From edfd5cd5439324febd7b5802330d50091e02a0ad Mon Sep 17 00:00:00 2001
From: ZappoMan <bradh@konamoxt.com>
Date: Mon, 5 Aug 2013 09:45:00 -0700
Subject: [PATCH] fixed disappearing voxel bug

---
 interface/src/VoxelSystem.cpp | 29 +++++++++++++++++++++++------
 interface/src/VoxelSystem.h   |  1 +
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/interface/src/VoxelSystem.cpp b/interface/src/VoxelSystem.cpp
index 2631e255fb..fbc6760665 100644
--- a/interface/src/VoxelSystem.cpp
+++ b/interface/src/VoxelSystem.cpp
@@ -73,10 +73,29 @@ void VoxelSystem::nodeDeleted(VoxelNode* node) {
     }
 }
 
+// returns an available index, starts by reusing a previously freed index, but if there isn't one available
+// it will use the end of the VBO array and grow our accounting of that array.
+// and makes the index available for some other node to use
+glBufferIndex VoxelSystem::getNextBufferIndex() {
+    glBufferIndex output = GLBUFFER_INDEX_UNKNOWN;
+    // if there's a free index, use it...
+    if (_freeIndexes.size() > 0) {
+        output = _freeIndexes.back();
+        _freeIndexes.pop_back();
+    } else {
+        output = _voxelsInWriteArrays;
+        _voxelsInWriteArrays++;
+    }
+    return output;
+}
+
+// Doesn't actually clean up the VBOs for the index, but does release responsibility of the index from the VoxelNode, 
+// and makes the index available for some other node to use
 void VoxelSystem::freeBufferIndex(glBufferIndex index) {
     _freeIndexes.push_back(index);
 }
 
+// This will run through the list of _freeIndexes and reset their VBO array values to be "invisible".
 void VoxelSystem::clearFreeBufferIndexes() {
     for (int i = 0; i < _freeIndexes.size(); i++) {
         glBufferIndex nodeIndex = _freeIndexes[i];
@@ -246,12 +265,13 @@ void VoxelSystem::setupNewVoxelsForDrawing() {
         _callsToTreesToArrays++;
         if (_writeRenderFullVBO) {
             _voxelsInWriteArrays = 0; // reset our VBO
+            _freeIndexes.clear(); // reset our free indexes
         }
         _voxelsUpdated = newTreeToArrays(_tree->rootNode);
         _tree->clearDirtyBit(); // after we pull the trees into the array, we can consider the tree clean
 
         if (_writeRenderFullVBO) {
-            _abandonedVBOSlots = 0; // reset the count of our abandoned slots
+            _abandonedVBOSlots = 0; // reset the count of our abandoned slots, why is this here and not earlier????
         }
         
         // since we called treeToArrays, we can assume that our VBO is in sync, and so partial updates to the VBOs are
@@ -399,15 +419,13 @@ int VoxelSystem::updateNodeInArraysAsFullVBO(VoxelNode* node) {
     if (node->getShouldRender()) {
         glm::vec3 startVertex = node->getCorner();
         float voxelScale = node->getScale();
-        glBufferIndex nodeIndex = _voxelsInWriteArrays;
+        glBufferIndex nodeIndex = getNextBufferIndex();
 
         // populate the array with points for the 8 vertices
         // and RGB color for each added vertex
         updateNodeInArrays(nodeIndex, startVertex, voxelScale, node->getColor());
         node->setBufferIndex(nodeIndex);
         node->setVoxelSystem(this);
-        _writeVoxelDirtyArray[nodeIndex] = true; // just in case we switch to Partial mode
-        _voxelsInWriteArrays++; // our know vertices in the arrays
         return 1; // rendered
     } else {
         node->setBufferIndex(GLBUFFER_INDEX_UNKNOWN);
@@ -444,10 +462,9 @@ int VoxelSystem::updateNodeInArraysAsPartialVBO(VoxelNode* node) {
         if (node->isKnownBufferIndex()) {
             nodeIndex = node->getBufferIndex();
         } else {
-            nodeIndex = _voxelsInWriteArrays;
+            nodeIndex = getNextBufferIndex();
             node->setBufferIndex(nodeIndex);
             node->setVoxelSystem(this);
-            _voxelsInWriteArrays++;
         }
         _writeVoxelDirtyArray[nodeIndex] = true;
 
diff --git a/interface/src/VoxelSystem.h b/interface/src/VoxelSystem.h
index ef7c33ee43..6c6bf261f9 100644
--- a/interface/src/VoxelSystem.h
+++ b/interface/src/VoxelSystem.h
@@ -200,6 +200,7 @@ private:
 
     void freeBufferIndex(glBufferIndex index);
     void clearFreeBufferIndexes();
+    glBufferIndex getNextBufferIndex();
     
     bool _falseColorizeBySource;
     int  _dataSourceID;