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GLPOINTSIZE()							 GLPOINTSIZE()

NAME
       glPointSize - specify the diameter of rasterized	points

C SPECIFICATION
       void glPointSize( GLfloat size )

       delim $$

PARAMETERS
       size  Specifies	the  diameter of rasterized points.  The initial value
	     is	1.

DESCRIPTION
       glPointSize specifies the rasterized diameter of	both aliased  and  an-
       tialiased  points.   Using  a point size	other than 1 has different ef-
       fects, depending	on whether point antialiasing is enabled.   To	enable
       and  disable point antialiasing,	call glEnable and glDisable with argu-
       ment GL_POINT_SMOOTH. Point antialiasing	is initially disabled.

       If point	antialiasing is	disabled, the actual  size  is	determined  by
       rounding	 the  supplied	size to	the nearest integer.  (If the rounding
       results in the value 0, it is as	if the point size  were	 1.)   If  the
       rounded	size is	odd, then the center point ($ x	$, $ y $) of the pixel
       fragment	that represents	the point is computed as

	    ( $	|_ ~ x sub w ~ _| ~+~ .5 $, $ |_ ~ y sub w ~ _|	~+~ .5 $)

       where $w$ subscripts indicate window coordinates.  All pixels that  lie
       within  the  square grid	of the rounded size centered at	($ x $,	$ y $)
       make up the fragment.  If the size is even, the center point is

	    ( $	|_ ~ x sub w ~+~ .5 ~ _|$, $ |_	~ y sub	w ~+~ .5 ~ _| $)

       and the rasterized fragment's centers are the half-integer window coor-
       dinates	within	the square of the rounded size centered	at ($ x	$, $ y
       $).  All	pixel fragments	produced in rasterizing	a nonantialiased point
       are assigned the	same associated	data, that of the vertex corresponding
       to the point.

       If antialiasing is enabled, then	point rasterization produces  a	 frag-
       ment  for each pixel square that	intersects the region lying within the
       circle having diameter equal to the current point size and centered  at
       the  point's  ($	 x sub w $, $ y	sub w $).  The coverage	value for each
       fragment	is the window coordinate area of the intersection of the  cir-
       cular  region with the corresponding pixel square.  This	value is saved
       and used	in the final rasterization step.   The	data  associated  with
       each fragment is	the data associated with the point being rasterized.

       Not  all	sizes are supported when point antialiasing is enabled.	 If an
       unsupported size	is requested, the  nearest  supported  size  is	 used.
       Only  size 1 is guaranteed to be	supported; others depend on the	imple-
       mentation.  To query the	range of supported sizes and the size  differ-
       ence  between  supported	 sizes within the range, call glGet with argu-
       ments GL_POINT_SIZE_RANGE and GL_POINT_SIZE_GRANULARITY.

NOTES
       The point  size	specified  by  glPointSize  is	always	returned  when
       GL_POINT_SIZE  is  queried.   Clamping and rounding for aliased and an-
       tialiased points	have no	effect on the specified	value.

       A non-antialiased point size may	be clamped to an implementation-depen-
       dent  maximum.	Although this maximum cannot be	queried, it must be no
       less than the maximum value for	antialiased  points,  rounded  to  the
       nearest integer value.

ERRORS
       GL_INVALID_VALUE	is generated if	size is	less than or equal to 0.

       GL_INVALID_OPERATION  is	 generated  if glPointSize is executed between
       the execution of	glBegin	and the	corresponding execution	of glEnd.

ASSOCIATED GETS
       glGet with argument GL_POINT_SIZE
       glGet with argument GL_POINT_SIZE_RANGE
       glGet with argument GL_POINT_SIZE_GRANULARITY
       glIsEnabled with	argument GL_POINT_SMOOTH

SEE ALSO
       glEnable

								 GLPOINTSIZE()

NAME | C SPECIFICATION | PARAMETERS | DESCRIPTION | NOTES | ERRORS | ASSOCIATED GETS | SEE ALSO

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