using StaticArrays
using Delaunay
using  PlotlyJS
include("src/plotlyju.jl");

function gen_trimesh_points(T₁, T₂, T₃, n=21)
    # T_1, T_2, T_3 are  the vertices of a  triangle 
    # it generates (n+1)(n+2)/2 points as a triangular grid  over  the triangle T_1T_2T_3
    
    ## vector of  barycentric coordinates 
    B = [[i/n, j/n, (n-(i+j))/n] for i in n:-1:0 for j in n-i:-1:0]
    #conversion to cartesian coordinates
    pts_vect = [SVector{2, Float64}(b[1]*T₁+b[2]*T₂ +b[3]*T₃) for b in B] 
    pts_matr = reshape(reinterpret(Float64, pts_vect), (2, length(pts_vect)))'
    return pts_matr
end  

f(x,y) = -cos(x)*sin(x*y);

T₁, T₂, T₃ = [-2.0, -2*sqrt(3)/3],  [2.0, -2*sqrt(3)/3], [0.0, 4*sqrt(3)/3] 
points = gen_trimesh_points(T₁, T₂, T₃) #N=22*23/2=253 points
mesh = delaunay(Matrix(points))
triangles = mesh.simplices .- 1; 
x, y = points[:, 1], points[:, 2]
z = f.(x,y);

triangular_surf = mesh3d(x=x, y=y, 
                         z=z, 
                         i=triangles[:, 1], 
                         j=triangles[:, 2], 
                         k=triangles[:, 3],
                         intensity=z,
                         colorbar_len=0.7
            )
data = AbstractTrace[]
push!(data, triangular_surf)

#project surf onto the plane z=h:
h = -2
z_proj = h * ones(size(z)) 

proj_surf = mesh3d(x=x, y=y, z=z_proj,
                   i=triangles[:, 1], 
                   j=triangles[:, 2], 
                   k=triangles[:, 3],
                   intensity=z,
                   showscale=false)
push!(data, proj_surf)
layout = Layout(width=600, height=600, 
               #margin=attr(l=50, t=10, r=50, b=10),
               scene_camera_eye=attr(x=1.75, y=1.75, z=0.9))
pl = Plot(data, layout, style=plotlyju)