gl_PointSize.3G man page

gl_PointSize — contains size of rasterized points, in pixels


gl_PointSize is a member of the gl_PerVertex named block:

out gl_PerVertex {
    vec4 gl_Position;
    float gl_PointSize;
    float gl_ClipDistance[];


In the vertex, tessellation evaluation and geometry languages, a single global instance of the gl_PerVertex named block is available and its gl_PointSize member is an output that receives the intended size of the point to be rasterized, in pixels. It may be written at any time during shader execution. If GL_PROGRAM_POINT_SIZE is enabled, gl_PointSize is used to determine the size of rasterized points, otherwise it is ignored by the rasterization stage.

In the tessellation control language, the gl_PerVertex named block is used to construct an array, gl_out[], whose members become available as inputs to the subsequent tessellation evaluation shader.

The value of gl_PointSize (or the gl_PointSize member of the gl_out[] array, in the case of the tessellation control shader) is undefined after the vertex, tessellation control, and tessellation evaluation shading stages if the corresponding shader executable does not write to gl_PointSize. It is also undefined after the geometry processing stage if the geometry shader executable calls EmitVertex() without having written gl_PointSize since the last call to EmitVertex() (or hasn't written it at all).

In the tessellation control, tessellation evaluation and geometry languages, the gl_PerVertex named block is used to construct an array, gl_in[] of per-vertex or per-control point inputs whose content represents the corresponding outputs written by the previous stage.

Version Support

gl_PointSize (vertex shader)
gl_PointSize (geometry shader)
gl_PointSize (tessellation evaluation shader)

See Also

gl_Position(), gl_ClipDistance()