From 87cc565c1ac7105c12880be1d21f49b3cea31dc7 Mon Sep 17 00:00:00 2001
From: Andrzej Kapolka <drzej.k@gmail.com>
Date: Thu, 20 Nov 2014 18:16:57 -0800
Subject: [PATCH] I believe this should be a better hash function for the voxel
 coordinates.

---
 interface/src/MetavoxelSystem.cpp |  6 +++---
 interface/src/MetavoxelSystem.h   | 19 +++++++++++++++++--
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/interface/src/MetavoxelSystem.cpp b/interface/src/MetavoxelSystem.cpp
index 7129ac4e88..b0a5d3324c 100644
--- a/interface/src/MetavoxelSystem.cpp
+++ b/interface/src/MetavoxelSystem.cpp
@@ -1011,7 +1011,7 @@ void VoxelPoint::setNormal(const glm::vec3& normal) {
 }
 
 VoxelBuffer::VoxelBuffer(const QVector<VoxelPoint>& vertices, const QVector<int>& indices, const QVector<glm::vec3>& hermite,
-        const QMultiHash<QRgb, int>& quadIndices, int size, const QVector<SharedObjectPointer>& materials) :
+        const QMultiHash<VoxelCoord, int>& quadIndices, int size, const QVector<SharedObjectPointer>& materials) :
     _vertices(vertices),
     _indices(indices),
     _hermite(hermite),
@@ -1056,7 +1056,7 @@ bool VoxelBuffer::findFirstRayIntersection(const glm::vec3& entry, const glm::ve
     int max = _size - 2;
     int x = qMin((int)floors.x, max), y = qMin((int)floors.y, max), z = qMin((int)floors.z, max);
     forever {
-        for (QMultiHash<QRgb, int>::const_iterator it = _quadIndices.constFind(qRgb(x + 1, y + 1, z + 1));
+        for (QMultiHash<VoxelCoord, int>::const_iterator it = _quadIndices.constFind(qRgb(x + 1, y + 1, z + 1));
                 it != _quadIndices.constEnd(); it++) {
             const int* indices = _indices.constData() + *it;
             if (findRayTriangleIntersection(origin, direction, _vertices.at(indices[0]).vertex,
@@ -1311,7 +1311,7 @@ int VoxelAugmentVisitor::visit(MetavoxelInfo& info) {
         QVector<VoxelPoint> vertices;
         QVector<int> indices;
         QVector<glm::vec3> hermiteSegments;
-        QMultiHash<QRgb, int> quadIndices;
+        QMultiHash<VoxelCoord, int> quadIndices;
         
         // see http://www.frankpetterson.com/publications/dualcontour/dualcontour.pdf for a description of the
         // dual contour algorithm for generating meshes from voxel data using Hermite-tagged edges
diff --git a/interface/src/MetavoxelSystem.h b/interface/src/MetavoxelSystem.h
index 90a04ae417..dfbabbb2bf 100644
--- a/interface/src/MetavoxelSystem.h
+++ b/interface/src/MetavoxelSystem.h
@@ -308,12 +308,27 @@ public:
     void setNormal(const glm::vec3& normal);
 };
 
+/// A container for a coordinate within a voxel block.
+class VoxelCoord {
+public:
+    QRgb encoded;
+    
+    VoxelCoord(QRgb encoded) : encoded(encoded) { }
+    
+    bool operator==(const VoxelCoord& other) const { return encoded == other.encoded; }
+};
+
+inline uint qHash(const VoxelCoord& coord, uint seed) {
+    // 31 is just an arbitrary prime number
+    return qHash(qRed(coord.encoded) + 31 * (qGreen(coord.encoded) + 31 * qBlue(coord.encoded)), seed);
+}
+
 /// Contains the information necessary to render a voxel block.
 class VoxelBuffer : public BufferData {
 public:
     
     VoxelBuffer(const QVector<VoxelPoint>& vertices, const QVector<int>& indices, const QVector<glm::vec3>& hermite,
-        const QMultiHash<QRgb, int>& quadIndices, int size, const QVector<SharedObjectPointer>& materials =
+        const QMultiHash<VoxelCoord, int>& quadIndices, int size, const QVector<SharedObjectPointer>& materials =
             QVector<SharedObjectPointer>());
 
     /// Finds the first intersection between the described ray and the voxel data.
@@ -328,7 +343,7 @@ private:
     QVector<VoxelPoint> _vertices;
     QVector<int> _indices;
     QVector<glm::vec3> _hermite;
-    QMultiHash<QRgb, int> _quadIndices;
+    QMultiHash<VoxelCoord, int> _quadIndices;
     int _size;
     int _vertexCount;
     int _indexCount;