GLMINMAX(3G)GLMINMAX(3G)NAME
glMinmax - 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 com‐
ponent is greater than the corresponding component in the maximum ele‐
ment, 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 ini‐
tialized with the largest possible component values. The values in the
previous minmax table, if any, are lost. If sink is GL_TRUE, then pix‐
els are discarded after minmax; no further processing of the pixels
takes place, and no drawing, texture loading, or pixel readback will
result.
NOTES
glMinmax 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 val‐
ues.
GL_INVALID_ENUM is generated if internalformat is not one of the allow‐
able 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)GLMINMAX(3G)
