname, GLint param);
PARAMETERS
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_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.
C SPECIFICATION
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);
PARAMETERS
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_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.
DESCRIPTION
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_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 0.0, 0.0, 0.0, 0.0.
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: f = 2 c + 1 2 b - 1. If specified with
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 │ Computed │
│Comparison Function │ result │
│ │ │
├────────────────────────────────────────────────┼───────────────────────────────────────────────────────────────────────────────┤
│GL_LEQUAL │ <div> │
│ │ │
│ │ │
│ │ result │
│ │ = │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ 1.0 │
│ │ │
│ │ │
│ │ 0.0 │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ r │
│ │ <= │
│ │ │
│ │ D │
│ │ t │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ r │
│ │ > │
│ │ │
│ │ D │
│ │ t │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ </div> │
├────────────────────────────────────────────────┼───────────────────────────────────────────────────────────────────────────────┤
│GL_GEQUAL │ <div> │
│ │ │
│ │ │
│ │ result │
│ │ = │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ 1.0 │
│ │ │
│ │ │
│ │ 0.0 │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ r │
│ │ >= │
│ │ │
│ │ D │
│ │ t │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ r │
│ │ < │
│ │ │
│ │ D │
│ │ t │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ </div> │
├────────────────────────────────────────────────┼───────────────────────────────────────────────────────────────────────────────┤
│GL_LESS │ <div> │
│ │ │
│ │ │
│ │ result │
│ │ = │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ 1.0 │
│ │ │
│ │ │
│ │ 0.0 │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ r │
│ │ < │
│ │ │
│ │ D │
│ │ t │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ r │
│ │ >= │
│ │ │
│ │ D │
│ │ t │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ </div> │
├────────────────────────────────────────────────┼───────────────────────────────────────────────────────────────────────────────┤
│GL_GREATER │ <div> │
│ │ │
│ │ │
│ │ result │
│ │ = │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ 1.0 │
│ │ │
│ │ │
│ │ 0.0 │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ r │
│ │ > │
│ │ │
│ │ D │
│ │ t │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ r │
│ │ <= │
│ │ │
│ │ D │
│ │ t │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ </div> │
├────────────────────────────────────────────────┼───────────────────────────────────────────────────────────────────────────────┤
│GL_EQUAL │ <div> │
│ │ │
│ │ │
│ │ result │
│ │ = │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ 1.0 │
│ │ │
│ │ │
│ │ 0.0 │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ r │
│ │ = │
│ │ │
│ │ D │
│ │ t │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ r │
│ │ ≠ │
│ │ │
│ │ D │
│ │ t │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ </div> │
├────────────────────────────────────────────────┼───────────────────────────────────────────────────────────────────────────────┤
│GL_NOTEQUAL │ <div> │
│ │ │
│ │ │
│ │ result │
│ │ = │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ 1.0 │
│ │ │
│ │ │
│ │ 0.0 │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ r │
│ │ ≠ │
│ │ │
│ │ D │
│ │ t │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ r │
│ │ = │
│ │ │
│ │ D │
│ │ t │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ │
│ │ </div> │
├────────────────────────────────────────────────┼───────────────────────────────────────────────────────────────────────────────┤
│GL_ALWAYS │ <div> │
│ │ │
│ │ result │
│ │ = │
│ │ 1.0 │
│ │ │
│ │ </div> │
├────────────────────────────────────────────────┼───────────────────────────────────────────────────────────────────────────────┤
│GL_NEVER │ <div> │
│ │ │
│ │ result │
│ │ = │
│ │ 0.0 │
│ │ │
│ │ </div> │
└────────────────────────────────────────────────┴───────────────────────────────────────────────────────────────────────────────┘
where r is the current interpolated texture coordinate, and D t is
the depth texture value sampled from the currently bound depth
texture. result is assigned to the 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 r 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_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
- bias max bias max, where bias max is the value of the
implementation defined constant 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 2 n
× 2 m, there are max n m + 1 mipmaps. The first mipmap is the
original texture, with dimensions 2 n × 2 m. Each subsequent mipmap
has dimensions 2 k - 1 × 2 l - 1, where 2 k × 2 l are the
dimensions of the previous mipmap, until either k = 0 or l = 0. At
that point, subsequent mipmaps have dimension 1 × 2 l - 1 or 2 k -
1 × 1 until the final mipmap, which has dimension 1 × 1. 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 1 × 1 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 r 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 r will be taken from
the first channel of the fetched texel. If GL_TEXTURE_SWIZZLE_R is
GL_GREEN, the value for r will be taken from the second channel of
the fetched texel. If GL_TEXTURE_SWIZZLE_R is GL_BLUE, the value
for r will be taken from the third channel of the fetched texel. If
GL_TEXTURE_SWIZZLE_R is GL_ALPHA, the value for r will be taken
from the fourth channel of the fetched texel. If
GL_TEXTURE_SWIZZLE_R is GL_ZERO, the value for r will be subtituted
with 0.0. If GL_TEXTURE_SWIZZLE_R is GL_ONE, the value for r will
be subtituted with 1.0. The initial value is GL_RED.
GL_TEXTURE_SWIZZLE_G
Sets the swizzle that will be applied to the g 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 b 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 a 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_SWIZZLE_RGBA
Sets the swizzles that will be applied to the r, g, b, and a
components of a texel before they are returned to the shader. Valid
values for 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 s to either
GL_CLAMP_TO_EDGE, GL_CLAMP_TO_BORDER, GL_MIRRORED_REPEAT, or
GL_REPEAT. GL_CLAMP_TO_EDGE causes s coordinates to be clamped to
the range 1 2N 1 - 1 2N, where N is the size of the texture in the
direction of clamping. GL_CLAMP_TO_BORDER evaluates s coordinates
in a similar manner to 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
s coordinate to be ignored; the GL uses only the fractional part,
thereby creating a repeating pattern. GL_MIRRORED_REPEAT causes
the s coordinate to be set to the fractional part of the texture
coordinate if the integer part of s is even; if the integer part of
s is odd, then the s texture coordinate is set to 1 - frac s,
where frac s represents the fractional part of s. Initially,
GL_TEXTURE_WRAP_S is set to GL_REPEAT.
GL_TEXTURE_WRAP_T
Sets the wrap parameter for texture coordinate t to either
GL_CLAMP_TO_EDGE, GL_CLAMP_TO_BORDER, 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 r to either
GL_CLAMP_TO_EDGE, GL_CLAMP_TO_BORDER, GL_MIRRORED_REPEAT, or
GL_REPEAT. See the discussion under GL_TEXTURE_WRAP_S. Initially,
GL_TEXTURE_WRAP_R is set to GL_REPEAT.
NOTES
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().
ERRORS
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.
ASSOCIATED GETS
glGetTexParameter()
glGetTexLevelParameter()
SEE ALSO
glActiveTexture(), glBindTexture(), glCopyTexImage1D(),
glCopyTexImage2D(), glCopyTexSubImage1D(), glCopyTexSubImage2D(),
glCopyTexSubImage3D(), glPixelStore(), glSamplerParameter(),
glTexImage1D(), glTexImage2D(), glTexImage3D(), glTexSubImage1D(),
glTexSubImage2D(), glTexSubImage3D()
COPYRIGHT
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed
under the SGI Free Software B License. For details, see
http://oss.sgi.com/projects/FreeB/.
OpenGL 3.3 03/08/2011 GLTEXPARAMETER(3G)
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