Initial commit

BlueNoise/WeightedDiscretePDF.h

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+// $Id: WeightedDiscretePDF.h,v 1.4 2006/07/07 05:54:31 zr Exp $
+
+template <class T>
+class WDPDF_Node
+{
+private:
+	bool m_mark;
+
+public:
+	WDPDF_Node<T> *parent, *left, *right;
+	T key;
+	float weight, sumWeights;
+
+public:
+	WDPDF_Node(T key_, float weight_, WDPDF_Node<T> *parent_);
+	~WDPDF_Node();
+
+	WDPDF_Node<T> *sibling() { return this==parent->left?parent->right:parent->left; }
+
+	void markRed() { m_mark = true; }
+	void markBlack() { m_mark = false; }
+	bool isRed() { return m_mark; }
+	bool isBlack() { return !m_mark; }
+	bool leftIsBlack() { return !left || left->isBlack(); }
+	bool rightIsBlack() { return !right || right->isBlack(); }
+	bool leftIsRed() { return !leftIsBlack(); }
+	bool rightIsRed() { return !rightIsBlack(); }
+	void setSum() { sumWeights = weight + (left?left->sumWeights:0) + (right?right->sumWeights:0); }
+};
+
+template <class T>
+class WeightedDiscretePDF
+{
+private:
+	WDPDF_Node<T> *m_root;
+
+public:
+	WeightedDiscretePDF();
+	~WeightedDiscretePDF();
+
+	void insert(T item, float weight);
+	void update(T item, float newWeight);
+	void remove(T item);
+	bool inTree(T item);
+	
+		/* pick a tree element according to its
+		 * weight. p should be in [0,1).
+		 */
+	T choose(float p);
+
+private:
+	WDPDF_Node<T> **lookup(T item, WDPDF_Node<T> **parent_out);
+	void split(WDPDF_Node<T> *node);
+	void rotate(WDPDF_Node<T> *node);
+	void lengthen(WDPDF_Node<T> *node);
+	void propogateSumsUp(WDPDF_Node<T> *n);
+};