emulate GL_POINT_SMOOTH in point shader

Author: nschimme

src/opengl/legacy/impl_gl20.cpp

@@ -60,25 +60,20 @@ bool Functions::tryEnableMultisampling(const int requestedSamples)
     if (hasMultisampling && requestedSamples > 0) {
         Base::glEnable(GL_MULTISAMPLE);
 
-        //Base::glEnable(GL_POINT_SMOOTH);
         Base::glEnable(GL_LINE_SMOOTH);
         Base::glDisable(GL_POLYGON_SMOOTH);
-        //Base::glHint(GL_POINT_SMOOTH_HINT, GL_NICEST);
         Base::glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
 
         return true;
     } else {
         // NOTE: Currently we can use OpenGL 2.1 to fake multisampling with point/line/polygon smoothing.
         // TODO: We can use OpenGL 3.x FBOs to do multisampling even if the default framebuffer doesn't support it.
         if (requestedSamples > 0) {
-            //Base::glEnable(GL_POINT_SMOOTH);
             Base::glEnable(GL_LINE_SMOOTH);
             Base::glDisable(GL_POLYGON_SMOOTH);
-            //Base::glHint(GL_POINT_SMOOTH_HINT, GL_NICEST);
             Base::glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
             return true;
         } else {
-            //Base::glDisable(GL_POINT_SMOOTH);
             Base::glDisable(GL_LINE_SMOOTH);
             Base::glDisable(GL_POLYGON_SMOOTH);
             return false;

src/resources/shaders/legacy/point/frag.glsl

@@ -9,5 +9,8 @@ out vec4 vFragmentColor;
 
 void main()
 {
+    if (dot(gl_PointCoord-0.5, gl_PointCoord-0.5) > 0.25) {
+        discard;
+    }
     vFragmentColor = vColor * uColor;
 }