unit uLandOutline;

interface

uses uConsts, SDLh, uFloat;

type TPixAr = record

              Count: Longword;

              ar: array[0..Pred(cMaxEdgePoints)] of TPoint;

              end;

procedure DrawEdge(var pa: TPixAr; value: Word);

procedure BezierizeEdge(var pa: TPixAr; Delta: hwFloat);

implementation

var Stack: record

           Count: Longword;

           points: array[0..8192] of record

                                     xl, xr, y, dir: LongInt;

                                     end

           end;

procedure Push(_xl, _xr, _y, _dir: LongInt);

begin

    if checkFails(Stack.Count <= 8192, 'FillLand: stack overflow', true) then exit;

    _y:= _y + _dir;

    if (_y < 0) or (_y >= LAND_HEIGHT) then

        exit;

    with Stack.points[Stack.Count] do

        begin

        xl:= _xl;

        xr:= _xr;

        y:= _y;

        dir:= _dir

        end;

    inc(Stack.Count)

end;

procedure Pop(var _xl, _xr, _y, _dir: LongInt);

begin

    dec(Stack.Count);

    with Stack.points[Stack.Count] do

        begin

        _xl:= xl;

        _xr:= xr;

        _y:= y;

        _dir:= dir

        end

end;

procedure DrawEdge(var pa: TPixAr; value: Word);

var i: LongInt;

begin

    i:= 0;

    with pa do

        while i < LongInt(Count) - 1 do

            if (ar[i + 1].X = NTPX) then

                inc(i, 2)

            else

                begin

                DrawLine(ar[i].x, ar[i].y, ar[i + 1].x, ar[i + 1].y, value);

                inc(i)

                end

end;

procedure Vector(p1, p2, p3: TPoint; var Vx, Vy: hwFloat);

var d1, d2, d: hwFloat;

begin

    Vx:= int2hwFloat(p1.X - p3.X);

    Vy:= int2hwFloat(p1.Y - p3.Y);

    d2:= Distance(Vx, Vy);

    if d2.QWordValue = 0 then

        begin

        Vx:= _0;

        Vy:= _0

        end

    else

        begin

        d:= DistanceI(p2.X - p1.X, p2.Y - p1.Y);

        d1:= DistanceI(p2.X - p3.X, p2.Y - p3.Y);

        if d1 < d then

            d:= d1;

        if d2 < d then

            d:= d2;

        d2:= d * _1div3 / d2;

        Vx:= Vx * d2;

        Vy:= Vy * d2

        end

end;

procedure AddLoopPoints(var pa, opa: TPixAr; StartI, EndI: LongInt; Delta: hwFloat);

var i, pi, ni: LongInt;

    NVx, NVy, PVx, PVy: hwFloat;

    x1, x2, y1, y2: LongInt;

    tsq, tcb, t, r1, r2, r3, cx1, cx2, cy1, cy2: hwFloat;

    X, Y: LongInt;

begin

    if pa.Count < cMaxEdgePoints - 2 then

        begin

        pi:= EndI;

        i:= StartI;

        ni:= Succ(StartI);

        {$HINTS OFF}

        Vector(opa.ar[pi], opa.ar[i], opa.ar[ni], NVx, NVy);

        {$HINTS ON}

        repeat

            i:= ni;

            inc(pi);

            if pi > EndI then

                pi:= StartI;

            inc(ni);

            if ni > EndI then

                ni:= StartI;

            PVx:= NVx;

            PVy:= NVy;

            Vector(opa.ar[pi], opa.ar[i], opa.ar[ni], NVx, NVy);

            x1:= opa.ar[pi].x;

            y1:= opa.ar[pi].y;

            x2:= opa.ar[i].x;

            y2:= opa.ar[i].y;

            cx1:= int2hwFloat(x1) - PVx;

            cy1:= int2hwFloat(y1) - PVy;

            cx2:= int2hwFloat(x2) + NVx;

            cy2:= int2hwFloat(y2) + NVy;

            t:= _0;

            while (t.Round = 0) and (pa.Count < cMaxEdgePoints-2) do

                begin

                tsq:= t * t;

                tcb:= tsq * t;

                r1:= (_1 - t*3 + tsq*3 - tcb);

                r2:= (     t*3 - tsq*6 + tcb*3);

                r3:= (           tsq*3 - tcb*3);

                X:= hwRound(r1 * x1 + r2 * cx1 + r3 * cx2 + tcb * x2);

                Y:= hwRound(r1 * y1 + r2 * cy1 + r3 * cy2 + tcb * y2);

                t:= t + Delta;

                pa.ar[pa.Count].x:= X;

                pa.ar[pa.Count].y:= Y;

                inc(pa.Count);

                //TryDo(pa.Count <= cMaxEdgePoints, 'Edge points overflow', true)

                end;

        until i = StartI;

        end;

    pa.ar[pa.Count].x:= opa.ar[StartI].X;

    pa.ar[pa.Count].y:= opa.ar[StartI].Y;

    inc(pa.Count)

end;

procedure BezierizeEdge(var pa: TPixAr; Delta: hwFloat);

var i, StartLoop: LongInt;

    opa: TPixAr;

begin

opa:= pa;

pa.Count:= 0;

i:= 0;

StartLoop:= 0;

while (i < LongInt(opa.Count)) and (pa.Count < cMaxEdgePoints-1) do

    if (opa.ar[i + 1].X = NTPX) then

        begin

        AddLoopPoints(pa, opa, StartLoop, i, Delta);

        inc(i, 2);

        StartLoop:= i;

        pa.ar[pa.Count].X:= NTPX;

        pa.ar[pa.Count].Y:= 0;

        inc(pa.Count);

        end else inc(i)

end;

end.