GLGETTEXLEVELPARAMETEUNIX)Programmer's GLGETTEXLEVELPARAMETER(3G)
NAME
glGetTexLevelParameterfv, glGetTexLevelParameteriv - return
texture parameter values for a specific level of detail
C SPECIFICATION
void glGetTexLevelParameterfv( GLenum target,
GLint level,
GLenum pname,
GLfloat *params )
void glGetTexLevelParameteriv( GLenum target,
GLint level,
GLenum pname,
GLint *params )
PARAMETERS
target Specifies the symbolic name of the target texture,
either GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D,
GL_PROXY_TEXTURE_1D, GL_PROXY_TEXTURE_2D, or
GL_PROXY_TEXTURE_3D.
level Specifies the level-of-detail number of the desired
image. Level 0 is the base image level. Level n is
the nth mipmap reduction image.
pname Specifies the symbolic name of a texture parameter.
GL_TEXTURE_WIDTH, GL_TEXTURE_HEIGHT,
GL_TEXTURE_DEPTH, GL_TEXTURE_INTERNAL_FORMAT,
GL_TEXTURE_BORDER, GL_TEXTURE_RED_SIZE,
GL_TEXTURE_GREEN_SIZE, GL_TEXTURE_BLUE_SIZE,
GL_TEXTURE_ALPHA_SIZE, GL_TEXTURE_LUMINANCE_SIZE,
and GL_TEXTURE_INTENSITY_SIZE are accepted.
params Returns the requested data.
DESCRIPTION
glGetTexLevelParameter returns in params texture parameter
values for a specific level-of-detail value, specified as
level. target defines the target texture, either
GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D,
GL_PROXY_TEXTURE_1D, GL_PROXY_TEXTURE_2D, or
GL_PROXY_TEXTURE_3D.
GL_MAX_TEXTURE_SIZE, and GL_MAX_3D_TEXTURE_SIZE are not
really descriptive enough. It has to report the largest
square texture image that can be accommodated with mipmaps
and borders, but a long skinny texture, or a texture without
mipmaps and borders, may easily fit in texture memory. The
proxy targets allow the user to more accurately query
whether the GL can accommodate a texture of a given confi-
guration. If the texture cannot be accommodated, the texture
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GLGETTEXLEVELPARAMETEUNIX)Programmer's GLGETTEXLEVELPARAMETER(3G)
state variables, which may be queried with
glGetTexLevelParameter, are set to 0. If the texture can be
accommodated, the texture state values will be set as they
would be set for a non-proxy target.
pname specifies the texture parameter whose value or values
will be returned.
The accepted parameter names are as follows:
GL_TEXTURE_WIDTH
params returns a single value, the width of the
texture image. This value includes the border of
the texture image. The initial value is 0.
GL_TEXTURE_HEIGHT
params returns a single value, the height of the
texture image. This value includes the border of
the texture image. The initial value is 0.
GL_TEXTURE_DEPTH
params returns a single value, the depth of the
texture image. This value includes the border of
the texture image. The initial value is 0.
GL_TEXTURE_INTERNAL_FORMAT
params returns a single value, the internal of
the texture image.
GL_TEXTURE_BORDER
params returns a single value, the width in pixels
of the border of the texture image. The initial
value is 0.
GL_TEXTURE_RED_SIZE,
GL_TEXTURE_GREEN_SIZE,
GL_TEXTURE_BLUE_SIZE,
GL_TEXTURE_ALPHA_SIZE,
GL_TEXTURE_LUMINANCE_SIZE,
GL_TEXTURE_INTENSITY_SIZE
The internal storage resolution of an individual
component. The resolution chosen by the GL will be
a close match for the resolution requested by the
user with the component argument of glTexImage1D,
glTexImage2D, glTexImage3D, glCopyTexImage1D, and
glCopyTexImage2D. The initial value is 0.
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GLGETTEXLEVELPARAMETEUNIX)Programmer's GLGETTEXLEVELPARAMETER(3G)
NOTES
If an error is generated, no change is made to the contents
of params.
GL_TEXTURE_INTERNAL_FORMAT is available only if the GL ver-
sion is 1.1 or greater. In version 1.0, use
GL_TEXTURE_COMPONENTS instead.
GL_PROXY_TEXTURE_1D and GL_PROXY_TEXTURE_2D are available
only if the GL version is 1.1 or greater.
GL_TEXTURE_3D, GL_PROXY_TEXTURE_3D, and GL_TEXTURE_DEPTH are
available only if the GL version is 1.2 or greater.
When the GL_ARB_multitexture extension is supported,
glGetTexLevelParameter returns the texture level parameters
for the active texture unit.
ERRORS
GL_INVALID_ENUM is generated if target or pname is not an
accepted value.
GL_INVALID_VALUE is generated if level is less than 0.
GL_INVALID_VALUE may be generated if level is greater than
log2 max, where max is the returned value of
GL_MAX_TEXTURE_SIZE.
GL_INVALID_OPERATION is generated if glGetTexLevelParameter
is executed between the execution of glBegin and the
corresponding execution of glEnd.
SEE ALSO
glActiveTextureARB(3G), glGetTexParameter(3G),
glCopyTexImage1D(3G), glCopyTexImage2D(3G),
glCopyTexSubImage1D(3G), glCopyTexSubImage2D(3G),
glCopyTexSubImage3D(3G), glTexEnv(3G), glTexGen(3G),
glTexImage1D(3G), glTexImage2D(3G), glTexImage3D(3G),
glTexSubImage1D(3G), glTexSubImage2D(3G),
glTexSubImage3D(3G), glTexParameter(3G)
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