/** Create a particle model mesh 
*/
void createMesh()
{
	TriangleModel::ParticleMesh::UVs uvs;
	uvs.resize(nRows*nCols);

	const Real dy = width / (Real)(nCols - 1);
	const Real dx = height / (Real)(nRows - 1);

	Vector3r points[nRows*nCols];
	for (int i = 0; i < nRows; i++)
	{
		for (int j = 0; j < nCols; j++)
		{
			const Real y = (Real)dy*j;
			const Real x = (Real)dx*i;
			points[i*nCols + j] = Vector3r(x, 1.0, y);

			uvs[i*nCols + j][0] = x/width;
			uvs[i*nCols + j][1] = y/height;
		}
	}
	const int nIndices = 6 * (nRows - 1)*(nCols - 1);

	TriangleModel::ParticleMesh::UVIndices uvIndices;
	uvIndices.resize(nIndices);

	unsigned int indices[nIndices];
	int index = 0;
	for (int i = 0; i < nRows - 1; i++)
	{
		for (int j = 0; j < nCols - 1; j++)
		{
			int helper = 0;
			if (i % 2 == j % 2)
				helper = 1;

			indices[index] = i*nCols + j;
			indices[index + 1] = i*nCols + j + 1;
			indices[index + 2] = (i + 1)*nCols + j + helper;

			uvIndices[index] = i*nCols + j;
			uvIndices[index + 1] = i*nCols + j + 1;
			uvIndices[index + 2] = (i + 1)*nCols + j + helper;
			index += 3;

			indices[index] = (i + 1)*nCols + j + 1;
			indices[index + 1] = (i + 1)*nCols + j;
			indices[index + 2] = i*nCols + j + 1 - helper;

			uvIndices[index] = (i + 1)*nCols + j + 1;
			uvIndices[index + 1] = (i + 1)*nCols + j;
			uvIndices[index + 2] = i*nCols + j + 1 - helper;
			index += 3;
		}
	}
	model.addTriangleModel(nRows*nCols, nIndices / 3, &points[0], &indices[0], uvIndices, uvs);
	
	ParticleData &pd = model.getParticles();
	for (unsigned int i = 0; i < pd.getNumberOfParticles(); i++)
	{
		pd.setMass(i, 1.0);
	}

	// Set mass of points to zero => make it static
	pd.setMass(0, 0.0);
	pd.setMass((nRows-1)*nCols, 0.0);

	// init constraints
	for (unsigned int cm = 0; cm < model.getTriangleModels().size(); cm++)
	{
		const unsigned int offset = model.getTriangleModels()[cm]->getIndexOffset();
		IndexedFaceMesh &mesh = model.getTriangleModels()[cm]->getParticleMesh();
		const unsigned int nEdges = mesh.numEdges();
		const IndexedFaceMesh::Edge *edges = mesh.getEdges().data();

		// distance constraints
		for (unsigned int i = 0; i < nEdges; i++)
		{
			const unsigned int v1 = edges[i].m_vert[0] + offset;
			const unsigned int v2 = edges[i].m_vert[1] + offset;

			model.addGenericDistanceConstraint(v1, v2);
		}

		// bending constraints
		const unsigned int *tris = mesh.getFaces().data();
		for (unsigned int i = 0; i < nEdges; i++)
		{
			const int tri1 = edges[i].m_face[0];
			const int tri2 = edges[i].m_face[1];
			if ((tri1 != 0xffffffff) && (tri2 != 0xffffffff))
			{
				// Find the triangle points which do not lie on the axis
				const int axisPoint1 = edges[i].m_vert[0];
				const int axisPoint2 = edges[i].m_vert[1];
				int point1 = -1;
				int point2 = -1;
				for (int j = 0; j < 3; j++)
				{
					if ((tris[3 * tri1 + j] != axisPoint1) && (tris[3 * tri1 + j] != axisPoint2))
					{
						point1 = tris[3 * tri1 + j];
						break;
					}
				}
				for (int j = 0; j < 3; j++)
				{
					if ((tris[3 * tri2 + j] != axisPoint1) && (tris[3 * tri2 + j] != axisPoint2))
					{
						point2 = tris[3 * tri2 + j];
						break;
					}
				}
				if ((point1 != -1) && (point2 != -1))
				{
					const unsigned int vertex1 = point1 + offset;
					const unsigned int vertex2 = point2 + offset;
					const unsigned int vertex3 = edges[i].m_vert[0] + offset;
					const unsigned int vertex4 = edges[i].m_vert[1] + offset;
					model.addGenericIsometricBendingConstraint(vertex1, vertex2, vertex3, vertex4);
				}
			}
		}
	}

	std::cout << "Number of triangles: " << nIndices / 3 << "\n";
	std::cout << "Number of vertices: " << nRows*nCols << "\n";

}
/** Create a particle model mesh
*/
void createClothMesh()
{
	TriangleModel::ParticleMesh::UVs uvs;
	uvs.resize(nRows*nCols);

	const float dy = clothWidth / (float)(nCols - 1);
	const float dx = clothHeight / (float)(nRows - 1);

	Eigen::Vector3f points[nRows*nCols];
	for (int i = 0; i < nRows; i++)
	{
		for (int j = 0; j < nCols; j++)
		{
			const float y = (float)dy*j;
			const float x = (float)dx*i;
			points[i*nCols + j] = Eigen::Vector3f(x - 5.0f, 4.0f, y - 5.0f);

			uvs[i*nCols + j][0] = x / clothWidth;
			uvs[i*nCols + j][1] = y / clothHeight;
		}
	}
	const int nIndices = 6 * (nRows - 1)*(nCols - 1);

	TriangleModel::ParticleMesh::UVIndices uvIndices;
	uvIndices.resize(nIndices);

	unsigned int indices[nIndices];
	int index = 0;
	for (int i = 0; i < nRows - 1; i++)
	{
		for (int j = 0; j < nCols - 1; j++)
		{
			int helper = 0;
			if (i % 2 == j % 2)
				helper = 1;

			indices[index] = i*nCols + j;
			indices[index + 1] = i*nCols + j + 1;
			indices[index + 2] = (i + 1)*nCols + j + helper;

			uvIndices[index] = i*nCols + j;
			uvIndices[index + 1] = i*nCols + j + 1;
			uvIndices[index + 2] = (i + 1)*nCols + j + helper;
			index += 3;

			indices[index] = (i + 1)*nCols + j + 1;
			indices[index + 1] = (i + 1)*nCols + j;
			indices[index + 2] = i*nCols + j + 1 - helper;

			uvIndices[index] = (i + 1)*nCols + j + 1;
			uvIndices[index + 1] = (i + 1)*nCols + j;
			uvIndices[index + 2] = i*nCols + j + 1 - helper;
			index += 3;
		}
	}

	model.addTriangleModel(nRows*nCols, nIndices / 3, &points[0], &indices[0], uvIndices, uvs);

	ParticleData &pd = model.getParticles();
	for (unsigned int i = 0; i < pd.getNumberOfParticles(); i++)
	{
		pd.setMass(i, 1.0);
	}

	// init constraints
	for (unsigned int cm = 0; cm < model.getTriangleModels().size(); cm++)
	{
		if (sim.getSimulationMethod() == 1)
		{
			const unsigned int offset = model.getTriangleModels()[cm]->getIndexOffset();
			const unsigned int nEdges = model.getTriangleModels()[cm]->getParticleMesh().numEdges();
			const IndexedFaceMesh::Edge *edges = model.getTriangleModels()[cm]->getParticleMesh().getEdges().data();
			for (unsigned int i = 0; i < nEdges; i++)
			{
				const unsigned int v1 = edges[i].m_vert[0] + offset;
				const unsigned int v2 = edges[i].m_vert[1] + offset;

				model.addDistanceConstraint(v1, v2);
			}
		}
		else if (sim.getSimulationMethod() == 2)
		{
			const unsigned int offset = model.getTriangleModels()[cm]->getIndexOffset();
			TriangleModel::ParticleMesh &mesh = model.getTriangleModels()[cm]->getParticleMesh();
			const unsigned int *tris = mesh.getFaces().data();
			const unsigned int nFaces = mesh.numFaces();
			for (unsigned int i = 0; i < nFaces; i++)
			{
				const unsigned int v1 = tris[3 * i] + offset;
				const unsigned int v2 = tris[3 * i + 1] + offset;
				const unsigned int v3 = tris[3 * i + 2] + offset;
				model.addFEMTriangleConstraint(v1, v2, v3);
			}
		}
		else if (sim.getSimulationMethod() == 3)
		{
			const unsigned int offset = model.getTriangleModels()[cm]->getIndexOffset();
			TriangleModel::ParticleMesh &mesh = model.getTriangleModels()[cm]->getParticleMesh();
			const unsigned int *tris = mesh.getFaces().data();
			const unsigned int nFaces = mesh.numFaces();
			for (unsigned int i = 0; i < nFaces; i++)
			{
				const unsigned int v1 = tris[3 * i] + offset;
				const unsigned int v2 = tris[3 * i + 1] + offset;
				const unsigned int v3 = tris[3 * i + 2] + offset;
				model.addStrainTriangleConstraint(v1, v2, v3);
			}
		}
		if (sim.getBendingMethod() != 0)
		{
			const unsigned int offset = model.getTriangleModels()[cm]->getIndexOffset();
			TriangleModel::ParticleMesh &mesh = model.getTriangleModels()[cm]->getParticleMesh();
			unsigned int nEdges = mesh.numEdges();
			const TriangleModel::ParticleMesh::Edge *edges = mesh.getEdges().data();
			const unsigned int *tris = mesh.getFaces().data();
			for (unsigned int i = 0; i < nEdges; i++)
			{
				const int tri1 = edges[i].m_face[0];
				const int tri2 = edges[i].m_face[1];
				if ((tri1 != 0xffffffff) && (tri2 != 0xffffffff))
				{
					// Find the triangle points which do not lie on the axis
					const int axisPoint1 = edges[i].m_vert[0];
					const int axisPoint2 = edges[i].m_vert[1];
					int point1 = -1;
					int point2 = -1;
					for (int j = 0; j < 3; j++)
					{
						if ((tris[3 * tri1 + j] != axisPoint1) && (tris[3 * tri1 + j] != axisPoint2))
						{
							point1 = tris[3 * tri1 + j];
							break;
						}
					}
					for (int j = 0; j < 3; j++)
					{
						if ((tris[3 * tri2 + j] != axisPoint1) && (tris[3 * tri2 + j] != axisPoint2))
						{
							point2 = tris[3 * tri2 + j];
							break;
						}
					}
					if ((point1 != -1) && (point2 != -1))
					{
						const unsigned int vertex1 = point1 + offset;
						const unsigned int vertex2 = point2 + offset;
						const unsigned int vertex3 = edges[i].m_vert[0] + offset;
						const unsigned int vertex4 = edges[i].m_vert[1] + offset;
						if (sim.getBendingMethod() == 1)
							model.addDihedralConstraint(vertex1, vertex2, vertex3, vertex4);
						else if (sim.getBendingMethod() == 2)
							model.addIsometricBendingConstraint(vertex1, vertex2, vertex3, vertex4);
					}
				}
			}
		}
	}

	std::cout << "Number of triangles: " << nIndices / 3 << "\n";
	std::cout << "Number of vertices: " << nRows*nCols << "\n";

}