glgettexlevelparameter
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glGetTexLevelParameter(3G) OpenGL Reference 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_EXT, GL_PROXY_TEXTURE_2D_EXT,
GL_PROXY_TEXTURE_3D_EXT, or GL_DETAIL_TEXTURE_2D_SGIS.
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_EXT,
GL_TEXTURE_COMPONENTS, GL_TEXTURE_BORDER,
GL_TEXTURE_RED_SIZE_EXT, GL_TEXTURE_GREEN_SIZE_EXT,
GL_TEXTURE_BLUE_SIZE_EXT, GL_TEXTURE_ALPHA_SIZE_EXT,
GL_TEXTURE_LUMINANCE_SIZE_EXT, and GL_TEXTURE_INTENSITY_SIZE_EXT
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, one of GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D,
GL_PROXY_TEXTURE_1D_EXT, GL_PROXY_TEXTURE_2D_EXT,
GL_PROXY_TEXTURE_3D_EXT, or GL_DETAIL_TEXTURE_2D_SGIS.
GL_MAX_TEXTURE_SIZE is not really descriptive enough. It has to report
the largest square texture image which may be accomodated, but a long
skinny texture may easily fit in texture memory. The proxy targets allow
the user to more accurately query whether the GL can accomodate a texture
of a given configuration. If the texture can not be accomodated, the
texture state variables, which may be queried with
glGetTexLevelParameter, are set to 0. If the texture can be accomodated
the texture state values will be set as they would be set for a non-proxy
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glGetTexLevelParameter(3G) OpenGL Reference glGetTexLevelParameter(3G)
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.
GL_TEXTURE_HEIGHT
params returns a single value, the height of the texture image.
This value includes the border of the texture image.
GL_TEXTURE_DEPTH_EXT
params returns a single value, the depth of the texture image.
This value includes the border of the texture image.
GL_TEXTURE_COMPONENTS
params returns a single value, the level-of-detail's component
as it was specified by the user.
GL_TEXTURE_BORDER
params returns a single value, the width in pixels of the
border of the texture image.
GL_TEXTURE_RED_SIZE_EXT,
GL_TEXTURE_GREEN_SIZE_EXT,
GL_TEXTURE_BLUE_SIZE_EXT,
GL_TEXTURE_ALPHA_SIZE_EXT,
GL_TEXTURE_LUMINANCE_SIZE_EXT, or
GL_TEXTURE_INTENSITY_SIZE_EXT
The internal storage resolution of an individual component.
The format chosen by the GL will be a close match for the
format requested by the user with the component argument of
glTexImage1d, glTexImage2d, or glTexImage3DEXT. These values
for pname query the format chosen by the GL, while
GL_TEXTURE_COMPONENTS is used to query the value requested by
the user.
NOTES
If an error is generated, no change is made to the contents of params.
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glGetTexLevelParameter(3G) OpenGL Reference glGetTexLevelParameter(3G)
GL_TEXTURE_RED_SIZE_EXT, GL_TEXTURE_GREEN_SIZE_EXT,
GL_TEXTURE_BLUE_SIZE_EXT, GL_TEXTURE_ALPHA_SIZE_EXT,
GL_TEXTURE_LUMINANCE_SIZE_EXT, GL_TEXTURE_INTENSITY_SIZE_EXT,
GL_PROXY_TEXTURE_1D_EXT, and GL_PROXY_TEXTURE_2D_EXT, are not supported
in standard GL. texture will be present in the extensions string of
glGetString, if these enumerants are supported. texture3D will be
present if GL_PROXY_TEXTURE_3D_EXT and GL_TEXTURE_3D_EXT are supported.
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 zero or greater than
log max, where max is the returned value of GL_MAX_TEXTURE_SIZE.
2
GL_INVALID_OPERATION is generated if glGetTexLevelParameter is executed
between the execution of glBegin and the corresponding execution of
glEnd.
SEE ALSO
glGetTexParameter, glTexImage1D, glTexImage2D, glTexImage3DEXT,
glTexParameter, glGetString.
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