glPointSize man page on YellowDog

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GLPOINTSIZE(3G)						       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 initial value
	     is 1.

DESCRIPTION
       glPointSize specifies the  rasterized  diameter	of  both  aliased  and
       antialiased  points.   Using  a	point  size other than 1 has different
       effects, 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

				 ( ⌊xw⌋+.5, ⌊yw⌋+.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

				 ( ⌊xw+.5⌋, ⌊yw+.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 (xw, yw).  The coverage value for each fragment is the win‐
       dow coordinate area 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 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_SMOOTH_POINT_SIZE_RANGE and  GL_SMOOTH_POINT_SIZE_GRANULARITY.
       For  aliased  points,  query  the supported ranges and granularity with
       glGet	 with	   arguments	  GL_ALIASED_POINT_SIZE_RANGE	   and
       GL_ALIASED_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.

       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.

       GL_POINT_SIZE_RANGE and GL_POINT_SIZE_GRANULARITY are deprecated in  GL
       versions	 1.2  and  greater.   Their functionality has been replaced by
       GL_SMOOTH_POINT_SIZE_RANGE and GL_SMOOTH_POINT_SIZE_GRANULARITY.

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_ALIASED_POINT_SIZE_RANGE
       glGet with argument GL_ALIASED_POINT_SIZE_GRANULARITY
       glGet with argument GL_SMOOTH_POINT_SIZE_RANGE
       glGet with argument GL_SMOOTH_POINT_SIZE_GRANULARITY
       glIsEnabled with argument GL_POINT_SMOOTH

SEE ALSO
       glEnable(3G)

							       GLPOINTSIZE(3G)
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