glGetTexLevelParameter man page on Oracle
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GLGETTEXLEVELPARAMET(3G) OpenGL Manual GLGETTEXLEVELPARAMET(3G)
NAME
glGetTexLevelParameter - 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, one of
GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D, GL_TEXTURE_1D_ARRAY,
GL_TEXTURE_2D_ARRAY, GL_TEXTURE_RECTANGLE,
GL_TEXTURE_2D_MULTISAMPLE, GL_TEXTURE_2D_MULTISAMPLE_ARRAY,
GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X,
GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y,
GL_TEXTURE_CUBE_MAP_POSITIVE_Z, GL_TEXTURE_CUBE_MAP_NEGATIVE_Z,
GL_PROXY_TEXTURE_1D, GL_PROXY_TEXTURE_2D, GL_PROXY_TEXTURE_3D,
GL_PROXY_TEXTURE_1D_ARRAY, GL_PROXY_TEXTURE_2D_ARRAY,
GL_PROXY_TEXTURE_RECTANGLE, GL_PROXY_TEXTURE_2D_MULTISAMPLE,
GL_PROXY_TEXTURE_2D_MULTISAMPLE_ARRAY, GL_PROXY_TEXTURE_CUBE_MAP,
or GL_TEXTURE_BUFFER.
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_DEPTH_SIZE, GL_TEXTURE_COMPRESSED,
GL_TEXTURE_COMPRESSED_IMAGE_SIZE, and GL_TEXTURE_BUFFER_OFFSET 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, GL_PROXY_TEXTURE_3D,
GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X,
GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y,
GL_TEXTURE_CUBE_MAP_POSITIVE_Z, GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, or
GL_PROXY_TEXTURE_CUBE_MAP.
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
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 format of the texture
image.
GL_TEXTURE_RED_TYPE,
GL_TEXTURE_GREEN_TYPE,
GL_TEXTURE_BLUE_TYPE,
GL_TEXTURE_ALPHA_TYPE,
GL_TEXTURE_DEPTH_TYPE
The data type used to store the component. The types GL_NONE,
GL_SIGNED_NORMALIZED, GL_UNSIGNED_NORMALIZED, GL_FLOAT, GL_INT, and
GL_UNSIGNED_INT may be returned to indicate signed normalized
fixed-point, unsigned normalized fixed-point, floating-point,
integer unnormalized, and unsigned integer unnormalized components,
respectively.
GL_TEXTURE_RED_SIZE,
GL_TEXTURE_GREEN_SIZE,
GL_TEXTURE_BLUE_SIZE,
GL_TEXTURE_ALPHA_SIZE,
GL_TEXTURE_DEPTH_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.
GL_TEXTURE_COMPRESSED
params returns a single boolean value indicating if the texture
image is stored in a compressed internal format. The initiali value
is GL_FALSE.
GL_TEXTURE_COMPRESSED_IMAGE_SIZE
params returns a single integer value, the number of unsigned bytes
of the compressed texture image that would be returned from
glGetCompressedTexImage().
GL_TEXTURE_BUFFER_OFFSET
params returns a single integer value, the offset into the data
store of the buffer bound to a buffer texture. glTexBufferRange().
GL_TEXTURE_BUFFER_SIZE
params returns a single integer value, the size of the range of a
data store of the buffer bound to a buffer texture.
glTexBufferRange().
NOTES
If an error is generated, no change is made to the contents of params.
glGetTexLevelParameter returns the texture level parameters for the
active texture unit.
GL_TEXTURE_BUFFER_OFFSET and GL_TEXTURE_BUFFER_SIZE are available only
if the GL version is 4.3 or greater.
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 2max,
where max is the returned value of GL_MAX_TEXTURE_SIZE.
GL_INVALID_VALUE is generated if target is GL_TEXTURE_BUFFER and level
is not zero.
GL_INVALID_OPERATION is generated if GL_TEXTURE_COMPRESSED_IMAGE_SIZE
is queried on texture images with an uncompressed internal format or on
proxy targets.
SEE ALSO
glActiveTexture(), glGetTexParameter(), glCopyTexImage1D(),
glCopyTexImage2D(), glCopyTexSubImage1D(), glCopyTexSubImage2D(),
glCopyTexSubImage3D(), glTexImage1D(), glTexImage2D(), glTexImage3D(),
glTexSubImage1D(), glTexSubImage2D(), glTexSubImage3D(),
glTexParameter()
COPYRIGHT
Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010-2012
Khronos Group. This document is licensed under the SGI Free Software B
License. For details, see http://oss.sgi.com/projects/FreeB/.
AUTHORS
opengl.org
opengl.org 04/29/2014 GLGETTEXLEVELPARAMET(3G)
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