(*

 * Hedgewars, a free turn based strategy game

 * Copyright (c) 2005-2010 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 uGears, uFloat;

const cMaxGearArrayInd = 255;

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): boolean;

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

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

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

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

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

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

implementation

uses uMisc, uConsts, uLand, uLandGraphics;

type TCollisionEntry = record

            X, Y, Radius: LongInt;

            cGear: PGear;

            end;

const MAXRECTSINDEX = 511;

var Count: Longword;

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

    ga: TGearArray;

procedure AddGearCI(Gear: 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;

    end;

Gear^.CollisionIndex:= Count;

inc(Count)

end;

procedure DeleteCI(Gear: PGear);

begin

if Gear^.CollisionIndex >= 0 then

    begin

    with cinfos[Gear^.CollisionIndex] do

    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;

    i: Longword;

begin

CheckGearsCollision:= @ga;

ga.Count:= 0;

if Count = 0 then exit;

mx:= hwRound(Gear^.X);

my:= hwRound(Gear^.Y);

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): boolean;

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(true);

     inc(x)

   until (x > i);

   end;

TestCollisionYwithGear:= false

end;

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

    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);

end;

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

    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);

end;

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

begin

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

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

TestCollisionXwithXYShift:= TestCollisionXwithGear(Gear, Dir);

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

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

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): boolean;

begin

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

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

TestCollisionYwithXYShift:= TestCollisionYwithGear(Gear, Dir);

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

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

end;

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

var ldx, ldy, rdx, rdy: LongInt;

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

    tmpx, tmpy: LongWord;

    dx, dy, s: hwFloat;

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

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 := _1 / 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;

        tmpx:= collisionX + mx;

        tmpy:= collisionY + 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;

        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;

        for j:= jfr downto jto do

            begin

            tmpo:= j mod 8;

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

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

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

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

                    begin