title: OpenGL transparent images have black in them
body: <p>I am working on a game for Android and I was wondering why whenever I draw images with transparency there seems to always be some black added to the transparent parts. This happens all over and makes some of my effects look strange.</p>
  
  <p>Here is an example. The two circles are only white images with a blur but you can see when one overlaps the other it has a shadow. If I overlap two of the circles say in Inkscape I get pure white where they overlap. </p>
  
  <p><img src="https://i.stack.imgur.com/Meyib.png" alt="enter image description here"></p>
  
  <p>I am using </p>
  
  <pre><code>GLES20.glEnable(GLES20.GL_BLEND);
  GLES20.glBlendFunc(GLES20.GL_SRC_ALPHA, GLES20.GL_ONE_MINUS_SRC_ALPHA);
  </code></pre>
  
  <p>for my blending. </p>
  
  <p>Any idea why this happens and how I can avoid it?</p>
  
  <p>Edit: the only thing I can think of is that the two images have the same z so maybe they are blending only with the background instead of each other?</p>
  
  <p>Edit: 
  I changed</p>
  
  <pre><code>GLES20.glBlendFunc(GLES20.GL_SRC_ALPHA, GLES20.GL_ONE_MINUS_SRC_ALPHA);
  </code></pre>
  
  <p>to</p>
  
  <pre><code>GLES20.glBlendFunc(GLES20.GL_SRC_ALPHA, GLES20.GL_DST_ALPHA);
  </code></pre>
  
  <p>Here is the result I was looking for.</p>
  
  <p><img src="https://i.stack.imgur.com/GIJd5.png" alt="enter image description here"></p>
  
  <p>The only thing now is that the transparent images that I had that have a transparent black in them are ignored, which makes sense because I think the destination alpha is 1. Why would One minus source add that gray?</p>