ConvexHull.hpp

/*
 * ConvexHull.hpp
 *
 *  Created on: Sep 19, 2015
 *      Author: anttiku
 */

#ifndef CONVEXHULL_HPP_
#define CONVEXHULL_HPP_

#include "Structs/Vector3.hpp"
#include "Structs/Mesh.hpp"
#include "Structs/VertexDataSource.hpp"
#include <vector>
#include <unordered_map>
#include <fstream>
#include <memory>

namespace quickhull {

	template<typename T>
	class ConvexHull {
		std::unique_ptr<std::vector<Vector3<T>>> m_optimizedVertexBuffer;
		VertexDataSource<T> m_vertices;
		std::vector<size_t> m_indices;
	public:
		ConvexHull() {}
		
		// Copy constructor
		ConvexHull(const ConvexHull& o) {
			m_indices = o.m_indices;
			if (o.m_optimizedVertexBuffer) {
				m_optimizedVertexBuffer.reset(new std::vector<Vector3<T>>(*o.m_optimizedVertexBuffer));
				m_vertices = VertexDataSource<T>(*m_optimizedVertexBuffer);
			}
			else {
				m_vertices = o.m_vertices;
			}
		}
		
		ConvexHull& operator=(const ConvexHull& o) {
			if (&o == this) {
				return *this;
			}
			m_indices = o.m_indices;
			if (o.m_optimizedVertexBuffer) {
				m_optimizedVertexBuffer.reset(new std::vector<Vector3<T>>(*o.m_optimizedVertexBuffer));
				m_vertices = VertexDataSource<T>(*m_optimizedVertexBuffer);
			}
			else {
				m_vertices = o.m_vertices;
			}
			return *this;
		}
		
		ConvexHull(ConvexHull&& o) {
			m_indices = std::move(o.m_indices);
			if (o.m_optimizedVertexBuffer) {
				m_optimizedVertexBuffer = std::move(o.m_optimizedVertexBuffer);
				o.m_vertices = VertexDataSource<T>();
				m_vertices = VertexDataSource<T>(*m_optimizedVertexBuffer);
			}
			else {
				m_vertices = o.m_vertices;
			}
		}
		
		ConvexHull& operator=(ConvexHull&& o) {
			if (&o == this) {
				return *this;
			}
			m_indices = std::move(o.m_indices);
			if (o.m_optimizedVertexBuffer) {
				m_optimizedVertexBuffer = std::move(o.m_optimizedVertexBuffer);
				o.m_vertices = VertexDataSource<T>();
				m_vertices = VertexDataSource<T>(*m_optimizedVertexBuffer);
			}
			else {
				m_vertices = o.m_vertices;
			}
			return *this;
		}
		
		// Construct vertex and index buffers from half edge mesh and pointcloud
		ConvexHull(const MeshBuilder<T>& mesh, const VertexDataSource<T>& pointCloud, bool CCW, bool useOriginalIndices) {
			if (!useOriginalIndices) {
				m_optimizedVertexBuffer.reset(new std::vector<Vector3<T>>());
			}
			
			std::vector<bool> faceProcessed(mesh.m_faces.size(),false);
			std::vector<size_t> faceStack;
			std::unordered_map<size_t,size_t> vertexIndexMapping; // Map vertex indices from original point cloud to the new mesh vertex indices
			for (size_t i = 0;i<mesh.m_faces.size();i++) {
				if (!mesh.m_faces[i].isDisabled()) {
					faceStack.push_back(i);
					break;
				}
			}
			if (faceStack.size()==0) {
				return;
			}
			
			const size_t finalMeshFaceCount = mesh.m_faces.size() - mesh.m_disabledFaces.size();
			m_indices.reserve(finalMeshFaceCount*3);

			while (faceStack.size()) {
				auto it = faceStack.end()-1;
				size_t top = *it;
				assert(!mesh.m_faces[top].isDisabled());
				faceStack.erase(it);
				if (faceProcessed[top]) {
					continue;
				}
				else {
					faceProcessed[top]=true;
					auto halfEdges = mesh.getHalfEdgeIndicesOfFace(mesh.m_faces[top]);
					size_t adjacent[] = {mesh.m_halfEdges[mesh.m_halfEdges[halfEdges[0]].m_opp].m_face,mesh.m_halfEdges[mesh.m_halfEdges[halfEdges[1]].m_opp].m_face,mesh.m_halfEdges[mesh.m_halfEdges[halfEdges[2]].m_opp].m_face};
					for (auto a : adjacent) {
						if (!faceProcessed[a] && !mesh.m_faces[a].isDisabled()) {
							faceStack.push_back(a);
						}
					}
					auto vertices = mesh.getVertexIndicesOfFace(mesh.m_faces[top]);
					if (!useOriginalIndices) {
						for (auto& v : vertices) {
							auto it = vertexIndexMapping.find(v);
							if (it == vertexIndexMapping.end()) {
								m_optimizedVertexBuffer->push_back(pointCloud[v]);
								vertexIndexMapping[v] = m_optimizedVertexBuffer->size()-1;
								v = m_optimizedVertexBuffer->size()-1;
							}
							else {
								v = it->second;
							}
						}
					}
					m_indices.push_back(vertices[0]);
					if (CCW) {
						m_indices.push_back(vertices[2]);
						m_indices.push_back(vertices[1]);
					}
					else {
						m_indices.push_back(vertices[1]);
						m_indices.push_back(vertices[2]);
					}
				}
			}
			
			if (!useOriginalIndices) {
				m_vertices = VertexDataSource<T>(*m_optimizedVertexBuffer);
			}
			else {
				m_vertices = pointCloud;
			}
		}

		std::vector<size_t>& getIndexBuffer() {
			return m_indices;
		}

		VertexDataSource<T>& getVertexBuffer() {
			return m_vertices;
		}
		
		// Export the mesh to a Waveform OBJ file
		void writeWaveformOBJ(const std::string& filename, const std::string& objectName = "quickhull")
		{
			std::ofstream objFile;
			objFile.open (filename);
			objFile << "o " << objectName << "\n";
			for (const auto& v : getVertexBuffer()) {
				objFile << "v " << v.x << " " << v.y << " " << v.z << "\n";
			}
			const auto& indBuf = getIndexBuffer();
			size_t triangleCount = indBuf.size()/3;
			for (size_t i=0;i<triangleCount;i++) {
				objFile << "f " << indBuf[i*3]+1 << " " << indBuf[i*3+1]+1 << " " << indBuf[i*3+2]+1 << "\n";
			}
			objFile.close();
		}

	};

}

#endif /* CONVEXHULL_HPP_ */