CSG Intersection

### 3.3.3 CSG Intersection

Now let's use these same spheres to illustrate the next kind of CSG object, the `intersection`. We change the word `union` to `intersection` and delete the `scale` and `rotate` statements:

      intersection {
        sphere { <0, 0, 0>, 1
          translate -0.5*x
        }
        sphere { <0, 0, 0>, 1
          translate 0.5*x
        }
        pigment { Red }
      }

We trace the file and will see a lens-shaped object instead of the two spheres. This is because an intersection consists of the area shared by both shapes, in this case the lens-shaped area where the two spheres overlap. We like this lens-shaped object so we will use it to demonstrate differences.