title: Shader - Color blending
body: <p>I would like to know how to blend colors in a specific way.</p>
  
  <p>Let's imagine that I have a color <strong>(A)</strong> and an other color <strong>(B)</strong>.</p>
  
  <p>I would like to blend them in such a way that if I choose white for the <strong>(B)</strong> then the output color is <strong>(A)</strong> but if have any other color for <strong>(B)</strong> it outputs a blending of <strong>(A)</strong> and <strong>(B)</strong>.</p>
  
  <ul>
  <li>I've tried the addition, but it doesn't give the expected result.</li>
  <li>I've tried the multiplicative blending it's quite good for the <strong>(B)</strong> white value but it fail for a blue <strong>(B)</strong> and red <strong>(A)</strong> colors.</li>
  </ul>
  
  <p>Any idea how to do that ?</p>