GLMINMAX(3G)GLMINMAX(3G)NAMEglMinmax - define minmax table
C SPECIFICATION
void glMinmax( GLenum target,
GLenum internalformat,
GLboolean sink )
PARAMETERS
target The minmax table whose parameters are to be set. Must be
GL_MINMAX.
internalformat
The of entries in the minmax table. Must be one of GL_ALPHA,
GL_ALPHA4, GL_ALPHA8, GL_ALPHA12, GL_ALPHA16, GL_LUMINANCE,
GL_LUMINANCE4, GL_LUMINANCE8, GL_LUMINANCE12, GL_LUMINANCE16,
GL_LUMINANCE_ALPHA, GL_LUMINANCE4_ALPHA4, GL_LUMINANCE6_ALPHA2,
GL_LUMINANCE8_ALPHA8, GL_LUMINANCE12_ALPHA4,
GL_LUMINANCE12_ALPHA12, GL_LUMINANCE16_ALPHA16, GL_R3_G3_B2,
GL_RGB, GL_RGB4, GL_RGB5, GL_RGB8, GL_RGB10, GL_RGB12, GL_RGB16,
GL_RGBA, GL_RGBA2, GL_RGBA4, GL_RGB5_A1, GL_RGBA8, GL_RGB10_A2,
GL_RGBA12, or GL_RGBA16.
sink If GL_TRUE, pixels will be consumed by the minmax process and no
drawing or texture loading will take place. If GL_FALSE, pixels
will proceed to the final conversion process after minmax.
DESCRIPTION
When GL_MINMAX is enabled, the RGBA components of incoming pixels are
compared to the minimum and maximum values for each component, which
are stored in the 2-element minmax table. (The first element stores
the minima, and the second element stores the maxima.) If a pixel
component is greater than the corresponding component in the maximum
element, then the maximum element is updated with the pixel component
value. If a pixel component is less than the corresponding component
in the minimum element, then the minimum element is updated with the
pixel component value. (In both cases, if the internal of the minmax
table includes luminance, then the R color component of incoming pixels
is used for comparison.) The contents of the minmax table may be
retrieved at a later time by calling glGetMinmax. The minmax operation
is enabled or disabled by calling glEnable or glDisable, respectively,
with an argument of GL_MINMAX.
glMinmax redefines the current minmax table to have entries of the
specified by internalformat. The maximum element is initialized with
the smallest possible component values, and the minimum element is
initialized with the largest possible component values. The values in
the previous minmax table, if any, are lost. If sink is GL_TRUE, then
pixels are discarded after minmax; no further processing of the pixels
takes place, and no drawing, texture loading, or pixel readback will
result.
NOTESglMinmax is present only if GL_ARB_imaging is returned when glGetString
is called with an argument of GL_EXTENSIONS.
ERRORS
GL_INVALID_ENUM is generated if target is not one of the allowable
values.
GL_INVALID_ENUM is generated if internalformat is not one of the
allowable values.
GL_INVALID_OPERATION is generated if glMinmax is executed between the
execution of glBegin and the corresponding execution of glEnd.
ASSOCIATED GETS
glGetMinmaxParameter
SEE ALSOglGetMinmax(3G), glResetMinmax(3G)
March 1, 2011
