gl.PointSize(size)
gl.PointSize()
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 gl.Enable() and gl.Disable() with argument #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 + 0.5, yw + 0.5) |
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 + 0.5, yw + 0.5) |
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 non-antialiased 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 (xw,yw). The coverage value for each fragment is the window 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 implementation. To query the range of
supported sizes and the size difference between supported sizes within the range, call gl.Get() with
arguments #GL_POINT_SIZE_RANGE
and #GL_POINT_SIZE_GRANULARITY
.
The point size specified by gl.PointSize()
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-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.
Please consult an OpenGL reference manual for more information.
#GL_INVALID_VALUE
is generated if size is less than or equal to 0.
#GL_INVALID_OPERATION
is generated if gl.PointSize()
is executed between the execution of gl.Begin() and the corresponding execution of gl.End().
#GL_POINT_SIZE
gl.Get() with argument #GL_POINT_SIZE_RANGE
gl.Get() with argument #GL_POINT_SIZE_GRANULARITY
gl.IsEnabled() with argument #GL_POINT_SMOOTH