Add Viewer.forwardRay()

docs/api/viewer.md

 **Returns**
 
 A ray in world space that corresponds to the given point.
+
+### forwardRay
+
+`viewer.forwardRay(): Ray`
+
+Compute a [ray](ray.md) in the forward direction from the viewer.
+
+*Since:* 0.4.0
+
+**Returns**
+
+A new ray in world space.

src/geometry/viewer.ts

 
         return new Ray(origin, direction);
     }
+
+    /**
+     * Compute a ray in the forward direction from the viewer
+     * @returns a new ray in world space
+     */
+    forwardRay(): Ray
+    {
+        const origin = this._pose.transform.position;
+        const direction = this._pose.transform.forward;
+
+        return new Ray(origin, direction);
+    }
 }