title: How to give smooth edges when filling a png with color in OpenGl/GLES
body: <p><img src="https://i.stack.imgur.com/lwURn.png" alt="Right one is the orginal and left one is sampled by fragment shader"></p>
  
  <p>this is my fragment shader</p>
  
  <pre><code> #ifdef GL_ES
   #define LOWP lowp
   precision mediump float;
   #else
   #define LOWP  
   #endif
   varying LOWP vec4 v_color;
   varying vec2 v_texCoords;
   uniform sampler2D u_texture;
   void main()
   {
          vec4 final_color = v_color * texture2D(u_texture, v_texCoords);
     if (final_color.w != 0.0){
                  final_color = v_color;
     }
  
     gl_FragColor = final_color;
   }
  </code></pre>