Vec3Arg: add the swizzle() method

src/main/java/com/github/stephengold/joltjni/Vec3.java

@@ -602,6 +602,28 @@ public void storeFloat3(Float3 target) {
         target.z = z;
     }
 
+    /**
+     * Copy the specified components to a new vector. The current vector is
+     * unaffected.
+     *
+     * @param xi index of the component to copy to the first (X) component of
+     * the result (0, 1, or 2)
+     * @param yi index of the component to copy to the 2nd (Y) component of the
+     * result (0, 1, or 2)
+     * @param zi index of the component to copy to the 3rd (Z) component of the
+     * result (0, 1, or 2)
+     * @return the new vector
+     */
+    @Override
+    public Vec3 swizzle(int xi, int yi, int zi) {
+        float rx = get(xi);
+        float ry = get(yi);
+        float rz = get(zi);
+        Vec3 result = new Vec3(rx, ry, rz);
+
+        return result;
+    }
+
     /**
      * Copy the components to an array. The vector is unaffected.
      *

src/main/java/com/github/stephengold/joltjni/readonly/Vec3Arg.java

@@ -176,6 +176,20 @@ public interface Vec3Arg {
      */
     void storeFloat3(Float3 target);
 
+    /**
+     * Copy the specified components to a new vector. The current vector is
+     * unaffected.
+     *
+     * @param xi index of the component to copy to the first (X) component of
+     * the result (0, 1, or 2)
+     * @param yi index of the component to copy to the 2nd (Y) component of the
+     * result (0, 1, or 2)
+     * @param zi index of the component to copy to the 3rd (Z) component of the
+     * result (0, 1, or 2)
+     * @return the new vector
+     */
+    Vec3 swizzle(int xi, int yi, int zi);
+
     /**
      * Copy the components to an array. The vector is unaffected.
      *