GLGETTEXLEVELPARAMETER(3G) 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 tar-gets targets
gets allow the user to more accurately query whether the GL can accommodate a texture of a given con-figuration. configuration.
figuration. 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 argu-ment argument
ment 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 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)
GLGETTEXLEVELPARAMETER(3G)
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