v = 0.55
X = vector.new(0,-0.92836897,0.28899258)
Y = vector.new(-0.94538565,0.06753674,0.21695717)
Z = vector.new(0.23369713,0.28899258,0.92836897)
r1 = 40
r2 = 10
a = {1,-2,3,1,0,-1,-1,2,0,0}
b = {-1.2314479651658854,-1.5872747213793104,0.04683103835434217,1.9674748180974897,1.153043896136355,-0.10238369338887907,1.7042206782594087,-1.242120063575402,0.5603127510670854,2.66234724349466}
c = {4.321312860949716,2.116116100402904,2.7194094703705165,3.0821962706516177,5.994638109825947,0.8990716738267982,0.06271719387139103,0.7355961093238955,2.1949825399445198,5.522266625688897}
l = vector.new(0.57735027,0.57735027,0.57735027)
function surface(uv)
    --print("surface")
    total = 0
    for i = 1,#a do
        total = total + math.sin(a[i]*uv.x+math.floor(.5+b[i])*uv.y+c[i])
    end
    return math.pow(math.mod(total,2)-1,2)
end    
function map(xyz)
    --print("map")
    local u = math.atan2(
        xyz:dot(X),xyz:dot(Y)
    )
    local v = math.atan2(
        xyz:dot(Z:normalize()),
        math.sqrt(
            xyz:dot(X)^2+xyz:dot(X)^2
        )
        -r1
    )
    return vector.new(u,v)
end
function lerp(x,y,t)
    --print("lerp")
    return x - (x-y)*t
end
function project(x,y)
    --print("project x:",x," y:",y)
    return x-(
        y*(
            (
                x:dot(
                    y
                )
            )/(
                y:dot(
                    y
                )
            )
        )
    )
end
function setmag(x,y)
    --print("setmag")
    return x:normalize()*y
end
function f(x,y,z)
    --print("f")
    xyz = vector.new(x,y,z)
    dist = (xyz-setmag(project(xyz,Z),r1)):length()-r2
    detail = lerp(5*surface(map(xyz)),r1,v)
    return dist-detail
end
function blockat(x,y,z)
    --print("blockat")
    if f(x,y,z) < 0 then
        flag = false
        for k,v in pairs({
            {1,0,0},
            {0,1,0},
            {0,0,1},
            {-1,0,0},
            {0,-1,0},
            {0,0,-1}
        })do
            flag = f(x+v[1],y+v[2],z+v[3])>0 or flag
        end
        if flag then
            dx = f(x+0.1,y,z)-f(x-0.1,y,z)
            dy = f(x,y+0.1,z)-f(x,y-0.1,z)
            dz = f(x,y,z+0.1)-f(x,y,z-0.1)
            normal = vector.new(dx,dy,dz):normalize()
            if normal:dot(vector.new(0,0,1)) > 0.5 then
                return true, "minecraft:moss_block"
            end
            dot = normal:dot(l)
            lighttable = {
                {-.7,"minecraft:cobbled_deepslate"},
                {-.5,"minecraft:andesite"},
                {-.3,"minecraft:tuff"},
                {0,"minecraft:cobblestone"},
                {.5,"minecraft:diorite"},
                {.7,"create:cut_limestone"},
                {2,"minecraft:calcite"}
            }
            for i,v in ipairs(lighttable) do
                if dot < v[1] then
                    return true, v[2]
                end
            end            
        end
    end
--    print(x,y,z,"is not part of the set")
    return false  
end
return {blockat = blockat}