glPointSize(3G)		       OpenGL Reference		       glPointSize(3G)



NAME
     glPointSize - specify the diameter	of rasterized points


C SPECIFICATION
     void glPointSize( GLfloat size )


PARAMETERS
     size  Specifies the diameter of rasterized	points.	 The default is	1.0.


DESCRIPTION
     glPointSize specifies the rasterized diameter of both aliased and
     antialiased points.  Using	a point	size other than	1.0 has	different
     effects, depending	on whether point antialiasing is enabled.  Point
     antialiasing is controlled	by calling glEnable and	glDisable with
     argument GL_POINT_SMOOTH.

     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  |+.5, | y	|+.5)
				   w	      w
     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 +.5	|, | y +.5 |)
				   w	      w
     and the rasterized	fragment's centers are the half-integer	window
     coordinates 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 fragment
     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	, y ).	The coverage value for each fragment is	the window
     coordinatewarea of	the intersection of the	circular 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 1.0 is guaranteed to be supported; others depend on the
     implementation.  The range	of supported sizes and the size	difference



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glPointSize(3G)		       OpenGL Reference		       glPointSize(3G)



     between supported sizes within the	range can be queried by	 calling glGet
     with arguments 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
     antialiased points	have no	effect on the specified	value.

     Non-antialiased point size	may be clamped to an implementation-dependent
     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 zero.

     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


























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