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 )
delim $$
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 $n$th 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.
.PGL_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 configuration.
If the texture cannot be accommodated, the texture 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.
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 version 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 $ log sub 2$ 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.
