Add Transform.isIdentity().

src/main/java/com/sk89q/worldedit/math/transform/AffineTransform.java

@@ -109,6 +109,7 @@ public class AffineTransform implements Transform {
     // ===================================================================
     // accessors
 
+    @Override
     public boolean isIdentity() {
         if (m00 != 1)
             return false;

src/main/java/com/sk89q/worldedit/math/transform/CombinedTransform.java

@@ -54,6 +54,17 @@ public class CombinedTransform implements Transform {
         this(transforms.toArray(new Transform[checkNotNull(transforms).size()]));
     }
 
+    @Override
+    public boolean isIdentity() {
+        for (Transform transform : transforms) {
+            if (!transform.isIdentity()) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     @Override
     public Vector apply(Vector vector) {
         for (Transform transform : transforms) {

src/main/java/com/sk89q/worldedit/math/transform/Identity.java

@@ -26,6 +26,11 @@ import com.sk89q.worldedit.Vector;
  */
 public class Identity implements Transform {
 
+    @Override
+    public boolean isIdentity() {
+        return true;
+    }
+
     @Override
     public Vector apply(Vector vector) {
         return vector;

src/main/java/com/sk89q/worldedit/math/transform/Transform.java

@@ -26,6 +26,15 @@ import com.sk89q.worldedit.Vector;
  */
 public interface Transform {
 
+    /**
+     * Return whether this transform is an identity.
+     *
+     * <p>If it is not known, then {@code false} must be returned.</p>
+     *
+     * @return true if identity
+     */
+    boolean isIdentity();
+
     /**
      * Returns the result of applying the function to the input.
      *