(*

 * Hedgewars, a free turn based strategy game

 * Copyright (c) 2004-2013 Andrey Korotaev <unC0Rr@gmail.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; version 2 of the License

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA

 *)

{$INCLUDE "options.inc"}

unit uCollisions;

interface

uses uFloat, uTypes;

const cMaxGearArrayInd = 1023;

type PGearArray = ^TGearArray;

    TGearArray = record

        ar: array[0..cMaxGearArrayInd] of PGear;

        Count: Longword

        end;

procedure initModule;

procedure freeModule;

procedure AddCI(Gear: PGear);

procedure DeleteCI(Gear: PGear);

function  CheckGearsCollision(Gear: PGear): PGearArray;

function  TestCollisionXwithGear(Gear: PGear; Dir: LongInt): Word;

function  TestCollisionYwithGear(Gear: PGear; Dir: LongInt): Word;

function  TestCollisionXKick(Gear: PGear; Dir: LongInt): Word;

function  TestCollisionYKick(Gear: PGear; Dir: LongInt): Word;

function  TestCollisionX(Gear: PGear; Dir: LongInt): Word;

function  TestCollisionY(Gear: PGear; Dir: LongInt): Word;

function  TestCollisionXwithXYShift(Gear: PGear; ShiftX: hwFloat; ShiftY: LongInt; Dir: LongInt): Word; inline;

function  TestCollisionXwithXYShift(Gear: PGear; ShiftX: hwFloat; ShiftY: LongInt; Dir: LongInt; withGear: boolean): Word;

function  TestCollisionYwithXYShift(Gear: PGear; ShiftX, ShiftY: LongInt; Dir: LongInt): Word; inline;

function  TestCollisionYwithXYShift(Gear: PGear; ShiftX, ShiftY: LongInt; Dir: LongInt; withGear: boolean): Word;

function  TestRectancleForObstacle(x1, y1, x2, y2: LongInt; landOnly: boolean): boolean;

// returns: negative sign if going downhill to left, value is steepness (noslope/error = _0, 45° = _0_5)

function  CalcSlopeBelowGear(Gear: PGear): hwFloat;

function  CalcSlopeNearGear(Gear: PGear; dirX, dirY: LongInt): hwFloat;

function  CalcSlopeTangent(Gear: PGear; collisionX, collisionY: LongInt; var outDeltaX, outDeltaY: LongInt; TestWord: LongWord): boolean;

implementation

type TCollisionEntry = record

    X, Y, Radius: LongInt;

    cGear: PGear;

    end;

const MAXRECTSINDEX = 1023;

var Count: Longword;

    cinfos: array[0..MAXRECTSINDEX] of TCollisionEntry;

    ga: TGearArray;

procedure AddCI(Gear: PGear);

var t: PGear;

begin

if Gear^.CollisionIndex >= 0 then

    exit;

TryDo(Count <= MAXRECTSINDEX, 'Collision rects array overflow', true);

with cinfos[Count] do

    begin

    X:= hwRound(Gear^.X);

    Y:= hwRound(Gear^.Y);

    Radius:= Gear^.Radius;

    ChangeRoundInLand(X, Y, Radius - 1, true, (Gear = CurrentHedgehog^.Gear) or ((Gear^.Kind = gtCase) and (Gear^.State and gstFrozen = 0)));

    cGear:= Gear

    end;

Gear^.CollisionIndex:= Count;

inc(Count);

// mines are the easiest way to overflow collision

if (Count > (MAXRECTSINDEX-20)) then

    begin

    t:= GearsList;

    while (t <> nil) and (t^.Kind <> gtMine) do 

        t:= t^.NextGear;

    if (t <> nil) then

        t^.State:= t^.State or gmDelete

    end;

end;

procedure DeleteCI(Gear: PGear);

begin

if Gear^.CollisionIndex >= 0 then

    begin

    with cinfos[Gear^.CollisionIndex] do

        ChangeRoundInLand(X, Y, Radius - 1, false, (Gear = CurrentHedgehog^.Gear) or ((Gear^.Kind = gtCase) and (Gear^.State and gstFrozen = 0)));

    cinfos[Gear^.CollisionIndex]:= cinfos[Pred(Count)];

    cinfos[Gear^.CollisionIndex].cGear^.CollisionIndex:= Gear^.CollisionIndex;

    Gear^.CollisionIndex:= -1;

    dec(Count)

    end;

end;

function CheckGearsCollision(Gear: PGear): PGearArray;

var mx, my, tr: LongInt;

    i: Longword;

begin

CheckGearsCollision:= @ga;

ga.Count:= 0;

if Count = 0 then

    exit;

mx:= hwRound(Gear^.X);

my:= hwRound(Gear^.Y);

tr:= Gear^.Radius + 2;

for i:= 0 to Pred(Count) do

    with cinfos[i] do

        if (Gear <> cGear) and

            (sqr(mx - x) + sqr(my - y) <= sqr(Radius + tr)) then

                begin

                ga.ar[ga.Count]:= cinfos[i].cGear;

                inc(ga.Count)

                end

end;

function TestCollisionXwithGear(Gear: PGear; Dir: LongInt): Word;

var x, y, i: LongInt;

begin

// Special case to emulate the old intersect gear clearing, but with a bit of slop for pixel overlap

if (Gear^.CollisionMask = lfNotCurrentMask) and (Gear^.Kind <> gtHedgehog) and (Gear^.Hedgehog <> nil) and (Gear^.Hedgehog^.Gear <> nil) and

    ((hwRound(Gear^.Hedgehog^.Gear^.X) + Gear^.Hedgehog^.Gear^.Radius + 16 < hwRound(Gear^.X) - Gear^.Radius) or

     (hwRound(Gear^.Hedgehog^.Gear^.X) - Gear^.Hedgehog^.Gear^.Radius - 16 > hwRound(Gear^.X) + Gear^.Radius)) then

    Gear^.CollisionMask:= $FFFF;

x:= hwRound(Gear^.X);

if Dir < 0 then

    x:= x - Gear^.Radius

else

    x:= x + Gear^.Radius;

if (x and LAND_WIDTH_MASK) = 0 then

    begin

    y:= hwRound(Gear^.Y) - Gear^.Radius + 1;

    i:= y + Gear^.Radius * 2 - 2;

    repeat

        if (y and LAND_HEIGHT_MASK) = 0 then

            if Land[y, x] and Gear^.CollisionMask <> 0 then

                exit(Land[y, x] and Gear^.CollisionMask);

        inc(y)

    until (y > i);

    end;

TestCollisionXwithGear:= 0

end;

function TestCollisionYwithGear(Gear: PGear; Dir: LongInt): Word;

var x, y, i: LongInt;

begin

// Special case to emulate the old intersect gear clearing, but with a bit of slop for pixel overlap

if (Gear^.CollisionMask = lfNotCurrentMask) and (Gear^.Kind <> gtHedgehog) and (Gear^.Hedgehog <> nil) and (Gear^.Hedgehog^.Gear <> nil) and

    ((hwRound(Gear^.Hedgehog^.Gear^.Y) + Gear^.Hedgehog^.Gear^.Radius + 16 < hwRound(Gear^.Y) - Gear^.Radius) or

     (hwRound(Gear^.Hedgehog^.Gear^.Y) - Gear^.Hedgehog^.Gear^.Radius - 16 > hwRound(Gear^.Y) + Gear^.Radius)) then

    Gear^.CollisionMask:= $FFFF;

y:= hwRound(Gear^.Y);

if Dir < 0 then

    y:= y - Gear^.Radius

else

    y:= y + Gear^.Radius;

if (y and LAND_HEIGHT_MASK) = 0 then

    begin

    x:= hwRound(Gear^.X) - Gear^.Radius + 1;

    i:= x + Gear^.Radius * 2 - 2;

    repeat

        if (x and LAND_WIDTH_MASK) = 0 then

            if Land[y, x] and Gear^.CollisionMask <> 0 then

                begin

                exit(Land[y, x] and Gear^.CollisionMask)

                end;

        inc(x)

    until (x > i);

    end;

TestCollisionYwithGear:= 0

end;

function TestCollisionXKick(Gear: PGear; Dir: LongInt): Word;

var x, y, mx, my, i: LongInt;

    pixel: Word;

begin

pixel:= 0;

x:= hwRound(Gear^.X);

if Dir < 0 then

    x:= x - Gear^.Radius

else

    x:= x + Gear^.Radius;

if (x and LAND_WIDTH_MASK) = 0 then

    begin

    y:= hwRound(Gear^.Y) - Gear^.Radius + 1;

    i:= y + Gear^.Radius * 2 - 2;

    repeat

        if (y and LAND_HEIGHT_MASK) = 0 then

            if Land[y, x] and Gear^.CollisionMask > 255 then

                exit(Land[y, x] and Gear^.CollisionMask)

            else if Land[y, x] and Gear^.CollisionMask <> 0 then

                pixel:= Land[y, x] and Gear^.CollisionMask;

    inc(y)

    until (y > i);

    end;

TestCollisionXKick:= pixel;

if pixel <> 0 then

    begin

    if hwAbs(Gear^.dX) < cHHKick then

        exit;

    if (Gear^.State and gstHHJumping <> 0)

    and (hwAbs(Gear^.dX) < _0_4) then

        exit;

    mx:= hwRound(Gear^.X);

    my:= hwRound(Gear^.Y);

    for i:= 0 to Pred(Count) do

        with cinfos[i] do

            if  (Gear <> cGear) and 

                ((mx > x) xor (Dir > 0)) and

                (

                  ((cGear^.Kind in [gtHedgehog, gtMine, gtKnife]) and ((Gear^.State and gstNotKickable) = 0)) or

                // only apply X kick if the barrel is knocked over

                  ((cGear^.Kind = gtExplosives) and ((cGear^.State and gsttmpflag) <> 0))

                ) and

                (sqr(mx - x) + sqr(my - y) <= sqr(Radius + Gear^.Radius + 2)) then

                    begin

                    with cGear^ do

                        begin

                        dX:= Gear^.dX;

                        dY:= Gear^.dY * _0_5;

                        State:= State or gstMoving;

                        if Kind = gtKnife then State:= State and (not gstCollision);

                        Active:= true

                        end;

                    DeleteCI(cGear);

                    exit(0);

                    end

    end

end;

function TestCollisionYKick(Gear: PGear; Dir: LongInt): Word;

var x, y, mx, my,  myr, i: LongInt;

    pixel: Word;

begin

pixel:= 0;

y:= hwRound(Gear^.Y);

if Dir < 0 then

    y:= y - Gear^.Radius

else

    y:= y + Gear^.Radius;

if (y and LAND_HEIGHT_MASK) = 0 then

    begin

    x:= hwRound(Gear^.X) - Gear^.Radius + 1;

    i:= x + Gear^.Radius * 2 - 2;

    repeat

    if (x and LAND_WIDTH_MASK) = 0 then

        if Land[y, x] > 0 then

            if Land[y, x] and Gear^.CollisionMask > 255 then

                exit(Land[y, x] and Gear^.CollisionMask)

            else if Land[y, x] <> 0 then

                pixel:= Land[y, x] and Gear^.CollisionMask;

    inc(x)

    until (x > i);

    end;

TestCollisionYKick:= pixel;

if pixel <> 0 then

    begin

    if hwAbs(Gear^.dY) < cHHKick then

        exit;

    if (Gear^.State and gstHHJumping <> 0) and (not Gear^.dY.isNegative) and (Gear^.dY < _0_4) then

        exit;

    mx:= hwRound(Gear^.X);

    my:= hwRound(Gear^.Y);

    myr:= my+Gear^.Radius;

    for i:= 0 to Pred(Count) do

        with cinfos[i] do

            if (Gear <> cGear) and

               ((myr > y) xor (Dir > 0)) and

               (Gear^.State and gstNotKickable = 0) and

               (cGear^.Kind in [gtHedgehog, gtMine, gtKnife, gtExplosives]) and 

               (sqr(mx - x) + sqr(my - y) <= sqr(Radius + Gear^.Radius + 2)) then

                    begin

                    with cGear^ do

                        begin

                        if (Kind <> gtExplosives) or ((State and gsttmpflag) <> 0) then

                            dX:= Gear^.dX * _0_5;

                        dY:= Gear^.dY;

                        State:= State or gstMoving;

                        if Kind = gtKnife then State:= State and (not gstCollision);

                        Active:= true

                        end;

                    DeleteCI(cGear);

                    exit(0)

                    end

    end

end;

function TestCollisionXwithXYShift(Gear: PGear; ShiftX: hwFloat; ShiftY: LongInt; Dir: LongInt): Word; inline;

begin

    TestCollisionXwithXYShift:= TestCollisionXwithXYShift(Gear, ShiftX, ShiftY, Dir, true);

end;

function TestCollisionXwithXYShift(Gear: PGear; ShiftX: hwFloat; ShiftY: LongInt; Dir: LongInt; withGear: boolean): Word;

begin

Gear^.X:= Gear^.X + ShiftX;

Gear^.Y:= Gear^.Y + int2hwFloat(ShiftY);

if withGear then 

    TestCollisionXwithXYShift:= TestCollisionXwithGear(Gear, Dir)

else TestCollisionXwithXYShift:= TestCollisionX(Gear, Dir);

Gear^.X:= Gear^.X - ShiftX;

Gear^.Y:= Gear^.Y - int2hwFloat(ShiftY)

end;

function TestCollisionX(Gear: PGear; Dir: LongInt): Word;

var x, y, i: LongInt;

begin

x:= hwRound(Gear^.X);

if Dir < 0 then

    x:= x - Gear^.Radius

else

    x:= x + Gear^.Radius;

if (x and LAND_WIDTH_MASK) = 0 then

    begin

    y:= hwRound(Gear^.Y) - Gear^.Radius + 1;

    i:= y + Gear^.Radius * 2 - 2;

    repeat

        if (y and LAND_HEIGHT_MASK) = 0 then

            if Land[y, x] and Gear^.CollisionMask > 255 then

                exit(Land[y, x] and Gear^.CollisionMask);

    inc(y)

    until (y > i);

    end;

TestCollisionX:= 0

end;

function TestCollisionY(Gear: PGear; Dir: LongInt): Word;

var x, y, i: LongInt;

begin

y:= hwRound(Gear^.Y);

if Dir < 0 then

    y:= y - Gear^.Radius

else

    y:= y + Gear^.Radius;

if (y and LAND_HEIGHT_MASK) = 0 then

    begin

    x:= hwRound(Gear^.X) - Gear^.Radius + 1;

    i:= x + Gear^.Radius * 2 - 2;

    repeat

        if (x and LAND_WIDTH_MASK) = 0 then

            if Land[y, x] and Gear^.CollisionMask > 255 then

                exit(Land[y, x] and Gear^.CollisionMask);

    inc(x)

    until (x > i);

    end;

TestCollisionY:= 0

end;

function TestCollisionYwithXYShift(Gear: PGear; ShiftX, ShiftY: LongInt; Dir: LongInt): Word; inline;

begin

    TestCollisionYwithXYShift:= TestCollisionYwithXYShift(Gear, ShiftX, ShiftY, Dir, true);

end;

function TestCollisionYwithXYShift(Gear: PGear; ShiftX, ShiftY: LongInt; Dir: LongInt; withGear: boolean): Word;

begin

Gear^.X:= Gear^.X + int2hwFloat(ShiftX);

Gear^.Y:= Gear^.Y + int2hwFloat(ShiftY);

if withGear then

  TestCollisionYwithXYShift:= TestCollisionYwithGear(Gear, Dir)

else

  TestCollisionYwithXYShift:= TestCollisionY(Gear, Dir);

Gear^.X:= Gear^.X - int2hwFloat(ShiftX);

Gear^.Y:= Gear^.Y - int2hwFloat(ShiftY)

end;

function TestRectancleForObstacle(x1, y1, x2, y2: LongInt; landOnly: boolean): boolean;

var x, y: LongInt;

    TestWord: LongWord;

begin

TestRectancleForObstacle:= true;

if landOnly then

    TestWord:= 255

else

    TestWord:= 0;

if x1 > x2 then

begin

    x  := x1;

    x1 := x2;

    x2 := x;

end;

if y1 > y2 then

begin

    y  := y1;

    y1 := y2;

    y2 := y;

end;

if (hasBorder and ((y1 < 0) or (x1 < 0) or (x2 > LAND_WIDTH))) then

    exit;

for y := y1 to y2 do

    for x := x1 to x2 do

        if ((y and LAND_HEIGHT_MASK) = 0) and ((x and LAND_WIDTH_MASK) = 0) and (Land[y, x] > TestWord) then

            exit;

TestRectancleForObstacle:= false

end;

function CalcSlopeTangent(Gear: PGear; collisionX, collisionY: LongInt; var outDeltaX, outDeltaY: LongInt; TestWord: LongWord): boolean;

var ldx, ldy, rdx, rdy: LongInt;

    i, j, k, mx, my, li, ri, jfr, jto, tmpo : ShortInt;

    tmpx, tmpy: LongWord;

    dx, dy, s: hwFloat;

    offset: array[0..7,0..1] of ShortInt;

    isColl: Boolean;

begin

    CalcSlopeTangent:= false;

    dx:= Gear^.dX;

    dy:= Gear^.dY;

    // we start searching from the direction the gear came from

    if (dx.QWordValue > _0_995.QWordValue )

    or (dy.QWordValue > _0_995.QWordValue ) then

        begin // scale

        s := _0_995 / Distance(dx,dy);

        dx := s * dx;

        dy := s * dy;

        end;

    mx:= hwRound(Gear^.X-dx) - hwRound(Gear^.X);

    my:= hwRound(Gear^.Y-dy) - hwRound(Gear^.Y);

    li:= -1;

    ri:= -1;

    // go around collision pixel, checking for first/last collisions

    // this will determinate what angles will be tried to crawl along

    for i:= 0 to 7 do

        begin

        offset[i,0]:= mx;

        offset[i,1]:= my;

        // multiplicator k tries to skip small pixels/gaps when possible

        for k:= 4 downto 1 do

            begin

            tmpx:= collisionX + k * mx;

            tmpy:= collisionY + k * my;