GLGETMINMAXEXT(3GL)GLGETMINMAXEXT(3GL)NAME
glGetMinmaxEXT, glGetMinmaxParameterivEXT, glGetMinmaxParameterfvEXT -
gets minmax values and minmax related parameters
C SPECIFICATION
void glGetMinmaxEXT ( GLenum target,
GLboolean reset,
GLenum format,
GLenum type'
GLvoid *values)
PARAMETERS
target The target minmax to be queried for the minmax values. Must be
GL_MINMAX_EXT.
reset Specifies whether or not to reset the current minmax compo‐
nents that have been queried. Must be GL_TRUE or GL_FALSE.
format Format the caller wants the minmax values returned in. Must be
one of GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_RGBA,
GL_ABGR_EXT, GL_LUMINANCE, or GL_LUMINANCE_ALPHA.
type Data type the caller wants the minmax values returned in. Must
be one of GL_BYTE, GL_UNSIGNED_BYTE, GL_SHORT,
GL_UNSIGNED_SHORT, GL_INT, GL_UNSIGNED_INT, or GL_FLOAT.
value
Pointer to area of memory large enough to contain the returned
minmax values. (Should have num_format_compo‐
nents*sizeof(type) bytes.)
C SPECIFICATION
void glGetMinmaxParameterivEXT ( GLenum target,
GLenum pname,
GLint* *params)
void glGetMinmaxParameterfvEXT ( GLenum target,
GLenum pname,
GLfloat* *params)
PARAMETERS
target The target minmax to be queried. Must be GL_MINMAX_EXT.
pname Parameter name. Must be one of GL_MINMAX_FORMAT_EXT or GL_MIN‐
MAX_SINK_EXT.
params Pointer to a single integer or floating point memory location
to contain the retrieved value.
DESCRIPTION
glGetMinmaxEXT, glGetMinmaxParameterivEXT, and glGetMinmaxParame‐
terivEXT are part of the EXT_histogram extension, which defines his‐
togram and minmax operations at a fixed location in the pixel transfer
pipeline after convolution and post convolution colortable.
The minmax operation immediately follows the histogram operation, but
will only be executed if both the histogram and minmax operations are
enabled. Also, if the sink value for histogram is set to GL_TRUE, then
the minmax operation will not be executed.
The current contents of the minmax tables are queried using glGetMin‐
maxEXT. <target> must be GL_MINMAX_EXT. <format> must be one of
GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_RGBA, GL_ABGR_EXT,
GL_LUMINANCE, or GL_LUMINANCE_ALPHA. <type> must be GL_UNSIGNED_BYTE,
GL_BYTE, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT, GL_INT, or
GL_FLOAT. A 1-dimensional image with width of 2 is returned to values.
No pixel transfer operations are performed on this image, but pixel
storage modes that are applicable to ReadPixels are performed. Color
components that are requested in the specified <format>, but which are
not included in the internal format of the minmax table, are returned
as zero. The assignment of internal color components to the components
requested by <format> are the same as for those which histogram
returns.
<reset> is either GL_TRUE or GL_FALSE. If GL_TRUE, each minimum value
that is actually returned is reset to the maximum representable value,
and each maximum value that is returned is reset to the minimum repre‐
sentable value. Minimum and maximum values that are not returned are
not modified. All minimum and maximum values of minmax table <target>
are reset to their maximum and minimum representable values, respec‐
tively, when glResetMinmaxEXT is called. <target> must be GL_MIN‐
MAX_EXT.
The integer and floating point query functions glGetMinmaxParame‐
terivEXT and glGetMinmaxParameterfvEXT are provided. <target> must be
GL_MINMAX_EXT. <pname> is GL_MINMAX_FORMAT_EXT or GL_MINMAX_SINK_EXT.
The value of the specified parameter is returned in <params>.
ERRORS
GL_INVALID_ENUM is generated if glGetMinmaxEXT parameter <target> is
not GL_MINMAX_EXT.
GL_INVALID_ENUM is generated if glGetMinmaxEXT parameter <format> is
not GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_RGBA, GL_ABGR_EXT,
GL_LUMINANCE, or GL_LUMINANCE_ALPHA.
GL_INVALID_ENUM is generated if glGetMinmaxEXT parameter <type> is not
GL_UNSIGNED_BYTE, GL_BYTE, GL_UNSIGNED_SHORT, GL_SHORT,
GL_UNSIGNED_INT, GL_INT, or GL_FLOAT.
GL_INVALID_ENUM is generated if glGetMinmaxParameterivEXT or glGetMin‐
maxParameterfvEXT parameter <target> is not GL_MINMAX_EXT.
GL_INVALID_ENUM is generated if glGetMinmaxParameterivEXT or glGetMin‐
maxParameterfvEXT parameter <pname> is not GL_MINMAX_FORMAT_EXT or
GL_MINMAX_SINK_EXT.
GL_INVALID_OPERATION is generated if glGetMinmaxEXT, glGetMinmaxParame‐
terivEXT, or GetMinmaxParameterfvEXT is called between execution of
glBegin and the corresponding execution of glEnd.
ASSOCIATED CALLS
glMinmaxEXT and glResetMinmaxEXT.
SEE ALSO
glHistogramEXT, glResetHistogramEXT, glGetHistogramEXT, glGetHistogram‐
ParameterivEXT, glGetHistogramParameterfvEXT, glDrawPixels, glCopyPix‐
els, glReadPixels, glTexImage2D, glTexImage3DEXT, glTexSubImage2DEXT,
glCopyTexImage2DEXT, glCopyTexSubImage2DEXT, glGetTexImage, glPixel‐
Tranferf, glPixelTransferi, glEnable, glDisable, glIsEnabled, glPixel‐
Store.
1 Dec 97 GLGETMINMAXEXT(3GL)