title: Ordering of transparent ParticleSystem with BufferGeometry in Threejs
body: <p>Related to this question : <a href="https://stackoverflow.com/questions/18657444/z-buffer-issue-with-buffergeometry-in-particlesystem">Z-buffer issue with BufferGeometry in ParticleSystem</a></p>
  
  <p>The given solution does not work for me, I made my own shader for rendering as I added custom attributes for size and UV. Everythinf works fine with the buffer geometry except the particle ordering for transparency.</p>
  
  <p>If Activated > squared texture are partly hiding the other particles.</p>
  
  <p>If Deactivated (depthTest : false) > particles looks fine but are not ordered.</p>
  
  <p>Thanks for your answer, the subject has been raised several times but nothing worked for me yet.</p>
  
  <p>Using Three.js 61</p>
  
  <pre><code>            particleMaterial = new THREE.ShaderMaterial({
                      fragmentShader    : document.getElementById("sectorPointFragment").textContent,
                      vertexShader  : document.getElementById("sectorPointVertex").textContent,
                      uniforms  : uniforms,
                      attributes : attributes,
                      transparent : true,
                      alphaTest : 0.5
                  });         
  
  
              _this.particles = new THREE.ParticleSystem(geometry, particleMaterial);
  
              _this.particles.sortParticles = true;   
  </code></pre>