import igl

V = igl.eigen.MatrixXd()
F = igl.eigen.MatrixXi()
V_uv = igl.eigen.MatrixXd()
initial_guess = igl.eigen.MatrixXd()

show_uv = False

def key_down(viewer, key, modifier):
    global show_uv, V_uv
    if key == ord('1'):
        show_uv = False
    elif key == ord('2'):
        show_uv = True
    elif key == ord('q'):
        V_uv = initial_guess

    if (show_uv):
        viewer.data.set_mesh(V_uv,F)
        viewer.core.align_camera_center(V_uv,F)
    else:
        viewer.data.set_mesh(V,F)
        viewer.core.align_camera_center(V,F)

    viewer.data.compute_normals()
    return False

# Load a mesh in OFF format
igl.readOFF("../tutorial/shared/camelhead.off", V, F)

# Compute the initial solution for ARAP (harmonic parametrization)
bnd = igl.eigen.MatrixXi()
igl.boundary_loop(F,bnd)
bnd_uv = igl.eigen.MatrixXd()
igl.map_vertices_to_circle(V,bnd,bnd_uv)

igl.harmonic(V,F,bnd,bnd_uv,1,initial_guess)

# Add dynamic regularization to avoid to specify boundary conditions
arap_data = igl.ARAPData()
arap_data.with_dynamics = True
b  = igl.eigen.MatrixXi.Zero(0,0);
bc = igl.eigen.MatrixXd.Zero(0,0);

# Initialize ARAP
arap_data.max_iter = 100

# 2 means that we're going to *solve* in 2d
igl.arap_precomputation(V,F,2,b,arap_data)

# Solve arap using the harmonic map as initial guess
V_uv = igl.eigen.MatrixXd(initial_guess) # important, make a copy of it!

igl.arap_solve(bc,arap_data,V_uv)

# Scale UV to make the texture more clear
V_uv *= 20

# Plot the mesh
viewer = igl.viewer.Viewer()
viewer.data.set_mesh(V, F)
viewer.data.set_uv(V_uv)
viewer.callback_key_down = key_down

# Disable wireframe
viewer.core.show_lines = False

# Draw checkerboard texture
viewer.core.show_texture = True

# Launch the viewer
viewer.launch()