title: How to get color (r, g, b ,a) of every pixel in Three.js
body: <p>I'm using Particle to draw irregular shapes in Three.js, the code snippet is like:</p>
  
  <pre><code>var hearts = function(context){
  
  context.globalAlpha = 0.5;
  var x = 0, y = 0;
  context.scale(0.1, -0.1); // Scale so canvas render can redraw within bounds
  context.beginPath();
  context.bezierCurveTo(x + 2.5, y + 2.5, x + 2.0, y, x, y);
  context.bezierCurveTo(x - 3.0, y, x - 3.0, y + 3.5, x - 3.0, y + 3.5);
  ...
  context.closePath();
  context.lineWidth = 0.1; //0.05
  context.stroke();
  }
  
  var material = new THREE.ParticleCanvasMaterial({
  
  program: heart,
  blending: THREE.AdditiveBlending
  });
  
   material.color.setRGB(255, 0, 0);  
   var particle = new THREE.Particle(material);
  </code></pre>
  
  <p>what I want to do is select the irregular shape properly, my question is, if I draw shape this way, how can I get the color of every pixel so I can used in the picking algorithm </p>
  
  <p>Thanks.</p>