       showRadius :
         type : "i"
         value : 1
+      devicePixelRatio :
+        type : "f"
+        value : window.devicePixelRatio || 1
 
     attributes =
       size :

      uniform float baseVoxel;
      uniform float minParticleSize;
      uniform int   showRadius;
      varying vec3 vColor;
      attribute float size;


          vColor = color;
          if (showRadius == 1)
            gl_PointSize = max(
              size / zoomFactor / baseVoxel,
              minParticleSize ) * devicePixelRatio;
          else
            gl_PointSize = minParticleSize;
          gl_Position = projectionMatrix * mvPosition;
