1 files changed, 121 insertions, 0 deletions
diff --git a/engine/src/core/com/jme3/renderer/IDList.java b/engine/src/core/com/jme3/renderer/IDList.java
new file mode 100644
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+++ b/engine/src/core/com/jme3/renderer/IDList.java
@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2009-2010 jMonkeyEngine
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
+ *   may be used to endorse or promote products derived from this software
+ *   without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package com.jme3.renderer;
+
+import java.util.Arrays;
+
+/**
+ * A specialized data-structure used to optimize state changes of "slot"
+ * based state. 
+ */
+public class IDList {
+
+    public int[] newList = new int[16];
+    public int[] oldList = new int[16];
+    public int newLen = 0;
+    public int oldLen = 0;
+
+    /**
+     * Reset all states to zero
+     */
+    public void reset(){
+        newLen = 0;
+        oldLen = 0;
+        Arrays.fill(newList, 0);
+        Arrays.fill(oldList, 0);
+    }
+
+    /**
+     * Adds an index to the new list.
+     * If the index was not in the old list, false is returned,
+     * if the index was in the old list, it is removed from the old
+     * list and true is returned.
+     * 
+     * @param idx The index to move
+     * @return True if it existed in old list and was removed
+     * from there, false otherwise.
+     */
+    public boolean moveToNew(int idx){
+        if (newLen == 0 || newList[newLen-1] != idx)
+            // add item to newList first
+            newList[newLen++] = idx;
+
+        // find idx in oldList, if removed successfuly, return true.
+        for (int i = 0; i < oldLen; i++){
+            if (oldList[i] == idx){
+                // found index in slot i
+                // delete index from old list
+                oldLen --;
+                for (int j = i; j < oldLen; j++){
+                    oldList[j] = oldList[j+1];
+                }
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Copies the new list to the old list, and clears the new list.
+     */
+    public void copyNewToOld(){
+        System.arraycopy(newList, 0, oldList, 0, newLen);
+        oldLen = newLen;
+        newLen = 0;
+    }
+
+    /**
+     * Prints the contents of the lists
+     */
+    public void print(){
+        if (newLen > 0){
+            System.out.print("New List: ");
+            for (int i = 0; i < newLen; i++){
+                if (i == newLen -1)
+                    System.out.println(newList[i]);
+                else
+                    System.out.print(newList[i]+", ");
+            }
+        }
+        if (oldLen > 0){
+            System.out.print("Old List: ");
+            for (int i = 0; i < oldLen; i++){
+                if (i == oldLen -1)
+                    System.out.println(oldList[i]);
+                else
+                    System.out.print(oldList[i]+", ");
+            }
+        }
+    }
+
+}