dyna3/engine-proto/gram-test/circles-in-triangle.jl

include("Engine.jl")

using SparseArrays

# initialize the partial gram matrix for a sphere inscribed in a regular
# tetrahedron
J = Int64[]
K = Int64[]
values = BigFloat[]
for j in 1:9
  for k in 1:9
    filled = false
    if j == k
      push!(values, j < 9 ? 1 : 0)
      filled = true
    elseif (j == 9)
      if (k <= 5 && k != 2)
        push!(values, 0)
        filled = true
      end
    elseif (k == 9)
      if (j <= 5 && j != 2)
        push!(values, 0)
        filled = true
      end
    elseif (j == 1 || k == 1)
      push!(values, 0)
      filled = true
    elseif (j == 2 || k == 2)
      push!(values, -1)
      filled = true
    end
    if filled
      push!(J, j)
      push!(K, k)
    end
  end
end
append!(J, [6, 4, 6, 5, 7, 5, 7, 3, 8, 3, 8, 4])
append!(K, [4, 6, 5, 6, 5, 7, 3, 7, 3, 8, 4, 8])
append!(values, fill(-1, 12))
#= make construction rigid
append!(J, [3, 4, 4, 5])
append!(K, [4, 3, 5, 4])
append!(values, fill(-0.5, 4))
=#
gram = sparse(J, K, values)

# set initial guess (random)
## Random.seed!(58271) # stuck; step size collapses on step 48
## Random.seed!(58272) # good convergence
## Random.seed!(58273) # stuck; step size collapses on step 18
## Random.seed!(58274) # stuck
## Random.seed!(58275) #
## guess = Engine.rand_on_shell(fill(BigFloat(-1), 8))

# set initial guess
#=
guess = hcat(
  Engine.plane(BigFloat[0, 0, 1], BigFloat(0)),
  Engine.sphere(BigFloat[0, 0, 0], BigFloat(1//2)),
  Engine.plane(BigFloat[1, 0, 0], BigFloat(1)),
  Engine.plane(BigFloat[cos(2pi/3), sin(2pi/3), 0], BigFloat(1)),
  Engine.plane(BigFloat[cos(-2pi/3), sin(-2pi/3), 0], BigFloat(1)),
  Engine.sphere(BigFloat[-1, 0, 0], BigFloat(1//5)),
  Engine.sphere(BigFloat[cos(-pi/3), sin(-pi/3), 0], BigFloat(1//5)),
  Engine.sphere(BigFloat[cos(pi/3), sin(pi/3), 0], BigFloat(1//5)),
  BigFloat[0, 0, 0, 1, 1]
)
=#
guess = hcat(
  Engine.plane(BigFloat[0, 0, 1], BigFloat(0)),
  Engine.sphere(BigFloat[0, 0, 0], BigFloat(0.9)),
  Engine.plane(BigFloat[1, 0, 0], BigFloat(1)),
  Engine.plane(BigFloat[cos(2pi/3), sin(2pi/3), 0], BigFloat(1)),
  Engine.plane(BigFloat[cos(-2pi/3), sin(-2pi/3), 0], BigFloat(1)),
  Engine.sphere(4//3*BigFloat[-1, 0, 0], BigFloat(1//3)),
  Engine.sphere(4//3*BigFloat[cos(-pi/3), sin(-pi/3), 0], BigFloat(1//3)),
  Engine.sphere(4//3*BigFloat[cos(pi/3), sin(pi/3), 0], BigFloat(1//3)),
  BigFloat[0, 0, 0, 1, 1]
)

# complete the gram matrix using gradient descent
L, history = Engine.realize_gram(gram, guess, max_descent_steps = 200)
completed_gram = L'*Engine.Q*L
println("Completed Gram matrix:\n")
display(completed_gram)
println("\nSteps: ", size(history.stepsize, 1))
println("Loss: ", history.scaled_loss[end], "\n")