ReCo.jl/graphics/verlet_and_cell_lists.jl

using Luxor
using Random: Random
using StaticArrays: SVector

using ReCo: ReCo

function gen_verlet_and_cell_lists_graphics()
    Random.seed!(3)

    box_length = 100

    graphics_export_dir = "exports/graphics"
    mkpath(graphics_export_dir)

    Drawing(box_length, box_length, "$graphics_export_dir/verlet_and_cell_lists.pdf")
    origin()

    R_particle = 4.2
    σ = 2 * R_particle * 2^(-1 / 6)
    R_interaction = 2^(1 / 6) * σ
    R_skin = ReCo.DEFAULT_SKIN_TO_INTERACTION_RADIUS_RATIO * R_interaction

    setcolor("blue")
    reference_particle_x = 0.25 * R_skin
    reference_particle_y = -0.1 * R_skin
    circle(Point(reference_particle_x, reference_particle_y), R_particle, :fill)
    reference_particle_c = SVector(reference_particle_x, reference_particle_y)

    N = 107

    particle_cs = Vector{SVector{2,Float64}}(undef, N)

    distance_limit = 0.98 * 2 * R_particle

    x = y = distance = 0.0

    for p1_ind in 1:N
        while true
            x = (rand() - 0.5) * box_length
            y = (rand() - 0.5) * box_length

            p1_c = SVector(x, y)

            distance = ReCo.norm2d(p1_c - reference_particle_c)

            no_collision = true

            if distance >= distance_limit
                for p2_ind in 1:(p1_ind - 1)
                    if ReCo.norm2d(p1_c - particle_cs[p2_ind]) < distance_limit
                        no_collision = false

                        break
                    end
                end

                if no_collision
                    particle_cs[p1_ind] = p1_c
                    break
                end
            end
        end

        if distance < R_interaction
            setcolor("red")
        elseif R_interaction <= distance < R_skin
            setcolor("green")
        else
            setcolor("orange")
        end

        circle(x, y, R_particle, :fill)
    end

    setcolor("black")
    setline(0.28)
    for R in (R_interaction, R_skin)
        circle(Point(reference_particle_x, reference_particle_y), R, :stroke)
    end

    half_n_lines = floor(Int64, box_length / (2 * R_skin) + 0.5)
    for i in 1:half_n_lines
        coordinate = (i - 0.5) * R_skin
        line(Point(coordinate, -box_length), Point(coordinate, box_length), :stroke)
        line(Point(-coordinate, -box_length), Point(-coordinate, box_length), :stroke)
        line(Point(-box_length, coordinate), Point(box_length, coordinate), :stroke)
        line(Point(-box_length, -coordinate), Point(box_length, -coordinate), :stroke)
    end

    setcolor((0.2, 0.0, 1.0, 0.3))
    rect(-1.5 * R_skin, -1.5 * R_skin, 3 * R_skin, 3 * R_skin, :fill)

    finish()

    return nothing
end