Request for automatic handle

[ggaliens]

Micheus ... this is a test REPLY.

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Not working correct yet. Padding at ends logic needs help. And Polykind parameter must get used.

Code:

%% http://stackoverflow.com/questions/7054272/how-to-draw-smooth-curve-through-n-points-using-javascript-html5-canvas
%% TEST : cardinal_spline([0.0,0.0,  1.0,0.0,  1.0,1.0,  0.0,0.0], 12)
cardinal_spline(PTS, PolyKind, NumOfSegments) when is_integer(NumOfSegments)
    when PolyKind == polyline orelse PolyKind == polygon ->
    Tension = 0.7,
    Len = length(PTS),
    _Pts = fun(I0) ->
        I = I0 + Len,
        lists:nth((I rem Len) + 1,PTS)
    end,
    Fun = fun
        (I, Acc) ->
            Fun1 = fun(T, Acc1) ->
                %% calc tension vectors

                T1X = (element(1,_Pts(I+1)) - element(1,_Pts(I-1))) * Tension,
                T2X = (element(1,_Pts(I+2)) - element(1,_Pts(I))) * Tension,

                T1Y = (element(2,_Pts(I+1)) - element(2,_Pts(I-1))) * Tension,
                T2Y = (element(2,_Pts(I+2)) - element(2,_Pts(I))) * Tension,

                T1Z = (element(3,_Pts(I+1)) - element(3,_Pts(I-1))) * Tension,
                T2Z = (element(3,_Pts(I+2)) - element(3,_Pts(I))) * Tension,

                %% calc step
                ST = 1.0 * T / NumOfSegments,
                %% calc cardinals
                C1 =   2.0 * pow(ST,3.0)  - 3.0 * pow(ST,2.0) + 1.0,
                C2 = -(2.0 * pow(ST,3.0)) + 3.0 * pow(ST,2.0),
                C3 =         pow(ST,3.0)  - 2.0 * pow(ST,2.0) + ST,
                C4 =         pow(ST,3.0)  -       pow(ST,2.0),

                %% calc x and y cords with common control vectors
                X = C1 * element(1,_Pts(I))  + C2 * element(1,_Pts(I+1)) + C3 * T1X + C4 * T2X,
                Y = C1 * element(2,_Pts(I))  + C2 * element(2,_Pts(I+1)) + C3 * T1Y + C4 * T2Y,
                Z = C1 * element(3,_Pts(I))  + C2 * element(3,_Pts(I+1)) + C3 * T1Z + C4 * T2Z,

                [{X,Y,Z}|Acc1]

            end,
            lists:foldl(Fun1, Acc, lists:seq(0,NumOfSegments-1))
    end,
    lists:foldl(Fun, [], lists:seq(1,length(PTS)-0)).

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