gl_Position — contains the position of the current vertex
out highp vec4 gl_Position ;
gl_Position is intended for writing the homogeneous vertex position. It can be written at any time during vertexshader execution. This value will be used by primitive assembly, clipping, culling, and other fixed functionality operations, if present, that operate on primitives after vertex processing has occurred. Its value is undefined after the vertex processing stage if the vertex shader executable does not write
|OpenGL ES Shading Language Version|
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