From ce778f47b1c6fc29999a5f9a865ba1c1514f866f Mon Sep 17 00:00:00 2001
From: Andrzej Kapolka <drzej.k@gmail.com>
Date: Fri, 20 Jun 2014 14:08:39 -0700
Subject: [PATCH] More work on stream testing, fixed bug with
 differently-ordered edits.

---
 libraries/metavoxels/src/MetavoxelData.cpp | 21 +++++++++++++++++----
 tests/metavoxels/src/MetavoxelTests.cpp    |  8 ++++----
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/libraries/metavoxels/src/MetavoxelData.cpp b/libraries/metavoxels/src/MetavoxelData.cpp
index d7528d1959..6d1031d3cf 100644
--- a/libraries/metavoxels/src/MetavoxelData.cpp
+++ b/libraries/metavoxels/src/MetavoxelData.cpp
@@ -1153,8 +1153,23 @@ int MetavoxelVisitor::encodeOrder(const glm::vec3& direction) {
         indexDistances.at(6).index, indexDistances.at(7).index);
 }
 
+const int ORDER_ELEMENT_BITS = 3;
+const int ORDER_ELEMENT_MASK = (1 << ORDER_ELEMENT_BITS) - 1;
+
 int MetavoxelVisitor::encodeRandomOrder() {
-    return DEFAULT_ORDER;
+    // see http://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle#The_.22inside-out.22_algorithm
+    int order;
+    int randomValues = rand();
+    for (int i = 0, iShift = 0; i < MetavoxelNode::CHILD_COUNT; i++, iShift += ORDER_ELEMENT_BITS) {
+        int j = (randomValues >> iShift) % (i + 1);
+        int jShift = j * ORDER_ELEMENT_BITS;
+        if (j != i) {
+            int jValue = (order >> jShift) & ORDER_ELEMENT_MASK;
+            order = (order & ~(ORDER_ELEMENT_MASK << iShift)) | (jValue << iShift);
+        }
+        order = (order & ~(ORDER_ELEMENT_MASK << jShift)) | (i << jShift);
+    }
+    return order;
 }
 
 const int MetavoxelVisitor::DEFAULT_ORDER = encodeOrder(0, 1, 2, 3, 4, 5, 6, 7);
@@ -1350,8 +1365,6 @@ bool DefaultMetavoxelGuide::guide(MetavoxelVisitation& visitation) {
             QVector<OwnedAttributeValue>(visitation.outputNodes.size()) } };
     for (int i = 0; i < MetavoxelNode::CHILD_COUNT; i++) {
         // the encoded order tells us the child indices for each iteration
-        const int ORDER_ELEMENT_BITS = 3;
-        const int ORDER_ELEMENT_MASK = (1 << ORDER_ELEMENT_BITS) - 1;
         int index = encodedOrder & ORDER_ELEMENT_MASK;
         encodedOrder >>= ORDER_ELEMENT_BITS;
         for (int j = 0; j < visitation.inputNodes.size(); j++) {
@@ -1392,7 +1405,7 @@ bool DefaultMetavoxelGuide::guide(MetavoxelVisitation& visitation) {
                 }
             }
             MetavoxelNode* node = visitation.outputNodes.at(j);
-            MetavoxelNode* child = node->getChild(i);
+            MetavoxelNode* child = node->getChild(index);
             if (child) {
                 child->decrementReferenceCount(value.getAttribute());
             } else {
diff --git a/tests/metavoxels/src/MetavoxelTests.cpp b/tests/metavoxels/src/MetavoxelTests.cpp
index d261d9d926..6aef40eab1 100644
--- a/tests/metavoxels/src/MetavoxelTests.cpp
+++ b/tests/metavoxels/src/MetavoxelTests.cpp
@@ -598,17 +598,17 @@ public:
 
 private:
     
-    bool _finished;
+    int _mutationsRemaining;
 };
 
 MutateVisitor::MutateVisitor() :
     MetavoxelVisitor(QVector<AttributePointer>(),
         QVector<AttributePointer>() << AttributeRegistry::getInstance()->getColorAttribute()),
-    _finished(false) {
+    _mutationsRemaining(randIntInRange(2, 4)) {
 }
 
 int MutateVisitor::visit(MetavoxelInfo& info) {
-    if (_finished) {
+    if (_mutationsRemaining <= 0) {
         return STOP_RECURSION;
     }
     if (info.size > MAXIMUM_LEAF_SIZE || (info.size > MINIMUM_LEAF_SIZE && randomBoolean())) {
@@ -616,7 +616,7 @@ int MutateVisitor::visit(MetavoxelInfo& info) {
     }
     info.outputValues[0] = OwnedAttributeValue(_outputs.at(0), encodeInline<QRgb>(qRgb(randIntInRange(0, 255),
         randIntInRange(0, 255), randIntInRange(0, 255))));
-    _finished = true;
+    _mutationsRemaining--;
     return STOP_RECURSION;
 }