title: Weird shadowy diagonal lines along edge of mesh
body: <p>First, here's an example of what I am describing as "Weird shadowy diagonal lines".</p>
  
  <p><a href="https://i.stack.imgur.com/Sj38q.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Sj38q.png" alt="Example of shadowy lines"></a></p>
  
  <p>This is the top of a table constructed in Maya an exported as <code>.obj</code>. It is loaded as follows:</p>
  
  <pre><code>let mtlLoader = new THREE.MTLLoader();
  
  mtlLoader.setPath( './assets/' );
  mtlLoader.load( 'table.mtl', ( materials ) =&gt; {
  
      materials.preload();
  
      let objLoader = new THREE.OBJLoader();
      objLoader.setMaterials( materials );
      objLoader.setPath( './assets/' );
      objLoader.load( 'table.obj', ( object ) =&gt; {
          if ( child instanceof THREE.Mesh ) {
              let _color = child.material.color;
              if ( _color.r === 0 &amp;&amp; _color.g === 0 &amp;&amp; _color.b === 0 ) {
                  child.material.color.r = 0.65;
                  child.material.color.g = 0.65;
                  child.material.color.b = 0.65;
              }
              child.castShadow = true;
              child.receiveShadow = true;
              child.material.shading = THREE.FlatShading;
          }
  
          scene.add( object );
          animate();
      }
  }
  </code></pre>
  
  <p>There is only one light in this scene and here is the code that produces it.</p>
  
  <pre><code>SpotLight_1 = new THREE.SpotLight( 0xffffff, 1 );
  SpotLight_1.position.set( 60, 90, 60 );
  SpotLight_1.castShadow = true;
  SpotLight_1.shadow.mapSize.width = 2048;
  SpotLight_1.shadow.mapSize.height = 2048;
  scene.add( this.three.SpotLight_1 );
  </code></pre>
  
  <p>Here is the part that will probably make the problem apparent to someone with more experience with 3d meshes and three js than myself... If I set the <code>SpotLight_1.shadow.mapSize.width = 128</code> set the <code>mapSize.height</code> equal to 128 as well, the lines span the whole inner surface of the table. Here is a picture.</p>
  
  <p><a href="https://i.stack.imgur.com/YF8Ng.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/YF8Ng.png" alt="Example of lines spanning inner mesh"></a></p>
  
  <p>The inner mesh material type is phong, the border is lambert if this is pertinent.</p>
  
  <p>I'm assuming it has something to do with the angle of the light hitting a reflective surface. The light is @ 60 on Y-axis and the table has a collective height of 30.5. The affect is noticeable when the camera is rotated such that the table is between the light and the camera.</p>
  
  <p>Any insight would be greatly appreciated. If any additional information is needed I will be happy to provide.</p>