def main(): # Get the path for the mesh to load from the program argument if(len(sys.argv) == 3): partString = sys.argv[1] if partString not in ['part1','part2','part3']: print("ERROR part specifier not recognized. Should be one of 'part1', 'part2', or 'part3'") exit() filename = sys.argv[2] else: print("ERROR: Incorrect call syntax. Proper syntax is 'python Assignment3.py partN path/to/your/mesh.obj'.") exit() # Read in the mesh mesh = HalfEdgeMesh(readMesh(filename)) # Create a viewer object winName = 'DDG Assignment3 ' + partString + '-- ' + os.path.basename(filename) meshDisplay = MeshDisplay(windowTitle=winName) meshDisplay.setMesh(mesh) ###################### BEGIN YOUR CODE # implement the body of each of these functions ############################ # Part 0: Helper functions # ############################ # Implement a few useful functions that you will want in the remainder of # the assignment. @property @cacheGeometry def cotanWeight(self): """ Return the cotangent weight for an edge. Since this gets called on an edge, 'self' will be a reference to an edge. This will be useful in the problems below. Don't forget, everything you implemented for the last homework is now available as part of the library (normals, areas, etc). (Moving forward, Vertex.normal will mean area-weighted normals, unless otherwise specified) """ return 0.0 # placeholder value @property @cacheGeometry def dualArea(self): """ Return the dual area associated with a vertex. Since this gets called on a vertex, 'self' will be a reference to a vertex. Recall that the dual area can be defined as 1/3 the area of the surrounding faces. """ return 0.0 # placeholder value def enumerateVertices(mesh): """ Assign a unique index from 0 to (N-1) to each vertex in the mesh. Should return a dictionary containing mappings {vertex ==> index}. You will want to use this function in your solutions below. """ return None # placeholder value ################################# # Part 1: Dense Poisson Problem # ################################# # Solve a Poisson problem on the mesh. The primary function here # is solvePoissonProblem_dense(), it will get called when you run # python Assignment3.py part1 /path/to/your/mesh.obj # and specify density values with the mouse (the press space to solve). # # Note that this code will be VERY slow on large meshes, because it uses # dense matrices. def buildLaplaceMatrix_dense(mesh, index): """ Build a Laplace operator for the mesh, with a dense representation 'index' is a dictionary mapping {vertex ==> index} Returns the resulting matrix. """ return None # placeholder value def buildMassMatrix_dense(mesh, index): """ Build a mass matrix for the mesh. Returns the resulting matrix. """ return None # placeholder value def solvePoissonProblem_dense(mesh, densityValues): """ Solve a Poisson problem on the mesh. The results should be stored on the vertices in a variable named 'solutionVal'. You will want to make use of your buildLaplaceMatrix_dense() function from above. densityValues is a dictionary mapping {vertex ==> value} that specifies densities. The density is implicitly zero at every vertex not in this dictionary. When you run this program with 'python Assignment3.py part1 path/to/your/mesh.obj', you will get to click on vertices to specify density conditions. See the assignment document for more details. """ pass # remove this line once you have implemented the method ################################## # Part 2: Sparse Poisson Problem # ################################## # Solve a Poisson problem on the mesh. The primary function here # is solvePoissonProblem_sparse(), it will get called when you run # python Assignment3.py part2 /path/to/your/mesh.obj # and specify density values with the mouse (the press space to solve). # # This will be very similar to the previous part. Be sure to see the wiki # for notes about the nuances of sparse matrix computation. Now, your code # should scale well to larger meshes! def buildLaplaceMatrix_sparse(mesh, index): """ Build a laplace operator for the mesh, with a sparse representation. This will be nearly identical to the dense method. 'index' is a dictionary mapping {vertex ==> index} Returns the resulting sparse matrix. """ return None # placeholder value def buildMassMatrix_sparse(mesh, index): """ Build a sparse mass matrix for the system. Returns the resulting sparse matrix. """ return None # placeholder value def solvePoissonProblem_sparse(mesh, densityValues): """ Solve a Poisson problem on the mesh, using sparse matrix operations. This will be nearly identical to the dense method. The results should be stored on the vertices in a variable named 'solutionVal'. densityValues is a dictionary mapping {vertex ==> value} that specifies any densities. The density is implicitly zero at every vertex not in this dictionary. Note: Be sure to look at the notes on the github wiki about sparse matrix computation in Python. When you run this program with 'python Assignment3.py part2 path/to/your/mesh.obj', you will get to click on vertices to specify density conditions. See the assignment document for more details. """ pass # remove this line once you have implemented the method ############################### # Part 3: Mean Curvature Flow # ############################### # Perform mean curvature flow on the mesh. The primary function here # is meanCurvatureFlow(), which will get called when you run # python Assignment3.py part3 /path/to/your/mesh.obj # You can adjust the step size with the 'z' and 'x' keys, and press space # to perform one step of flow. # # Of course, you will want to use sparse matrices here, so your code # scales well to larger meshes. def buildMeanCurvatureFlowOperator(mesh, index, h): """ Construct the (sparse) mean curvature operator matrix for the mesh. It might be helpful to use your buildLaplaceMatrix_sparse() and buildMassMatrix_sparse() methods from before. Returns the resulting matrix. """ return None # placeholder value def meanCurvatureFlow(mesh, h): """ Perform mean curvature flow on the mesh. The result of this operation is updated positions for the vertices; you should conclude by modifying the position variables for the mesh vertices. h is the step size for the backwards euler integration. When you run this program with 'python Assignment3.py part3 path/to/your/mesh.obj', you can press the space bar to perform this operation and z/x to change the step size. Recall that before you modify the positions of the mesh, you will need to set mesh.staticGeometry = False, which disables caching optimizations but allows you to modfiy the geometry. After you are done modfiying positions, you should set mesh.staticGeometry = True to re-enable these optimizations. You should probably have mesh.staticGeometry = True while you assemble your operator, or it will be very slow. """ pass # remove this line once you have implemented the method ###################### END YOUR CODE Edge.cotanWeight = cotanWeight Vertex.dualArea = dualArea # A pick function for choosing density conditions densityValues = dict() def pickVertBoundary(vert): value = 1.0 if pickVertBoundary.isHigh else -1.0 print(" Selected vertex at position:" + printVec3(vert.position)) print(" as a density with value = " + str(value)) densityValues[vert] = value pickVertBoundary.isHigh = not pickVertBoundary.isHigh pickVertBoundary.isHigh = True # Run in part1 mode if partString == 'part1': print("\n\n === Executing assignment 2 part 1") print(""" Please click on vertices of the mesh to specify density conditions. Alternating clicks will specify high-value (= 1.0) and low-value (= -1.0) density conditions. You may select as many density vertices as you want, but >= 2 are necessary to yield an interesting solution. When you are done, press the space bar to execute your solver and view the results. """) meshDisplay.pickVertexCallback = pickVertBoundary meshDisplay.drawVertices = True def executePart1Callback(): print("\n=== Solving Poisson problem with your dense solver\n") # Print and check the density values print("Density values:") for key in densityValues: print(" " + str(key) + " = " + str(densityValues[key])) if len(densityValues) < 2: print("Aborting solve, not enough density vertices specified") return # Call the solver print("\nSolving problem...") t0 = time.time() solvePoissonProblem_dense(mesh, densityValues) tSolve = time.time() - t0 print("...solution completed.") print("Solution took {:.5f} seconds.".format(tSolve)) print("Visualizing results...") # Error out intelligently if nothing is stored on vert.solutionVal for vert in mesh.verts: if not hasattr(vert, 'solutionVal'): print("ERROR: At least one vertex does not have the attribute solutionVal defined.") exit() if not isinstance(vert.solutionVal, float): print("ERROR: The data stored at vertex.solutionVal is not of type float.") print(" The data has type=" + str(type(vert.solutionVal))) print(" The data looks like vert.solutionVal="+str(vert.solutionVal)) exit() # Visualize the result # meshDisplay.setShapeColorFromScalar("solutionVal", definedOn='vertex', cmapName="seismic", vMinMax=[-1.0,1.0]) meshDisplay.setShapeColorFromScalar("solutionVal", definedOn='vertex', cmapName="seismic") meshDisplay.generateAllMeshValues() meshDisplay.registerKeyCallback(' ', executePart1Callback, docstring="Solve the Poisson problem and view the results") # Start the GUI meshDisplay.startMainLoop() # Run in part2 mode elif partString == 'part2': print("\n\n === Executing assignment 2 part 2") print(""" Please click on vertices of the mesh to specify density conditions. Alternating clicks will specify high-value (= 1.0) and low-value (= -1.0) density conditions. You may select as many density vertices as you want, but >= 2 are necessary to yield an interesting solution. When you are done, press the space bar to execute your solver and view the results. """) meshDisplay.pickVertexCallback = pickVertBoundary meshDisplay.drawVertices = True def executePart2Callback(): print("\n=== Solving Poisson problem with your sparse solver\n") # Print and check the density values print("Density values:") for key in densityValues: print(" " + str(key) + " = " + str(densityValues[key])) if len(densityValues) < 2: print("Aborting solve, not enough density vertices specified") return # Call the solver print("\nSolving problem...") t0 = time.time() solvePoissonProblem_sparse(mesh, densityValues) tSolve = time.time() - t0 print("...solution completed.") print("Solution took {:.5f} seconds.".format(tSolve)) print("Visualizing results...") # Error out intelligently if nothing is stored on vert.solutionVal for vert in mesh.verts: if not hasattr(vert, 'solutionVal'): print("ERROR: At least one vertex does not have the attribute solutionVal defined.") exit() if not isinstance(vert.solutionVal, float): print("ERROR: The data stored at vertex.solutionVal is not of type float.") print(" The data has type=" + str(type(vert.solutionVal))) print(" The data looks like vert.solutionVal="+str(vert.solutionVal)) exit() # Visualize the result # meshDisplay.setShapeColorFromScalar("solutionVal", definedOn='vertex', cmapName="seismic", vMinMax=[-1.0,1.0]) meshDisplay.setShapeColorFromScalar("solutionVal", definedOn='vertex', cmapName="seismic") meshDisplay.generateAllMeshValues() meshDisplay.registerKeyCallback(' ', executePart2Callback, docstring="Solve the Poisson problem and view the results") # Start the GUI meshDisplay.startMainLoop() # Run in part3 mode elif partString == 'part3': print("\n\n === Executing assignment 2 part 3") print(""" Press the space bar to perform one step of mean curvature flow smoothing, using your solver. Pressing the 'z' and 'x' keys will decrease and increase the step size (h), respectively. """) stepSize = [0.01] def increaseStepsize(): stepSize[0] += 0.001 print("Increasing step size. New size h="+str(stepSize[0])) def decreaseStepsize(): stepSize[0] -= 0.001 print("Decreasing step size. New size h="+str(stepSize[0])) meshDisplay.registerKeyCallback('z', decreaseStepsize, docstring="Increase the value of the step size (h) by 0.1") meshDisplay.registerKeyCallback('x', increaseStepsize, docstring="Decrease the value of the step size (h) by 0.1") def smoothingStep(): print("\n=== Performing mean curvature smoothing step\n") print(" Step size h="+str(stepSize[0])) # Call the solver print(" Solving problem...") t0 = time.time() meanCurvatureFlow(mesh, stepSize[0]) tSolve = time.time() - t0 print(" ...solution completed.") print(" Solution took {:.5f} seconds.".format(tSolve)) print("Updating display...") meshDisplay.generateAllMeshValues() meshDisplay.registerKeyCallback(' ', smoothingStep, docstring="Perform one step of your mean curvature flow on the mesh") # Start the GUI meshDisplay.startMainLoop()
def main(inputfile, show=False, StaticGeometry=False, partString='part1'): # Get the path for the mesh to load from the program argument if (len(sys.argv) == 3): partString = sys.argv[1] if partString not in ['part1', 'part2', 'part3']: print( "ERROR part specifier not recognized. Should be one of 'part1', 'part2', or 'part3'" ) exit() filename = sys.argv[2] elif inputfile is not None: filename = inputfile else: print( "ERROR: Incorrect call syntax. Proper syntax is 'python Assignment3.py partN path/to/your/mesh.obj'." ) exit() # Read in the mesh mesh = HalfEdgeMesh(readMesh(filename), staticGeometry=StaticGeometry) # Create a viewer object winName = 'DDG Assignment3 ' + partString + '-- ' + os.path.basename( filename) meshDisplay = MeshDisplay(windowTitle=winName) meshDisplay.setMesh(mesh) ###################### BEGIN YOUR CODE # implement the body of each of these functions ############################ # assignment 2 code: ############################ @property @cacheGeometry def faceArea(self): """ Compute the area of a face. Though not directly requested, this will be useful when computing face-area weighted normals below. This method gets called on a face, so 'self' is a reference to the face at which we will compute the area. """ v = list(self.adjacentVerts()) a = 0.5 * norm( cross(v[1].position - v[0].position, v[2].position - v[0].position)) return a @property @cacheGeometry def vertexNormal_EquallyWeighted(self): """ Compute a vertex normal using the 'equally weighted' method. This method gets called on a vertex, so 'self' is a reference to the vertex at which we will compute the normal. http://brickisland.net/cs177/?p=217 Perhaps the simplest way to get vertex normals is to just add up the neighboring face normals: """ normalSum = np.array([0.0, 0.0, 0.0]) for face in self.adjacentFaces(): normalSum += face.normal n = normalize(normalSum) #issue: # two different tessellations of the same geometry # can produce very different vertex normals return n @property @cacheGeometry def vertexNormal_AreaWeighted(self): """ Compute a vertex normal using the 'face area weights' method. This method gets called on a vertex, so 'self' is a reference to the vertex at which we will compute the normal. The area-weighted normal vector for this vertex""" normalSum = np.array([0.0, 0.0, 0.0]) for face in self.adjacentFaces(): normalSum += face.normal * face.area n = normalize(normalSum) #print 'computed vertexNormal_AreaWeighted n = ',n return n @property @cacheGeometry def vertexNormal_AngleWeighted(self): """ element type : vertex Compute a vertex normal using the 'Tip-Angle Weights' method. This method gets called on a vertex, so 'self' is a reference to the vertex at which we will compute the normal. A simple way to reduce dependence on the tessellation is to weigh face normals by their corresponding tip angles theta, i.e., the interior angles incident on the vertex of interest: """ normalSum = np.array([0.0, 0.0, 0.0]) for face in self.adjacentFaces(): vl = list(face.adjacentVerts()) vl.remove(self) v1 = vl[0].position - self.position v2 = vl[1].position - self.position # norm ->no need for check: # it doesn not matter what the sign is? #area = norm(cross(v1, v2)) ##if area < 0.0000000001*max((norm(v1),norm(v2))): #if area < 0.: # area *= -1. alpha = np.arctan2(norm(cross(v1, v2)), dot(v1, v2)) #print v1 #print v2 #print alpha #print '' normalSum += face.normal * alpha n = normalize(normalSum) return n @property @cacheGeometry def faceNormal(self): """ Compute normal at a face of the mesh. Unlike at vertices, there is one very obvious way to do this, since a face uniquely defines a plane. This method gets called on a face, so 'self' is a reference to the face at which we will compute the normal. """ v = list(self.adjacentVerts()) n = normalize( cross(v[1].position - v[0].position, v[2].position - v[0].position)) return n @property @cacheGeometry def cotan(self): """ element type : halfedge Compute the cotangent of the angle OPPOSITE this halfedge. This is not directly required, but will be useful when computing the mean curvature normals below. This method gets called on a halfedge, so 'self' is a reference to the halfedge at which we will compute the cotangent. https://math.stackexchange.com/questions/2041099/ angle-between-vectors-given-cross-and-dot-product see half edge here: Users/lukemcculloch/Documents/Coding/Python/ DifferentialGeometry/course-master/libddg_userguide.pdf """ # Validate that this is on a triangle if self.next.next.next is not self: raise ValueError( "ERROR: halfedge.cotan() is only well-defined on a triangle") if self.isReal: # Relevant vectors A = -self.next.vector B = self.next.next.vector # Nifty vector equivalent of cot(theta) val = np.dot(A, B) / norm(cross(A, B)) return val else: return 0.0 @property @cacheGeometry def angleDefect(self): """ angleDefect <=> local Gaussian Curvature element type : vertex Compute the angle defect of a vertex, d(v) (see Assignment 1 Exercise 8). This method gets called on a vertex, so 'self' is a reference to the vertex at which we will compute the angle defect. """ """ el = list(self.adjacentEdges()) evpl = list(self.adjacentEdgeVertexPairs()) fl = list(self.adjacentFaces()) vl = list(self.adjacentVerts()) https://scicomp.stackexchange.com/questions/27689/ numerically-stable-way-of-computing-angles-between-vectors #""" hl = list(self.adjacentHalfEdges()) lenhl = len(hl) hl.append(hl[0]) alpha = 0. for i in range(lenhl): v1 = hl[i].vector v2 = hl[i + 1].vector alpha += np.arctan2(norm(cross(v1, v2)), dot(v1, v2)) #dv = 2.*np.pi - alpha return 2. * np.pi - alpha def totalGaussianCurvature(): """ Compute the total Gaussian curvature in the mesh, meaning the sum of Gaussian curvature at each vertex. Note that you can access the mesh with the 'mesh' variable. """ tot = 0. for vel in mesh.verts: tot += vel.angleDefect return tot def gaussianCurvatureFromGaussBonnet(): """ Compute the total Gaussian curvature that the mesh should have, given that the Gauss-Bonnet theorem holds (see Assignment 1 Exercise 9). Note that you can access the mesh with the 'mesh' variable. The mesh includes members like 'mesh.verts' and 'mesh.faces', which are sets of the vertices (resp. faces) in the mesh. """ V = len(mesh.verts) E = len(mesh.edges) F = len(mesh.faces) EulerChar = V - E + F return 2. * np.pi * EulerChar ############################ # Part 0: Helper functions # ############################ # Implement a few useful functions that you will want in the remainder of # the assignment. @property @cacheGeometry def cotanWeight(self): """ Return the cotangent weight for an edge. Since this gets called on an edge, 'self' will be a reference to an edge. This will be useful in the problems below. Don't forget, everything you implemented for the last homework is now available as part of the library (normals, areas, etc). (Moving forward, Vertex.normal will mean area-weighted normals, unless otherwise specified) """ val = 0.0 if self.anyHalfEdge.isReal: val += self.anyHalfEdge.cotan if self.anyHalfEdge.twin.isReal: val += self.anyHalfEdge.twin.cotan val *= 0.5 return val @property @cacheGeometry def vertex_Laplace(self): """ element type : vertex Compute a vertex normal using the 'mean curvature' method. del del phi = 2NH -picked up negative sign due to cross products pointing into the page? -no they are normalized. -picked up a negative sign due to the cotan(s) being defined for pj, instead of pi. But how did it change anything? """ hl = list(self.adjacentHalfEdges()) pi = self.position sumj = 0. ot = 1. / 3. for hlfedge in hl: pj = hlfedge.vertex.position ct1 = hlfedge.cotan ct2 = hlfedge.twin.cotan sumj += (ct1 + ct2) * (pj - pi) #laplace = .5*sumj return normalize(-.5 * sumj) ## ##******************************************************* ## @property @cacheGeometry def dualArea(self): """ Return the dual area associated with a vertex. Since this gets called on a vertex, 'self' will be a reference to a vertex. Recall that the dual area can be defined as 1/3 the area of the surrounding faces. http://brickisland.net/DDGFall2017/ 'the barycentric dual area associated with a vertex i is equal to one-third the area of all triangles ijk touching i.' """ fl = list(self.adjacentFaces()) area_star = 0. for ff in fl: area_star += ff.area / 3. return area_star def enumerateVertices(mesh): """ Assign a unique index from 0 to (N-1) to each vertex in the mesh. Should return a dictionary containing mappings {vertex ==> index}. You will want to use this function in your solutions below. """ # index_map = {} # index = 0 # for vv in mesh.verts: # index_map[vv] = index # index += 1 return mesh.enumerateVertices @property @cacheGeometry def adjacency(self): index_map = enumerateVertices(self) nrows = ncols = len(mesh.verts) adjacency = np.zeros((nrows, ncols), int) for vv in mesh.verts: ith = index_map[vv] avlist = list(vv.adjacentVerts()) for av in avlist: jth = index_map[av] adjacency[ith, jth] = 1 return adjacency ################################# # Part 1: Dense Poisson Problem # ################################# # Solve a Poisson problem on the mesh. The primary function here # is solvePoissonProblem_dense(), it will get called when you run # python Assignment3.py part1 /path/to/your/mesh.obj # and specify density values with the mouse (the press space to solve). # # Note that this code will be VERY slow on large meshes, because it uses # dense matrices. def buildLaplaceMatrix_dense(mesh, index_map=None): """ Build a Laplace operator for the mesh, with a dense representation 'index' is a dictionary mapping {vertex ==> index} TLM renamed to index_map Returns the resulting matrix. """ if index_map is None: # index_map = mesh.enumerateVertices() index_map = enumerateVertices(mesh) nrows = ncols = len(mesh.verts) adjacency = np.zeros((nrows, ncols), int) for vv in mesh.verts: ith = index_map[vv] avlist = list(vv.adjacentVerts()) for av in avlist: jth = index_map[av] adjacency[ith, jth] = 1 Laplacian = np.zeros((nrows, ncols), float) for vi in mesh.verts: ith = index_map[vi] ll = list(vi.adjacentEdgeVertexPairs()) for edge, vj in ll: jth = index_map[vj] # Laplacian[ith,jth] = np.dot(vj.normal, # edge.cotanWeight*(vj.position - # vi.position) # ) if ith == jth: pass #Laplacian[ith,jth] = edge.cotanWeight else: Laplacian[ith, jth] = edge.cotanWeight Laplacian[ith, ith] = -sum(Laplacian[ith]) return Laplacian def buildMassMatrix_dense(mesh, index): """ Build a mass matrix for the mesh. Returns the resulting matrix. """ nrows = ncols = len(mesh.verts) #MassMatrix = np.zeros((nrows),float) MassMatrix = np.zeros((nrows, ncols), float) for i, vert in enumerate(mesh.verts): #MassMatrix[i,i] = 1./vert.dualArea MassMatrix[i, i] = vert.dualArea return MassMatrix def solvePoissonProblem_dense(mesh, densityValues): """ Solve a Poisson problem on the mesh. The results should be stored on the vertices in a variable named 'solutionVal'. You will want to make use of your buildLaplaceMatrix_dense() function from above. densityValues is a dictionary mapping {vertex ==> value} that specifies densities. The density is implicitly zero at every vertex not in this dictionary. When you run this program with 'python Assignment3.py part1 path/to/your/mesh.obj', you will get to click on vertices to specify density conditions. See the assignment document for more details. """ index_map = enumerateVertices(mesh) L = buildLaplaceMatrix_dense(mesh, index_map) M = buildMassMatrix_dense(mesh, index_map) #M <= 2D rho = np.zeros((len(mesh.verts)), float) for key in densityValues: #index_val = index_map[key] print 'key dual area = ', key.dualArea rho[index_map[key]] = densityValues[key] #*key.dualArea # # SwissArmyLaplacian, # page 179 Cu = Mf is better conditioned sol_vec = np.linalg.solve(L, np.dot(M, rho)) #sparse attempts: #sol_vec = linsolve.spsolve(L, rho) #sol_vec = dsolve.spsolve(L, rho, use_umfpack=False) #sol_vec = dsolve.spsolve(L, rho, use_umfpack=True) for vert in mesh.verts: key = index_map[vert] #print 'TLM sol_vec = ',sol_vec[key] vert.solutionVal = sol_vec[key] if rho[key]: vert.densityVal = rho[key] else: vert.densityVal = 0. return ################################## # Part 2: Sparse Poisson Problem # ################################## # Solve a Poisson problem on the mesh. The primary function here # is solvePoissonProblem_sparse(), it will get called when you run # python Assignment3.py part2 /path/to/your/mesh.obj # and specify density values with the mouse (the press space to solve). # # This will be very similar to the previous part. Be sure to see the wiki # for notes about the nuances of sparse matrix computation. Now, your code # should scale well to larger meshes! def buildLaplaceMatrix_sparse(mesh, index_map=None): """ Build a laplace operator for the mesh, with a sparse representation. This will be nearly identical to the dense method. 'index' is a dictionary mapping {vertex ==> index} Returns the resulting sparse matrix. """ if index_map is None: # index_map = mesh.enumerateVertices() index_map = enumerateVertices(mesh) nrows = ncols = len(mesh.verts) adjacency = np.zeros((nrows, ncols), int) for vv in mesh.verts: ith = index_map[vv] avlist = list(vv.adjacentVerts()) for av in avlist: jth = index_map[av] adjacency[ith, jth] = 1 Laplacian = np.zeros((nrows, ncols), float) for vi in mesh.verts: ith = index_map[vi] ll = list(vi.adjacentEdgeVertexPairs()) for edge, vj in ll: jth = index_map[vj] # Laplacian[ith,jth] = np.dot(vj.normal, # edge.cotanWeight*(vj.position - # vi.position) # ) if ith == jth: pass #Laplacian[ith,jth] = edge.cotanWeight else: Laplacian[ith, jth] = edge.cotanWeight Laplacian[ith, ith] = -sum(Laplacian[ith]) return csr_matrix(Laplacian) def buildMassMatrix_sparse(mesh, index): """ Build a sparse mass matrix for the system. Returns the resulting sparse matrix. """ nrows = ncols = len(mesh.verts) MassMatrix = np.zeros((nrows), float) #for i,vert in enumerate(mesh.verts): # MassMatrix[i] = vert.dualArea return MassMatrix def solvePoissonProblem_sparse(mesh, densityValues): """ Solve a Poisson problem on the mesh, using sparse matrix operations. This will be nearly identical to the dense method. The results should be stored on the vertices in a variable named 'solutionVal'. densityValues is a dictionary mapping {vertex ==> value} that specifies any densities. The density is implicitly zero at every vertex not in this dictionary. Note: Be sure to look at the notes on the github wiki about sparse matrix computation in Python. When you run this program with 'python Assignment3.py part2 path/to/your/mesh.obj', you will get to click on vertices to specify density conditions. See the assignment document for more details. """ index_map = enumerateVertices(mesh) L = buildLaplaceMatrix_sparse(mesh, index_map) M = buildMassMatrix_dense(mesh, index_map) #M <= 2D rho = np.zeros((len(mesh.verts)), float) for key in densityValues: #index_val = index_map[key] print 'key dual area = ', key.dualArea rho[index_map[key]] = densityValues[key] #*key.dualArea # convert to sparse matrix (CSR method) #Lsparse = csr_matrix(L) #iL = np.linalg.inv(L) #sol_vec = np.dot(iL,rho) #sol_vec = np.linalg.solve(L, rho) #sol_vec = linsolve.spsolve(L, rho) #sol_vec = linsolve.spsolve(L, np.dot(M,rho) ) #sol_vec = dsolve.spsolve(L, rho, use_umfpack=False) sol_vec = dsolve.spsolve(L, np.dot(M, rho), use_umfpack=True) for vert in mesh.verts: key = index_map[vert] #print 'TLM sol_vec = ',sol_vec[key] vert.solutionVal = sol_vec[key] if rho[key]: vert.densityVal = rho[key] else: vert.densityVal = 0. return ############################### # Part 3: Mean Curvature Flow # ############################### # Perform mean curvature flow on the mesh. The primary function here # is meanCurvatureFlow(), which will get called when you run # python Assignment3.py part3 /path/to/your/mesh.obj # You can adjust the step size with the 'z' and 'x' keys, and press space # to perform one step of flow. # # Of course, you will want to use sparse matrices here, so your code # scales well to larger meshes. def buildMeanCurvatureFlowOperator(mesh, index=None, h=None): """ Construct the (sparse) mean curvature operator matrix for the mesh. It might be helpful to use your buildLaplaceMatrix_sparse() and buildMassMatrix_sparse() methods from before. Returns the resulting matrix. """ nrows = ncols = len(mesh.verts) ##MassMatrix = np.zeros((nrows),float) #MassMatrix = np.zeros((nrows,ncols),float) #for i,vert in enumerate(mesh.verts): # MassMatrix[i] = 1./vert.dualArea # #MassMatrix[i,i] = 1./vert.dualArea Laplacian = np.zeros((nrows, ncols), float) for vi in mesh.verts: ith = index[vi] ll = list(vi.adjacentEdgeVertexPairs()) for edge, vj in ll: jth = index[vj] # Laplacian[ith,jth] = np.dot(vj.normal, # edge.cotanWeight*(vj.position - # vi.position) # ) if ith == jth: pass #Laplacian[ith,jth] = edge.cotanWeight else: Laplacian[ith, jth] = edge.cotanWeight Laplacian[ith, ith] = -sum(Laplacian[ith]) return csr_matrix(Laplacian) def meanCurvatureFlow_use_numpy_solve(mesh, h): """ Perform mean curvature flow on the mesh. The result of this operation is updated positions for the vertices; you should conclude by modifying the position variables for the mesh vertices. h is the step size for the backwards euler integration. When you run this program with 'python Assignment3.py part3 path/to/your/mesh.obj', you can press the space bar to perform this operation and z/x to change the step size. Recall that before you modify the positions of the mesh, you will need to set mesh.staticGeometry = False, which disables caching optimizations but allows you to modfiy the geometry. After you are done modfiying positions, you should set mesh.staticGeometry = True to re-enable these optimizations. You should probably have mesh.staticGeometry = True while you assemble your operator, or it will be very slow. """ # index_map = mesh.enumerateVertices() index_map = enumerateVertices(mesh) nrows = ncols = len(mesh.verts) Id = np.identity(nrows, float) M = buildMassMatrix_dense(mesh, index_map) #M <= 2D MCF = buildMeanCurvatureFlowOperator(mesh, index=index_map, h=h) # # SwissArmyLaplacian, # page 181 (I-hC)u = u is not symmetric # (M-hC)u = Mu is better conditioned #---------------------------------------------- Mi = np.linalg.inv(M) L = np.matmul(Mi, MCF) #UpdateOperator = np.linalg.inv(Id-h*L) #---------------------------------------------- #UpdateOperator = np.linalg.inv(M-h*MCF) LHS = M - h * MCF UpdateOperator = np.linalg.inv(LHS) #UpdateOperator = np.matmul(UpdateOperator,M) vertices = np.zeros((nrows, 3), float) for i, vert in enumerate(mesh.verts): vertices[i] = vert.position LHS = Id - h * L UpdateOperator = np.linalg.solve(LHS, vertices) vertices = UpdateOperator for i, vert in enumerate(mesh.verts): #key = index_map[vert] vert.position = vertices[i] # # vertices = np.dot(UpdateOperator,vertices) # for i,vert in enumerate(mesh.verts): # key = index_map[vert] # vert.position = vertices[i] return def meanCurvatureFlow(mesh, h): """ Perform mean curvature flow on the mesh. The result of this operation is updated positions for the vertices; you should conclude by modifying the position variables for the mesh vertices. h is the step size for the backwards euler integration. When you run this program with 'python Assignment3.py part3 path/to/your/mesh.obj', you can press the space bar to perform this operation and z/x to change the step size. Recall that before you modify the positions of the mesh, you will need to set mesh.staticGeometry = False, which disables caching optimizations but allows you to modfiy the geometry. After you are done modfiying positions, you should set mesh.staticGeometry = True to re-enable these optimizations. You should probably have mesh.staticGeometry = True while you assemble your operator, or it will be very slow. """ # index_map = mesh.enumerateVertices() index_map = enumerateVertices(mesh) nrows = ncols = len(mesh.verts) #Id = np.identity(nrows,float) M = buildMassMatrix_dense(mesh, index_map) #M <= 2D Msp = csr_matrix(M) #pure cotan operator: MCF = buildMeanCurvatureFlowOperator(mesh, index=index_map, h=h) # # SwissArmyLaplacian, # page 181 (I-hC)u = u is not symmetric # (M-hC)u = Mu is better conditioned #---------------------------------------------- #Mi = np.linalg.inv(M) #L = np.matmul(Mi,MCF) #UpdateOperator = np.linalg.inv(Id-h*L) #---------------------------------------------- #LHS = M-h*MCF LHS = Msp - MCF.multiply(h) #UpdateOperator = np.linalg.inv(LHS) #UpdateOperator = np.matmul(UpdateOperator,M) UpdateOperator = dsolve.spsolve(LHS, M, use_umfpack=True) vertices = np.zeros((nrows, 3), float) for i, vert in enumerate(mesh.verts): vertices[i] = vert.position #https://docs.scipy.org/doc/scipy-0.14.0/reference/generated/scipy.linalg.cho_solve.html #UpdateOperator = scipy.linalg.cho_solve( # scipy.linalg.cho_factor(LHS), # np.dot(M,vertices)) #P, L, U = scipy.linalg.lu(LHS) # for non symmetric, numpy solve, style: # LHS = Id-h*L # UpdateOperator = np.linalg.solve(LHS, vertices) # vertices = UpdateOperator # for i,vert in enumerate(mesh.verts): # #key = index_map[vert] # vert.position = vertices[i] # vertices = np.dot(UpdateOperator, vertices) for i, vert in enumerate(mesh.verts): #key = index_map[vert] vert.position = vertices[i] return ###################### END YOUR CODE # from assignment 2: Face.normal = faceNormal Face.area = faceArea Vertex.normal = vertexNormal_AreaWeighted Vertex.vertexNormal_EquallyWeighted = vertexNormal_EquallyWeighted Vertex.vertexNormal_AreaWeighted = vertexNormal_AreaWeighted Vertex.vertexNormal_AngleWeighted = vertexNormal_AngleWeighted ## Vertex.vertex_Laplace = vertex_Laplace # #Vertex.vertexNormal_SphereInscribed = vertexNormal_SphereInscribed Vertex.angleDefect = angleDefect HalfEdge.cotan = cotan def toggleDefect(): print("\nToggling angle defect display") if toggleDefect.val: toggleDefect.val = False meshDisplay.setShapeColorToDefault() else: toggleDefect.val = True meshDisplay.setShapeColorFromScalar("angleDefect", cmapName="seismic") #,vMinMax=[-pi/8,pi/8]) meshDisplay.generateFaceData() toggleDefect.val = False meshDisplay.registerKeyCallback( '3', toggleDefect, docstring="Toggle drawing angle defect coloring") def computeDiscreteGaussBonnet(): print("\nComputing total curvature:") computed = totalGaussianCurvature() predicted = gaussianCurvatureFromGaussBonnet() print(" Total computed curvature: " + str(computed)) print(" Predicted value from Gauss-Bonnet is: " + str(predicted)) print(" Error is: " + str(abs(computed - predicted))) meshDisplay.registerKeyCallback('z', computeDiscreteGaussBonnet, docstring="Compute total curvature") ###################### Assignment 3 stuff Edge.cotanWeight = cotanWeight Vertex.dualArea = dualArea # A pick function for choosing density conditions densityValues = dict() def pickVertBoundary(vert): """ See MeshDisplay callbacks, pickVertexCallback for how this works! self.pickVertexCallback <== pickVertBoundary(vert) self.pickVertexCallback(pickObject = your_vertex) """ value = 1.0 if pickVertBoundary.isHigh else -1.0 print(" Selected vertex at position:" + printVec3(vert.position)) print(" as a density with value = " + str(value)) densityValues[vert] = value print 'densityValues = ', densityValues pickVertBoundary.isHigh = not pickVertBoundary.isHigh pickVertBoundary.isHigh = True # Run in part1 mode if partString == 'part1': print("\n\n === Executing assignment 2 part 1") print(""" Please click on vertices of the mesh to specify density conditions. Alternating clicks will specify high-value (= 1.0) and low-value (= -1.0) density conditions. You may select as many density vertices as you want, but >= 2 are necessary to yield an interesting solution. When you are done, press the space bar to execute your solver and view the results. """) meshDisplay.pickVertexCallback = pickVertBoundary meshDisplay.drawVertices = True def executePart1Callback(): print("\n=== Solving Poisson problem with your dense solver\n") # Print and check the density values print("Density values:") for key in densityValues: print(" " + str(key) + " = " + str(densityValues[key])) #if len(densityValues) < 2: # print("Aborting solve, not enough density vertices specified") # return # Call the solver print("\nSolving problem...") t0 = time.time() solvePoissonProblem_dense(mesh, densityValues) tSolve = time.time() - t0 print("...solution completed.") print("Solution took {:.5f} seconds.".format(tSolve)) print("Visualizing results...") # Error out intelligently if nothing is stored on vert.solutionVal for vert in mesh.verts: if not hasattr(vert, 'solutionVal'): print( "ERROR: At least one vertex does not have the attribute solutionVal defined." ) exit() if not isinstance(vert.solutionVal, float): print( "ERROR: The data stored at vertex.solutionVal is not of type float." ) print(" The data has type=" + str(type(vert.solutionVal))) print(" The data looks like vert.solutionVal=" + str(vert.solutionVal)) exit() # Visualize the result # meshDisplay.setShapeColorFromScalar("solutionVal", # definedOn='vertex', # cmapName="seismic", # vMinMax=[-10.0,10.0]) meshDisplay.setShapeColorFromScalar("solutionVal", definedOn='vertex', cmapName="seismic") meshDisplay.generateAllMeshValues() meshDisplay.registerKeyCallback( ' ', executePart1Callback, docstring="Solve the Poisson problem and view the results") def showdensity(): # Visualize the result # meshDisplay.setShapeColorFromScalar("densityVal", # definedOn='vertex', # cmapName="seismic", # vMinMax=[-1.0,1.0]) meshDisplay.setShapeColorFromScalar("densityVal", definedOn='vertex', cmapName="seismic") meshDisplay.generateAllMeshValues() meshDisplay.registerKeyCallback( 'b', showdensity, docstring="Show the density map for the Poisson Problem") # Start the GUI if show: meshDisplay.startMainLoop() # Run in part2 mode elif partString == 'part2': print("\n\n === Executing assignment 2 part 2") print(""" Please click on vertices of the mesh to specify density conditions. Alternating clicks will specify high-value (= 1.0) and low-value (= -1.0) density conditions. You may select as many density vertices as you want, but >= 2 are necessary to yield an interesting solution. When you are done, press the space bar to execute your solver and view the results. """) meshDisplay.pickVertexCallback = pickVertBoundary meshDisplay.drawVertices = True def executePart2Callback(): print("\n=== Solving Poisson problem with your sparse solver\n") # Print and check the density values print("Density values:") for key in densityValues: print(" " + str(key) + " = " + str(densityValues[key])) #if len(densityValues) < 2: # print("Aborting solve, not enough density vertices specified") # return # Call the solver print("\nSolving problem...") t0 = time.time() solvePoissonProblem_sparse(mesh, densityValues) tSolve = time.time() - t0 print("...solution completed.") print("Solution took {:.5f} seconds.".format(tSolve)) print("Visualizing results...") # Error out intelligently if nothing is stored on vert.solutionVal for vert in mesh.verts: if not hasattr(vert, 'solutionVal'): print( "ERROR: At least one vertex does not have the attribute solutionVal defined." ) exit() if not isinstance(vert.solutionVal, float): print( "ERROR: The data stored at vertex.solutionVal is not of type float." ) print(" The data has type=" + str(type(vert.solutionVal))) print(" The data looks like vert.solutionVal=" + str(vert.solutionVal)) exit() # Visualize the result # meshDisplay.setShapeColorFromScalar("solutionVal", definedOn='vertex', cmapName="seismic", vMinMax=[-1.0,1.0]) meshDisplay.setShapeColorFromScalar("solutionVal", definedOn='vertex', cmapName="seismic") meshDisplay.generateAllMeshValues() meshDisplay.registerKeyCallback( ' ', executePart2Callback, docstring="Solve the Poisson problem and view the results") # Start the GUI if show: meshDisplay.startMainLoop() # Run in part3 mode elif partString == 'part3': print("\n\n === Executing assignment 2 part 3") print(""" Press the space bar to perform one step of mean curvature flow smoothing, using your solver. Pressing the 'z' and 'x' keys will decrease and increase the step size (h), respectively. """) stepSize = [0.01] def increaseStepsize(): stepSize[0] += 0.001 print("Increasing step size. New size h=" + str(stepSize[0])) def decreaseStepsize(): stepSize[0] -= 0.001 print("Decreasing step size. New size h=" + str(stepSize[0])) meshDisplay.registerKeyCallback( 'z', decreaseStepsize, docstring="Increase the value of the step size (h) by 0.1") meshDisplay.registerKeyCallback( 'x', increaseStepsize, docstring="Decrease the value of the step size (h) by 0.1") def smoothingStep(): print("\n=== Performing mean curvature smoothing step\n") print(" Step size h=" + str(stepSize[0])) # Call the solver print(" Solving problem...") t0 = time.time() meanCurvatureFlow(mesh, stepSize[0]) tSolve = time.time() - t0 print(" ...solution completed.") print(" Solution took {:.5f} seconds.".format(tSolve)) print("Updating display...") meshDisplay.generateAllMeshValues() meshDisplay.registerKeyCallback( ' ', smoothingStep, docstring="Perform one step of your mean curvature flow on the mesh" ) # Start the GUI if show: meshDisplay.startMainLoop() return mesh, meshDisplay