computers can be a complicated topic. There are various
solutions and all of them have tradeoffs including the solutions
available in three.js.</p>
<p>Three.js by default uses <em>shadow maps</em>. The way a shadow map works
is, <em>for every light that casts shadows all objects marked to cast
shadows are rendered from the point of view of the light</em>. <strong>READ THAT
AGAIN!</strong> and let it sink in.</p>
<p>In other words, if you have 20 objects, and 5 lights, and
all 20 objects are casting shadows 