{$INCLUDE "options.inc"}

unit uLandGenPerlin;

interface

procedure GenPerlin;

implementation

var p: array[0..511] of LongInt;

const fadear: array[byte] of LongInt = 

(0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 3, 3, 4, 6, 7, 9, 10, 12,

14, 17, 19, 22, 25, 29, 32, 36, 40, 45, 49, 54, 60, 65, 71,

77, 84, 91, 98, 105, 113, 121, 130, 139, 148, 158, 167, 178,

188, 199, 211, 222, 234, 247, 259, 273, 286, 300, 314, 329, 344,

359, 374, 390, 407, 424, 441, 458, 476, 494, 512, 531, 550,

570, 589, 609, 630, 651, 672, 693, 715, 737, 759, 782, 805, 828,

851, 875, 899, 923, 948, 973, 998, 1023, 1049, 1074, 1100, 1127,

1153, 1180, 1207, 1234, 1261, 1289, 1316, 1344, 1372, 1400, 1429,

1457, 1486, 1515, 1543, 1572, 1602, 1631, 1660, 1690, 1719, 1749,

1778, 1808, 1838, 1868, 1898, 1928, 1958, 1988, 2018, 2048, 2077,

2107, 2137, 2167, 2197, 2227, 2257, 2287, 2317, 2346, 2376, 2405,

2435, 2464, 2493, 2523, 2552, 2580, 2609, 2638, 2666, 2695, 2723,

2751, 2779, 2806, 2834, 2861, 2888, 2915, 2942, 2968, 2995, 3021,

3046, 3072, 3097, 3122, 3147, 3172, 3196, 3220, 3244, 3267, 3290,

3313, 3336, 3358, 3380, 3402, 3423, 3444, 3465, 3486, 3506, 3525,

3545, 3564, 3583, 3601, 3619, 3637, 3654, 3672, 3688, 3705, 3721,

3736, 3751, 3766, 3781, 3795, 3809, 3822, 3836, 3848, 3861, 3873,

3884, 3896, 3907, 3917, 3928, 3937, 3947, 3956, 3965, 3974, 3982,

3990, 3997, 4004, 4011, 4018, 4024, 4030, 4035, 4041, 4046, 4050,

4055, 4059, 4063, 4066, 4070, 4073, 4076, 4078, 4081, 4083, 4085,

4086, 4088, 4089, 4091, 4092, 4092, 4093, 4094, 4094, 4095, 4095,

4095, 4095, 4095, 4095, 4095);

function fade(t: LongInt) : LongInt; inline;

var t0, t1: LongInt;

begin

    t0:= fadear[t shr 8];

    fade:= t0 + ((t and 255) * (t1 - t0) shr 8)

end;

function lerp(t, a, b: LongInt) : LongInt; inline;

begin

    lerp:= a + (t * (b - a) shr 12)

end;

function grad(hash, x, y: LongInt) : LongInt; inline;

var h, v, u: LongInt;

begin

    h:= hash and 15;

    if h < 8 then u:= x else u:= y;

    if h < 4 then v:= y else

        if (h = 12) or (h = 14) then v:= x else v:= 0;

    if (h and 1) <> 0 then u:= -u;

    if (h and 2) <> 0 then v:= -v;

    grad:= u + v

end;

function inoise(x, y: LongInt) : LongInt; inline;

const N = $10000;

var xx, yy, u, v, A, AA, AB, B, BA, BB: LongInt;

begin

    xx:= (x shr 16) and 255;

    yy:= (y shr 16) and 255;

    x:= x and $FFFF;

    y:= y and $FFFF;

    u:= fade(x);

    v:= fade(y);

    A:= p[xx    ] + yy; AA:= p[A]; AB:= p[A + 1];

    B:= p[xx + 1] + yy; BA:= p[B]; BB:= p[B + 1];

    inoise:=

            lerp(v, lerp(u, grad(p[AA  ], x   , y  ),

                            grad(p[BA  ], x-N , y  )),

                    lerp(u, grad(p[AB  ], x   , y-N),

                            grad(p[BB  ], x-N , y-N)));

end;

function f(t: double): double; inline;

begin

    f:= t * t * t * (t * (t * 6 - 15) + 10);

end;

procedure inoise_setup();

var i, ii, t: LongInt;

begin

    for i:= 0 to 254 do

        p[i]:= i + 1;

    p[255]:= 0;

    for i:= 0 to 254 do

    begin

        ii:= GetRandom(256 - i) + i;

        t:= p[i];

        p[i]:= p[ii];

        p[ii]:= t

    end;

    for i:= 0 to 255 do

        p[256 + i]:= p[i];

end;

const detail = 120000*3;

    field = 3;

    df = detail * field;

    width = 4096;

    height = 2048;

    bottomPlateHeight = 90;

    bottomPlateMargin = 1200;

    plateFactor = 1;

procedure GenPerlin;

var y, x, dy, di, dj, r: LongInt;

begin

    inoise_setup();

    for y:= 1024 to pred(height) do

    begin

        di:= df * y div height;

        for x:= 0 to pred(width) do

        begin

            dj:= df * x div width;

            r:= (abs(inoise(di, dj))) shr 8 and $ff;

            //r:= r - max(0, abs(x - width div 2) - width * 55 div 128); // fade on edges

            //r:= r - max(0, - abs(x - width div 2) + width * 2 div 100); // split vertically in the middle

            //r:= r + (trunc(1000 - sqrt(sqr(x - (width div 2)) * 4 + sqr(y - height * 5 div 4) * 22))) div 600 * 20; // ellipse

            r:= r + (trunc(2000 - (abs(x - (width div 2)) * 2 + abs(y - height * 5 div 4) * 4))) div 26; // manhattan length ellipse

            if (y > height - bottomPlateHeight) and (x > bottomPlateMargin) and (x + bottomPlateMargin < width) then

            begin

                dy:= (y - height + bottomPlateHeight) * plateFactor;

                r:= r + dy;

                if x < bottomPlateMargin + bottomPlateHeight then

                    r:= r + (x - bottomPlateMargin - bottomPlateHeight) * plateFactor

                else

                if x + bottomPlateMargin + bottomPlateHeight > width then

                    r:= r - (x - width + bottomPlateMargin + bottomPlateHeight) * plateFactor;

            end;

        end;

    end;

    leftX:= 0;

    rightX:= 4095;

    topY:= 0;

    hasBorder:= false;

end;

end.