The point size specified by glPointSize is always returned when GL_POINT_SIZE is queried. The range of supported sizes and the size difference between supported sizes within the range can be queried by calling glGet with arguments GL_POINT_SIZE_RANGE and GL_POINT_SIZE_GRANULARITY. Only size 1.0 is guaranteed to be supported others depend on the implementation. If an unsupported size is requested, the nearest supported size is used. Not all sizes are supported when point antialiasing is enabled. The data associated with each fragment is the data associated with the point being rasterized. This value is saved and used in the final rasterization step. The coverage value for each fragment is the window coordinate area of the intersection of the circular region with the corresponding pixel square. 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 points ( x w, y w ). All pixel fragments produced in rasterizing a nonantialiased point are assigned the same associated data that of the vertex corresponding to the point. If the size is even, the center point isĪnd the rasterized fragment's centers are the half-integer window coordinates within the square of the rounded size centered at ( x, y). All pixels that lie within the square grid of the rounded size centered at ( x, y) make up the fragment. Where w subscripts indicate window coordinates. (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 If point antialiasing is disabled, the actual size is determined by rounding the supplied size to the nearest integer. Point antialiasing is controlled by calling glEnable and glDisable with argument GL_POINT_SMOOTH.
Using a point size other than 1.0 has different effects, depending on whether point antialiasing is enabled. The glPointSize function specifies the rasterized diameter of both aliased and antialiased points. The function was called between a call to glBegin and the corresponding call to glEnd. The following error codes can be retrieved by the glGetError function.
The glPointSize function specifies the diameter of rasterized points.
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