Contains size of rasterized points, in pixels.
In the vertex, tessellation evaluation and geometry languages, a single global instance of thegl_PerVertexnamed block is available and itsgl_PointSizemember 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_PointSizeis used to determine the size of rasterized points, otherwise it is ignored by the rasterization stage.
In the tessellation control language, thegl_PerVertexnamed block is used to construct an array,gl_out, whose members become available as inputs to the subsequent tessellation evaluation shader.
The value ofgl_PointSize(or thegl_PointSizemember of thegl_outarray, 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 writtengl_PointSizesince the last call to EmitVertex (or hasn't written it at all).
In the tessellation control, tessellation evaluation and geometry languages, thegl_PerVertexnamed block is used to construct an array,gl_inof per-vertex or per-control point inputs whose content represents the corresponding outputs written by the previous stage.
|gl_PointSize (vertex shader)||1.1+|
|gl_PointSize (geometry shader)||1.5+|
|gl_PointSize (tessellation evaluation shader)||4.0+|
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