Simplify constructors and improve constants

src/engine/Camera.java

@@ -15,9 +15,10 @@ public class Camera {
   private static final double VERTEX_VALUE_THRESHOLD = 1;
   private static final double CAMERA_MOVE_INCREMENT = -0.1;
   private static final int SAMPLE_RENDER_SAMPLES = 50;
+  private static final double EPSILON = 0.001;
+
+  private final double focalLength;
 
-  private double focalLength;
-  private double clipping = 0.001;
   private Vector3 pos;
 
   public Camera(double focalLength, Vector3 pos) {
@@ -100,7 +101,7 @@ public class Camera {
   }
 
   private Vector2 project(Vector3 vertex) {
-    if (vertex.getZ() - pos.getZ() < clipping) {
+    if (vertex.getZ() - pos.getZ() < EPSILON) {
       return new Vector2();
     }
 

src/engine/Vector3.java

@@ -6,18 +6,20 @@ public final class Vector3 {
 
   private final double x, y, z;
 
-  public Vector3() {
-    this.x = 0;
-    this.y = 0;
-    this.z = 0;
-  }
-
   public Vector3(double x, double y, double z) {
     this.x = x;
     this.y = y;
     this.z = z;
   }
 
+  public Vector3(double xyz) {
+    this(xyz, xyz, xyz);
+  }
+
+  public Vector3() {
+    this(0, 0, 0);
+  }
+
   public double getX() {
     return x;
   }