(*

 * Hedgewars, a free turn based strategy game

 * Copyright (c) 2004-2011 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 AddGearCI(Gear: PGear);

procedure DeleteCI(Gear: PGear);

function  CheckGearsCollision(Gear: PGear): PGearArray;

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

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

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

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

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

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

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

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

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  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 AddGearCI(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);

    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 DeleteGear(t)

    end;

end;

procedure DeleteCI(Gear: PGear);

begin

if Gear^.CollisionIndex >= 0 then

    begin

    with cinfos[Gear^.CollisionIndex] do

        ChangeRoundInLand(X, Y, Radius - 1, false);

    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): boolean;

var x, y, i: LongInt;

    TestWord: LongWord;

begin

if Gear^.IntersectGear <> nil then

   with Gear^ do

        if (hwRound(IntersectGear^.X) + IntersectGear^.Radius < hwRound(X) - Radius) or

           (hwRound(IntersectGear^.X) - IntersectGear^.Radius > hwRound(X) + Radius) then

           begin

           IntersectGear:= nil;

           TestWord:= 0

           end else

           TestWord:= 255

   else TestWord:= 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] > TestWord then exit(true);

     inc(y)

   until (y > i);

   end;

TestCollisionXwithGear:= false

end;

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

var x, y, i: LongInt;

    TestWord: LongWord;

begin

if Gear^.IntersectGear <> nil then

   with Gear^ do

        if (hwRound(IntersectGear^.Y) + IntersectGear^.Radius < hwRound(Y) - Radius) or

           (hwRound(IntersectGear^.Y) - IntersectGear^.Radius > hwRound(Y) + Radius) then

           begin

           IntersectGear:= nil;

           TestWord:= 0

           end else

           TestWord:= 255

   else TestWord:= 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] > TestWord then exit(Land[y, x]);

     inc(x)

   until (x > i);

   end;

TestCollisionYwithGear:= 0

end;

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

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

    flag: boolean;

begin

flag:= false;

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] > 255 then exit(true)

           else if Land[y, x] <> 0 then flag:= true;

     inc(y)

   until (y > i);

   end;

TestCollisionXKick:= flag;

if flag 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

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

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

         if ((cGear^.Kind in [gtHedgehog, gtMine]) 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)) then

             begin

             with cGear^ do

                  begin

                  dX:= Gear^.dX;

                  dY:= Gear^.dY * _0_5;

                  State:= State or gstMoving;

                  Active:= true

                  end;

             DeleteCI(cGear);

             exit(false)

             end

   end

end;

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

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

    flag: boolean;

begin

flag:= false;

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] > 255 then exit(true)

           else if Land[y, x] <> 0 then flag:= true;

     inc(x)

   until (x > i);

   end;

TestCollisionYKick:= flag;

if flag then

   begin

   if hwAbs(Gear^.dY) < cHHKick then exit(true);

   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);

   for i:= 0 to Pred(Count) do

    with cinfos[i] do

      if (Gear <> cGear) and

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

         ((my > y) xor (Dir > 0)) then

         if (cGear^.Kind in [gtHedgehog, gtMine, gtExplosives]) and ((Gear^.State and gstNotKickable) = 0) 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;

                  Active:= true

                  end;

             DeleteCI(cGear);

             exit(false)

             end

   end

end;

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

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): boolean;

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] > 255 then exit(true);

     inc(y)

   until (y > i);

   end;

TestCollisionX:= false

end;

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

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] > 255 then exit(true);

     inc(x)

   until (x > i);

   end;

TestCollisionY:= false

end;

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

begin

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

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

if withGear then TestCollisionYwithXYShift:= TestCollisionYwithGear(Gear, Dir) <> 0

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

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(true);

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(true);

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

    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;

            if (((tmpy) and LAND_HEIGHT_MASK) = 0) and (((tmpx) and LAND_WIDTH_MASK) = 0) then

                if (Land[tmpy,tmpx] > TestWord) then

                    begin

                    // remember the index belonging to the first and last collision (if in 1st half)

                    if (i <> 0) then

                        begin

                        if (ri = -1) then

                            ri:= i

                        else

                            li:= i;

                        end;

                    end;

            end;

        if i = 7 then break;

        // prepare offset for next check (clockwise)

        if (mx = -1) and (my <> -1) then my:= my - 1

        else if (my = -1) and (mx <> 1) then mx:= mx + 1

        else if (mx = 1) and (my <> 1) then my:= my + 1

        else mx:= mx - 1;

        end;

    ldx:= collisionX;

    ldy:= collisionY;

    rdx:= collisionX;

    rdy:= collisionY;

    // edge-crawl

    for i:= 0 to 8 do

        begin

        // using mx,my as temporary value buffer here

        jfr:= 8+li+1;

        jto:= 8+li-1;

        isColl:= false;

        for j:= jfr downto jto do

            begin

            tmpo:= j mod 8;

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

            for k:= 3 downto 1 do

                begin

                tmpx:= ldx + k * offset[tmpo,0];

                tmpy:= ldy + k * offset[tmpo,1];

                if (((tmpy) and LAND_HEIGHT_MASK) = 0) and (((tmpx) and LAND_WIDTH_MASK)  = 0)

                    and (Land[tmpy,tmpx] > TestWord) then

                        begin

                        ldx:= tmpx;

                        ldy:= tmpy;