   // custom point size
   float finalPointSize = pointSize * (1. + (easedMix * (dv.r * 4.)));
 
-  // use custom vertex instead of original (vertex)
+  // use custom vertex instead of Processing default (`vertex` uniform)
+  // Processing default shader positioning:
   vec4 pos = modelview * mixedVert;
   vec4 clip = projection * pos;
 
+  // Processing default shader positioning:
   if (0 < perspective) {
     // Perspective correction (points will look thiner as they move away
     // from the view position).

/*
  Part of the Processing project - http://processing.org

  Copyright (c) 2011-13 Ben Fry and Casey Reas


    gl_Position = clip + offset;
  }

  // use original vertex color
  // vertColor = color;

  // use texture-mapped color
  vertColor = dv;
}
