hedgewars/uLandGraphics.pas
author koda
Sun, 17 Mar 2013 01:26:40 +0100
changeset 8739 bbab7e35eaf2
parent 8628 627e76986a08
child 8744 6c87486fd89b
permissions -rw-r--r--
less cryptic text insertion

(*
 * Hedgewars, a free turn based strategy game
 * Copyright (c) 2004-2012 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 uLandGraphics;
interface
uses uFloat, uConsts, uTypes;

type TRangeArray = array[0..31] of record
                                   Left, Right: LongInt;
                                   end;
     PRangeArray = ^TRangeArray;

function  addBgColor(OldColor, NewColor: LongWord): LongWord;
function  SweepDirty: boolean;
function  Despeckle(X, Y: LongInt): Boolean;
procedure Smooth(X, Y: LongInt);
function  CheckLandValue(X, Y: LongInt; LandFlag: Word): boolean;
function  DrawExplosion(X, Y, Radius: LongInt): Longword;
procedure DrawHLinesExplosions(ar: PRangeArray; Radius: LongInt; y, dY: LongInt; Count: Byte);
procedure DrawTunnel(X, Y, dX, dY: hwFloat; ticks, HalfWidth: LongInt);
procedure FillRoundInLand(X, Y, Radius: LongInt; Value: Longword);
procedure FillRoundInLandWithIce(X, Y, Radius: LongInt);
procedure ChangeRoundInLand(X, Y, Radius: LongInt; doSet, isCurrent: boolean);
function  LandBackPixel(x, y: LongInt): LongWord;
procedure DrawLine(X1, Y1, X2, Y2: LongInt; Color: Longword);
procedure DrawThickLine(X1, Y1, X2, Y2, radius: LongInt; color: Longword);
procedure DumpLandToLog(x, y, r: LongInt);
procedure DrawIceBreak(x, y, iceRadius, iceHeight: Longint);
function TryPlaceOnLand(cpX, cpY: LongInt; Obj: TSprite; Frame: LongInt; doPlace: boolean; indestructible: boolean): boolean;

implementation
uses SDLh, uLandTexture, uVariables, uUtils, uDebug;

function addBgColor(OldColor, NewColor: LongWord): LongWord;
// Factor ranges from 0 to 100% NewColor
var
    oRed, oBlue, oGreen, oAlpha, nRed, nBlue, nGreen, nAlpha: byte;
begin
    oAlpha := (OldColor shr AShift);
    nAlpha := (NewColor shr AShift);
    // shortcircuit
    if (oAlpha = 0) or (nAlpha = $FF) then
        begin
        addBgColor:= NewColor;
        exit
        end;
    // Get colors
    oRed   := (OldColor shr RShift);
    oGreen := (OldColor shr GShift);
    oBlue  := (OldColor shr BShift);

    nRed   := (NewColor shr RShift);
    nGreen := (NewColor shr GShift);
    nBlue  := (NewColor shr BShift);

    // Mix colors
    nRed   := min(255,((nRed*nAlpha) div 255) + ((oRed*oAlpha*byte(255-nAlpha)) div 65025));
    nGreen := min(255,((nGreen*nAlpha) div 255) + ((oGreen*oAlpha*byte(255-nAlpha)) div 65025));
    nBlue  := min(255,((nBlue*nAlpha) div 255) + ((oBlue*oAlpha*byte(255-nAlpha)) div 65025));
    nAlpha := min(255, oAlpha + nAlpha);

    addBgColor := (nAlpha shl AShift) or (nRed shl RShift) or (nGreen shl GShift) or (nBlue shl BShift);
end;

procedure FillCircleLines(x, y, dx, dy: LongInt; Value: Longword);
var i: LongInt;
begin
if ((y + dy) and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dx, 0) to Min(x + dx, LAND_WIDTH - 1) do
        if (Land[y + dy, i] and lfIndestructible) = 0 then
            Land[y + dy, i]:= Value;
if ((y - dy) and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dx, 0) to Min(x + dx, LAND_WIDTH - 1) do
        if (Land[y - dy, i] and lfIndestructible) = 0 then
            Land[y - dy, i]:= Value;
if ((y + dx) and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dy, 0) to Min(x + dy, LAND_WIDTH - 1) do
        if (Land[y + dx, i] and lfIndestructible) = 0 then
            Land[y + dx, i]:= Value;
if ((y - dx) and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dy, 0) to Min(x + dy, LAND_WIDTH - 1) do
        if (Land[y - dx, i] and lfIndestructible) = 0 then
            Land[y - dx, i]:= Value;
end;

procedure ChangeCircleLines(x, y, dx, dy: LongInt; doSet, isCurrent: boolean);
var i: LongInt;
begin
if not doSet then
    begin
    if ((y + dy) and LAND_HEIGHT_MASK) = 0 then
        for i:= Max(x - dx, 0) to Min(x + dx, LAND_WIDTH - 1) do
            if isCurrent then
                Land[y + dy, i]:= Land[y + dy, i] and $FF7F
            else if Land[y + dy, i] and $007F > 0 then
                Land[y + dy, i]:= (Land[y + dy, i] and $FF80) or ((Land[y + dy, i] and $7F) - 1);
    if ((y - dy) and LAND_HEIGHT_MASK) = 0 then
        for i:= Max(x - dx, 0) to Min(x + dx, LAND_WIDTH - 1) do
            if isCurrent then
                Land[y - dy, i]:= Land[y - dy, i] and $FF7F
            else if Land[y - dy, i] and $007F > 0 then
                Land[y - dy, i]:= (Land[y - dy, i] and $FF80) or ((Land[y - dy, i] and $7F) - 1);
    if ((y + dx) and LAND_HEIGHT_MASK) = 0 then
        for i:= Max(x - dy, 0) to Min(x + dy, LAND_WIDTH - 1) do
            if isCurrent then
                Land[y + dx, i]:= Land[y + dx, i] and $FF7F
            else if Land[y + dx, i] and $007F > 0 then
                Land[y + dx, i]:= (Land[y + dx, i] and $FF80) or ((Land[y + dx, i] and $7F) - 1);
    if ((y - dx) and LAND_HEIGHT_MASK) = 0 then
        for i:= Max(x - dy, 0) to Min(x + dy, LAND_WIDTH - 1) do
            if isCurrent then
                Land[y - dx, i]:= Land[y - dx, i] and $FF7F
            else if Land[y - dx, i] and $007F > 0 then
                Land[y - dx, i]:= (Land[y - dx, i] and $FF80) or ((Land[y - dx, i] and $7F) - 1)
    end
else
    begin
    if ((y + dy) and LAND_HEIGHT_MASK) = 0 then
        for i:= Max(x - dx, 0) to Min(x + dx, LAND_WIDTH - 1) do
            if isCurrent then
                Land[y + dy, i]:= Land[y + dy, i] or $80
            else if Land[y + dy, i] and $007F < 127 then
                Land[y + dy, i]:= (Land[y + dy, i] and $FF80) or ((Land[y + dy, i] and $7F) + 1);
    if ((y - dy) and LAND_HEIGHT_MASK) = 0 then
        for i:= Max(x - dx, 0) to Min(x + dx, LAND_WIDTH - 1) do
            if isCurrent then
                Land[y - dy, i]:= Land[y - dy, i] or $80
            else if Land[y - dy, i] and $007F < 127 then
                Land[y - dy, i]:= (Land[y - dy, i] and $FF80) or ((Land[y - dy, i] and $7F) + 1);
    if ((y + dx) and LAND_HEIGHT_MASK) = 0 then
        for i:= Max(x - dy, 0) to Min(x + dy, LAND_WIDTH - 1) do
            if isCurrent then
                Land[y + dx, i]:= Land[y + dx, i] or $80
            else if Land[y + dx, i] and $007F < 127 then
                Land[y + dx, i]:= (Land[y + dx, i] and $FF80) or ((Land[y + dx, i] and $7F) + 1);
    if ((y - dx) and LAND_HEIGHT_MASK) = 0 then
        for i:= Max(x - dy, 0) to Min(x + dy, LAND_WIDTH - 1) do
            if isCurrent then
                Land[y - dx, i]:= Land[y - dx, i] or $80
            else if Land[y - dx, i] and $007F < 127 then
                Land[y - dx, i]:= (Land[y - dx, i] and $FF80) or ((Land[y - dx, i] and $7F) + 1)
    end
end;



procedure FillRoundInLand(X, Y, Radius: LongInt; Value: Longword);
var dx, dy, d: LongInt;
begin
dx:= 0;
dy:= Radius;
d:= 3 - 2 * Radius;
while (dx < dy) do
    begin
    FillCircleLines(x, y, dx, dy, Value);
    if (d < 0) then
        d:= d + 4 * dx + 6
    else
        begin
        d:= d + 4 * (dx - dy) + 10;
        dec(dy)
        end;
    inc(dx)
    end;
if (dx = dy) then
    FillCircleLines(x, y, dx, dy, Value);
end;

procedure ChangeRoundInLand(X, Y, Radius: LongInt; doSet, isCurrent: boolean);
var dx, dy, d: LongInt;
begin
dx:= 0;
dy:= Radius;
d:= 3 - 2 * Radius;
while (dx < dy) do
    begin
    ChangeCircleLines(x, y, dx, dy, doSet, isCurrent);
    if (d < 0) then
        d:= d + 4 * dx + 6
    else
        begin
        d:= d + 4 * (dx - dy) + 10;
        dec(dy)
        end;
    inc(dx)
    end;
if (dx = dy) then
    ChangeCircleLines(x, y, dx, dy, doSet, isCurrent)
end;

procedure FillLandCircleLines0(x, y, dx, dy: LongInt);
var i, t: LongInt;
begin
t:= y + dy;
if (t and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dx, 0) to Min(x + dx, LAND_WIDTH - 1) do
        if ((Land[t, i] and lfIndestructible) = 0) and (not disableLandBack or (Land[t, i] > 255))  then
            if (cReducedQuality and rqBlurryLand) = 0 then
                LandPixels[t, i]:= 0
            else
                LandPixels[t div 2, i div 2]:= 0;

t:= y - dy;
if (t and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dx, 0) to Min(x + dx, LAND_WIDTH - 1) do
        if ((Land[t, i] and lfIndestructible) = 0) and (not disableLandBack or (Land[t, i] > 255))  then
            if (cReducedQuality and rqBlurryLand) = 0 then
                LandPixels[t, i]:= 0
            else
                LandPixels[t div 2, i div 2]:= 0;

t:= y + dx;
if (t and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dy, 0) to Min(x + dy, LAND_WIDTH - 1) do
        if ((Land[t, i] and lfIndestructible) = 0) and (not disableLandBack or (Land[t, i] > 255))  then
            if (cReducedQuality and rqBlurryLand) = 0 then
                LandPixels[t, i]:= 0
            else
                LandPixels[t div 2, i div 2]:= 0;

t:= y - dx;
if (t and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dy, 0) to Min(x + dy, LAND_WIDTH - 1) do
        if ((Land[t, i] and lfIndestructible) = 0) and (not disableLandBack or (Land[t, i] > 255))  then
            if (cReducedQuality and rqBlurryLand) = 0 then
                LandPixels[t, i]:= 0
            else
                LandPixels[t div 2, i div 2]:= 0;

end;


function isLandscapeEdge(weight:Longint):boolean; inline;
begin
    result := (weight < 8) and (weight >= 2);
end;

function getPixelWeight(x, y:Longint): Longint;
var
    i, j:Longint;
begin
    result := 0;
    for i := x - 1 to x + 1 do
        for j := y - 1 to y + 1 do
        begin
        if (i < 0) or
           (i > LAND_WIDTH - 1) or
           (j < 0) or
           (j > LAND_HEIGHT -1) then
           begin               
           result := 9;
           exit;
           end;

        if Land[j, i] and $FF00 and not lfIce = 0 then
           result := result + 1;
        end;
end;

procedure drawIcePixel(y, x:Longint);
var
    iceSurface: PSDL_Surface;
    icePixels: PLongwordArray;
    pictureX, pictureY: LongInt;
    w, c: LongWord;
    weight: Longint;
begin
    // So. 3 parameters here. Ice colour, Ice opacity, and a bias on the greyscaled pixel towards lightness
    iceSurface:= SpritesData[sprIceTexture].Surface;
    icePixels := iceSurface^.pixels;
    w:= LandPixels[y, x];
    if w > 0 then
        begin
        w:= round(((w shr RShift and $FF) * RGB_LUMINANCE_RED +
              (w shr BShift and $FF) * RGB_LUMINANCE_GREEN +
              (w shr GShift and $FF) * RGB_LUMINANCE_BLUE));
        if w < 128 then w:= w+128;
        if w > 255 then w:= 255;
        w:= (w shl RShift) or (w shl BShift) or (w shl GShift) or (LandPixels[y,x] and AMask);
        LandPixels[y, x]:= addBgColor(w, IceColor);
        LandPixels[y, x]:= addBgColor(LandPixels[y, x], icePixels^[iceSurface^.w * (y mod iceSurface^.h) + (x mod iceSurface^.w)])
        end
    else 
        begin
        LandPixels[y, x]:= IceColor and not AMask or $E8 shl AShift;
        LandPixels[y, x]:= addBgColor(LandPixels[y, x], icePixels^[iceSurface^.w * (y mod iceSurface^.h) + (x mod iceSurface^.w)]);
        // silly workaround to avoid having to make background erasure a tadb it smarter about sea ice
        if LandPixels[y, x] and AMask shr AShift = 255 then 
            LandPixels[y, x]:= LandPixels[y, x] and not AMask or 254 shl AShift;
        end;
end;

function getIncrementInquarter(dx, dy, quarter: Longint): Longint; inline;
const directionX : array [0..3] of Longint = (0, 0, 1, -1);
const directionY : array [0..3] of Longint = (1, -1, 0, 0);
begin
    getIncrementInquarter := directionX[quarter] * dx + directionY[quarter] * dy;
end;

function getIncrementInquarter2(dx, dy, quarter: Longint): Longint; inline;
const directionY : array [0..3] of Longint = (0, 0, 1, 1);
const directionX : array [0..3] of Longint = (1, 1, 0, 0);
begin
    getIncrementInquarter2 := directionX[quarter] * dx + directionY[quarter] * dy;
end;

procedure FillLandCircleLinesIce(x, y, dx, dy: LongInt);
var q, i, t, px, py: LongInt;
begin
for q := 0 to 3 do
    begin
    t:= y + getIncrementInquarter(dx, dy, q);
    if (t and LAND_HEIGHT_MASK) = 0 then
        for i:= Max(x - getIncrementInquarter2(dx, dy, q), 0) to Min(x + getIncrementInquarter2(dx, dy, q), LAND_WIDTH - 1) do
            if Land[t, i] and lfIce = 0 then
                begin
                if (cReducedQuality and rqBlurryLand) = 0 then
                    begin
                    px:= i; py:= t
                    end
                else
                    begin
                    px:= i div 2; py:= t div 2
                    end;
                if isLandscapeEdge(getPixelWeight(i, t)) then
                    begin
                    if (LandPixels[py, px] and AMask < 255) and (LandPixels[py, px] and AMask > 0) then
                        LandPixels[py, px] := (IceEdgeColor and not AMask) or (LandPixels[py, px] and AMask)
                    else if (LandPixels[py, px] and AMask < 255) or (Land[t, i] > 255) then
                        LandPixels[py, px] := IceEdgeColor
                    end
                else if Land[t, i] > 255 then
                    begin
                    drawIcePixel(py, px)
                    end;
                if Land[t, i] > 255 then Land[t, i] := Land[t, i] or lfIce and not lfDamaged;
                end;
    end
end;

procedure FillRoundInLandWithIce(X, Y, Radius: LongInt);
var dx, dy, d: LongInt;
    landRect: TSDL_Rect;
begin
dx:= 0;
dy:= Radius;
d:= 3 - 2 * Radius;
while (dx < dy) do
    begin
    FillLandCircleLinesIce(x, y, dx, dy);
    if (d < 0) then
        d:= d + 4 * dx + 6
    else
        begin
        d:= d + 4 * (dx - dy) + 10;
        dec(dy)
        end;
    inc(dx)
    end;
if (dx = dy) then
    FillLandCircleLinesIce(x, y, dx, dy);
landRect.x := min(max(x - Radius, 0), LAND_WIDTH - 1);
landRect.y := min(max(y - Radius, 0), LAND_HEIGHT - 1);
landRect.w := min(2*Radius, LAND_WIDTH - landRect.x - 1);
landRect.h := min(2*Radius, LAND_HEIGHT - landRect.y - 1);
UpdateLandTexture(landRect.x, landRect.w, landRect.y, landRect.h, true);        
end;


procedure DrawIceBreak(x, y, iceRadius, iceHeight: Longint);
var
    i, j: integer;
    landRect: TSDL_Rect;
begin
for i := min(max(x - iceRadius, 0), LAND_WIDTH - 1) to min(max(x + iceRadius, 0), LAND_WIDTH - 1) do
    begin
    for j := min(max(y, 0), LAND_HEIGHT - 1) to min(max(y + iceHeight, 0), LAND_HEIGHT - 1) do
        begin
        if Land[j, i] = 0 then
            begin
            Land[j, i] := lfIce;                
            drawIcePixel(j, i);
            end;
        end;        
    end;
landRect.x := min(max(x - iceRadius, 0), LAND_WIDTH - 1);
landRect.y := min(max(y, 0), LAND_HEIGHT - 1);
landRect.w := min(2*iceRadius, LAND_WIDTH - landRect.x - 1);
landRect.h := min(iceHeight, LAND_HEIGHT - landRect.y - 1);
UpdateLandTexture(landRect.x, landRect.w, landRect.y, landRect.h, true);        
end;



function FillLandCircleLinesBG(x, y, dx, dy: LongInt): Longword;
var i, t, by, bx: LongInt;
    cnt: Longword;
begin
cnt:= 0;
t:= y + dy;
if (t and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dx, 0) to Min(x + dx, LAND_WIDTH - 1) do
        if (Land[t, i] and lfIndestructible) = 0 then
            begin
            if (cReducedQuality and rqBlurryLand) = 0 then
                begin
                by:= t; bx:= i;
                end
            else
                begin
                by:= t div 2; bx:= i div 2;
                end;
            if ((Land[t, i] and lfBasic) <> 0) and (((LandPixels[by,bx] and AMask) shr AShift) = 255) and (not disableLandBack) then
                begin
                inc(cnt);
                LandPixels[by, bx]:= LandBackPixel(i, t)
                end
            else if ((Land[t, i] and lfObject) <> 0) or (((LandPixels[by,bx] and AMask) shr AShift) < 255) then
                LandPixels[by, bx]:= 0
            end;

t:= y - dy;
if (t and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dx, 0) to Min(x + dx, LAND_WIDTH - 1) do
        if (Land[t, i] and lfIndestructible) = 0 then
            begin
            if (cReducedQuality and rqBlurryLand) = 0 then
                begin
                by:= t; bx:= i;
                end
            else
                begin
                by:= t div 2; bx:= i div 2;
                end;
            if ((Land[t, i] and lfBasic) <> 0) and (((LandPixels[by,bx] and AMask) shr AShift) = 255) and (not disableLandBack) then
                begin
                inc(cnt);
                LandPixels[by, bx]:= LandBackPixel(i, t)
                end
            else if ((Land[t, i] and lfObject) <> 0) or (((LandPixels[by,bx] and AMask) shr AShift) < 255) then
                LandPixels[by, bx]:= 0
            end;

t:= y + dx;
if (t and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dy, 0) to Min(x + dy, LAND_WIDTH - 1) do
        if (Land[t, i] and lfIndestructible) = 0 then
            begin
            if (cReducedQuality and rqBlurryLand) = 0 then
                begin
                by:= t; bx:= i;
                end
            else
                begin
                by:= t div 2; bx:= i div 2;
                end;
            if ((Land[t, i] and lfBasic) <> 0) and (((LandPixels[by,bx] and AMask) shr AShift) = 255) and (not disableLandBack) then
                begin
                inc(cnt);
                LandPixels[by, bx]:= LandBackPixel(i, t)
                end
            else if ((Land[t, i] and lfObject) <> 0) or (((LandPixels[by,bx] and AMask) shr AShift) < 255) then
                LandPixels[by, bx]:= 0
            end;
t:= y - dx;
if (t and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dy, 0) to Min(x + dy, LAND_WIDTH - 1) do
        if (Land[t, i] and lfIndestructible) = 0 then
            begin
            if (cReducedQuality and rqBlurryLand) = 0 then
                begin
                by:= t; bx:= i;
                end
            else
                begin
                by:= t div 2; bx:= i div 2;
                end;
            if ((Land[t, i] and lfBasic) <> 0) and (((LandPixels[by,bx] and AMask) shr AShift) = 255) and (not disableLandBack) then
                begin
                inc(cnt);
                LandPixels[by, bx]:= LandBackPixel(i, t)
                end
            else if ((Land[t, i] and lfObject) <> 0) or (((LandPixels[by,bx] and AMask) shr AShift) < 255) then
                LandPixels[by, bx]:= 0
            end;
FillLandCircleLinesBG:= cnt;
end;

procedure FillLandCircleLinesEBC(x, y, dx, dy: LongInt);
var i, t: LongInt;
begin
t:= y + dy;
if (t and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dx, 0) to Min(x + dx, LAND_WIDTH - 1) do
        if ((Land[t, i] and lfBasic) <> 0) or ((Land[t, i] and lfObject) <> 0) then
            begin
            if (cReducedQuality and rqBlurryLand) = 0 then
                LandPixels[t, i]:= ExplosionBorderColor
            else
                LandPixels[t div 2, i div 2]:= ExplosionBorderColor;

            Land[t, i]:= (Land[t, i] or lfDamaged) and not lfIce;
            //Despeckle(i, t);
            LandDirty[t div 32, i div 32]:= 1;
            end;

t:= y - dy;
if (t and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dx, 0) to Min(x + dx, LAND_WIDTH - 1) do
        if ((Land[t, i] and lfBasic) <> 0) or ((Land[t, i] and lfObject) <> 0) then
            begin
            if (cReducedQuality and rqBlurryLand) = 0 then
                LandPixels[t, i]:= ExplosionBorderColor
            else
                LandPixels[t div 2, i div 2]:= ExplosionBorderColor;
            Land[t, i]:= (Land[t, i] or lfDamaged) and not lfIce;
            //Despeckle(i, t);
            LandDirty[t div 32, i div 32]:= 1;
            end;

t:= y + dx;
if (t and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dy, 0) to Min(x + dy, LAND_WIDTH - 1) do
        if ((Land[t, i] and lfBasic) <> 0) or ((Land[t, i] and lfObject) <> 0) then
            begin
            if (cReducedQuality and rqBlurryLand) = 0 then
                LandPixels[t, i]:= ExplosionBorderColor
            else
               LandPixels[t div 2, i div 2]:= ExplosionBorderColor;

            Land[t, i]:= (Land[t, i] or lfDamaged) and not lfIce;
            //Despeckle(i, t);
            LandDirty[t div 32, i div 32]:= 1;
            end;

t:= y - dx;
if (t and LAND_HEIGHT_MASK) = 0 then
    for i:= Max(x - dy, 0) to Min(x + dy, LAND_WIDTH - 1) do
        if ((Land[t, i] and lfBasic) <> 0) or ((Land[t, i] and lfObject) <> 0) then
            begin
            if (cReducedQuality and rqBlurryLand) = 0 then
                LandPixels[t, i]:= ExplosionBorderColor
            else
                LandPixels[t div 2, i div 2]:= ExplosionBorderColor;

            Land[t, i]:= (Land[t, i] or lfDamaged) and not lfIce;
            //Despeckle(i, y - dy);
            LandDirty[t div 32, i div 32]:= 1;
            end;
end;

function DrawExplosion(X, Y, Radius: LongInt): Longword;
var dx, dy, ty, tx, d: LongInt;
    cnt: Longword;
begin

// draw background land texture
    begin
    cnt:= 0;
    dx:= 0;
    dy:= Radius;
    d:= 3 - 2 * Radius;

    while (dx < dy) do
        begin
        inc(cnt, FillLandCircleLinesBG(x, y, dx, dy));
        if (d < 0) then
            d:= d + 4 * dx + 6
        else
            begin
            d:= d + 4 * (dx - dy) + 10;
            dec(dy)
            end;
        inc(dx)
        end;
    if (dx = dy) then
        inc(cnt, FillLandCircleLinesBG(x, y, dx, dy));
    end;

// draw a hole in land
if Radius > 20 then
    begin
    dx:= 0;
    dy:= Radius - 15;
    d:= 3 - 2 * dy;

    while (dx < dy) do
        begin
        FillLandCircleLines0(x, y, dx, dy);
        if (d < 0) then
            d:= d + 4 * dx + 6
        else
            begin
            d:= d + 4 * (dx - dy) + 10;
            dec(dy)
            end;
        inc(dx)
        end;
    if (dx = dy) then
        FillLandCircleLines0(x, y, dx, dy);
    end;

  // FillRoundInLand after erasing land pixels to allow Land 0 check for mask.png to function
    FillRoundInLand(X, Y, Radius, 0);

// draw explosion border
    begin
    inc(Radius, 4);
    dx:= 0;
    dy:= Radius;
    d:= 3 - 2 * Radius;
    while (dx < dy) do
        begin
        FillLandCircleLinesEBC(x, y, dx, dy);
        if (d < 0) then
            d:= d + 4 * dx + 6
        else
            begin
            d:= d + 4 * (dx - dy) + 10;
            dec(dy)
            end;
        inc(dx)
        end;
    if (dx = dy) then
        FillLandCircleLinesEBC(x, y, dx, dy);
    end;

tx:= Max(X - Radius - 1, 0);
dx:= Min(X + Radius + 1, LAND_WIDTH) - tx;
ty:= Max(Y - Radius - 1, 0);
dy:= Min(Y + Radius + 1, LAND_HEIGHT) - ty;
UpdateLandTexture(tx, dx, ty, dy, false);
DrawExplosion:= cnt
end;

procedure DrawHLinesExplosions(ar: PRangeArray; Radius: LongInt; y, dY: LongInt; Count: Byte);
var tx, ty, by, bx,  i: LongInt;
begin
for i:= 0 to Pred(Count) do
    begin
    for ty:= Max(y - Radius, 0) to Min(y + Radius, LAND_HEIGHT) do
        for tx:= Max(0, ar^[i].Left - Radius) to Min(LAND_WIDTH, ar^[i].Right + Radius) do
            begin
            if (Land[ty, tx] and lfIndestructible) = 0 then
                begin
                if (cReducedQuality and rqBlurryLand) = 0 then
                    begin
                    by:= ty; bx:= tx;
                    end
                else
                    begin
                    by:= ty div 2; bx:= tx div 2;
                    end;
                if ((Land[ty, tx] and lfBasic) <> 0) and (((LandPixels[by,bx] and AMask) shr AShift) = 255) and (not disableLandBack) then
                    LandPixels[by, bx]:= LandBackPixel(tx, ty)
                else if ((Land[ty, tx] and lfObject) <> 0) or (((LandPixels[by,bx] and AMask) shr AShift) < 255) then
                    LandPixels[by, bx]:= 0
                end
            end;
    inc(y, dY)
    end;

inc(Radius, 4);
dec(y, Count * dY);

for i:= 0 to Pred(Count) do
    begin
    for ty:= Max(y - Radius, 0) to Min(y + Radius, LAND_HEIGHT) do
        for tx:= Max(0, ar^[i].Left - Radius) to Min(LAND_WIDTH, ar^[i].Right + Radius) do
            if ((Land[ty, tx] and lfBasic) <> 0) or ((Land[ty, tx] and lfObject) <> 0) then
                begin
                 if (cReducedQuality and rqBlurryLand) = 0 then
                    LandPixels[ty, tx]:= ExplosionBorderColor
                else
                    LandPixels[ty div 2, tx div 2]:= ExplosionBorderColor;

                Land[ty, tx]:= (Land[ty, tx] or lfDamaged) and not lfIce;
                LandDirty[ty div 32, tx div 32]:= 1;
                end;
    inc(y, dY)
    end;


UpdateLandTexture(0, LAND_WIDTH, 0, LAND_HEIGHT, false)
end;

//
//  - (dX, dY) - direction, vector of length = 0.5
//
procedure DrawTunnel(X, Y, dX, dY: hwFloat; ticks, HalfWidth: LongInt);
var nx, ny, dX8, dY8: hwFloat;
    i, t, tx, ty, by, bx, stX, stY, ddy, ddx: Longint;
    despeckle : Boolean;
begin  // (-dY, dX) is (dX, dY) rotated by PI/2
stY:= hwRound(Y);
stX:= hwRound(X);

despeckle:= HalfWidth > 1;

nx:= X + dY * (HalfWidth + 8);
ny:= Y - dX * (HalfWidth + 8);

dX8:= dX * 8;
dY8:= dY * 8;
for i:= 0 to 7 do
    begin
    X:= nx - dX8;
    Y:= ny - dY8;
    for t:= -8 to ticks + 8 do
    begin
    X:= X + dX;
    Y:= Y + dY;
    tx:= hwRound(X);
    ty:= hwRound(Y);
    if ((ty and LAND_HEIGHT_MASK) = 0)
    and ((tx and LAND_WIDTH_MASK) = 0)
    and (((Land[ty, tx] and lfBasic) <> 0) or ((Land[ty, tx] and lfObject) <> 0)) then
        begin
        Land[ty, tx]:= Land[ty, tx] and not lfIce;
        if despeckle then
            begin
            Land[ty, tx]:= Land[ty, tx] or lfDamaged;
            LandDirty[ty div 32, tx div 32]:= 1
            end;
        if (cReducedQuality and rqBlurryLand) = 0 then
            LandPixels[ty, tx]:= ExplosionBorderColor
        else
            LandPixels[ty div 2, tx div 2]:= ExplosionBorderColor
        end
    end;
    nx:= nx - dY;
    ny:= ny + dX;
    end;

for i:= -HalfWidth to HalfWidth do
    begin
    X:= nx - dX8;
    Y:= ny - dY8;
    for t:= 0 to 7 do
        begin
        X:= X + dX;
        Y:= Y + dY;
        tx:= hwRound(X);
        ty:= hwRound(Y);
        if ((ty and LAND_HEIGHT_MASK) = 0) and ((tx and LAND_WIDTH_MASK) = 0) and (((Land[ty, tx] and lfBasic) <> 0)
        or ((Land[ty, tx] and lfObject) <> 0)) then
            begin
            Land[ty, tx]:= (Land[ty, tx] or lfDamaged) and not lfIce;
            if despeckle then
                LandDirty[ty div 32, tx div 32]:= 1;
            if (cReducedQuality and rqBlurryLand) = 0 then
                LandPixels[ty, tx]:= ExplosionBorderColor
            else
                LandPixels[ty div 2, tx div 2]:= ExplosionBorderColor
            end
        end;
    X:= nx;
    Y:= ny;
    for t:= 0 to ticks do
        begin
        X:= X + dX;
        Y:= Y + dY;
        tx:= hwRound(X);
        ty:= hwRound(Y);
        if ((ty and LAND_HEIGHT_MASK) = 0) and ((tx and LAND_WIDTH_MASK) = 0) and ((Land[ty, tx] and lfIndestructible) = 0) then
            begin
            if (cReducedQuality and rqBlurryLand) = 0 then
                begin
                by:= ty; bx:= tx;
                end
            else
                begin
                by:= ty div 2; bx:= tx div 2;
                end;
            if ((Land[ty, tx] and lfBasic) <> 0) and (((LandPixels[by,bx] and AMask) shr AShift) = 255) and (not disableLandBack) then
                LandPixels[by, bx]:= LandBackPixel(tx, ty)
            else if ((Land[ty, tx] and lfObject) <> 0) or (((LandPixels[by,bx] and AMask) shr AShift) < 255) then
                LandPixels[by, bx]:= 0;
            Land[ty, tx]:= 0;
            end
        end;
    for t:= 0 to 7 do
    begin
    X:= X + dX;
    Y:= Y + dY;
    tx:= hwRound(X);
    ty:= hwRound(Y);
    if ((ty and LAND_HEIGHT_MASK) = 0) and ((tx and LAND_WIDTH_MASK) = 0) and (((Land[ty, tx] and lfBasic) <> 0)
    or ((Land[ty, tx] and lfObject) <> 0)) then
        begin
        Land[ty, tx]:=( Land[ty, tx] or lfDamaged) and not lfIce;
        if despeckle then
            LandDirty[ty div 32, tx div 32]:= 1;
        if (cReducedQuality and rqBlurryLand) = 0 then
            LandPixels[ty, tx]:= ExplosionBorderColor
        else
            LandPixels[ty div 2, tx div 2]:= ExplosionBorderColor
        end
        end;
    nx:= nx - dY;
    ny:= ny + dX;
    end;

for i:= 0 to 7 do
    begin
    X:= nx - dX8;
    Y:= ny - dY8;
    for t:= -8 to ticks + 8 do
    begin
    X:= X + dX;
    Y:= Y + dY;
    tx:= hwRound(X);
    ty:= hwRound(Y);
    if ((ty and LAND_HEIGHT_MASK) = 0) and ((tx and LAND_WIDTH_MASK) = 0) and (((Land[ty, tx] and lfBasic) <> 0)
    or ((Land[ty, tx] and lfObject) <> 0)) then
        begin
        Land[ty, tx]:= (Land[ty, tx] or lfDamaged) and not lfIce;
        if despeckle then
            LandDirty[ty div 32, tx div 32]:= 1;
        if (cReducedQuality and rqBlurryLand) = 0 then
            LandPixels[ty, tx]:= ExplosionBorderColor
        else
            LandPixels[ty div 2, tx div 2]:= ExplosionBorderColor
        end
    end;
    nx:= nx - dY;
    ny:= ny + dX;
    end;

tx:= Max(stX - HalfWidth * 2 - 4 - abs(hwRound(dX * ticks)), 0);
ty:= Max(stY - HalfWidth * 2 - 4 - abs(hwRound(dY * ticks)), 0);
ddx:= Min(stX + HalfWidth * 2 + 4 + abs(hwRound(dX * ticks)), LAND_WIDTH) - tx;
ddy:= Min(stY + HalfWidth * 2 + 4 + abs(hwRound(dY * ticks)), LAND_HEIGHT) - ty;

UpdateLandTexture(tx, ddx, ty, ddy, false)
end;

function TryPlaceOnLand(cpX, cpY: LongInt; Obj: TSprite; Frame: LongInt; doPlace: boolean; indestructible: boolean): boolean;
var X, Y, bpp, h, w, row, col, gx, gy, numFramesFirstCol: LongInt;
    p: PByteArray;
    Image: PSDL_Surface;
begin
TryPlaceOnLand:= false;
numFramesFirstCol:= SpritesData[Obj].imageHeight div SpritesData[Obj].Height;

TryDo(SpritesData[Obj].Surface <> nil, 'Assert SpritesData[Obj].Surface failed', true);
Image:= SpritesData[Obj].Surface;
w:= SpritesData[Obj].Width;
h:= SpritesData[Obj].Height;
row:= Frame mod numFramesFirstCol;
col:= Frame div numFramesFirstCol;

if SDL_MustLock(Image) then
    SDLTry(SDL_LockSurface(Image) >= 0, true);

bpp:= Image^.format^.BytesPerPixel;
TryDo(bpp = 4, 'It should be 32 bpp sprite', true);
// Check that sprite fits free space
p:= @(PByteArray(Image^.pixels)^[ Image^.pitch * row * h + col * w * 4 ]);
case bpp of
    4: for y:= 0 to Pred(h) do
        begin
        for x:= 0 to Pred(w) do
            if (PLongword(@(p^[x * 4]))^) <> 0 then
                if ((cpY + y) <= Longint(topY)) or ((cpY + y) >= LAND_HEIGHT) or
                   ((cpX + x) <= Longint(leftX)) or ((cpX + x) >= Longint(rightX)) or (Land[cpY + y, cpX + x] <> 0) then
                    begin
                        if SDL_MustLock(Image) then
                            SDL_UnlockSurface(Image);
                        exit;
                    end;
        p:= @(p^[Image^.pitch]);
        end;
    end;

TryPlaceOnLand:= true;
if not doPlace then
    begin
    if SDL_MustLock(Image) then
        SDL_UnlockSurface(Image);
    exit
    end;

// Checked, now place
p:= @(PByteArray(Image^.pixels)^[ Image^.pitch * row * h + col * w * 4 ]);
case bpp of
    4: for y:= 0 to Pred(h) do
        begin
        for x:= 0 to Pred(w) do
            if (PLongword(@(p^[x * 4]))^) <> 0 then
                   begin
                if (cReducedQuality and rqBlurryLand) = 0 then
                    begin
                    gX:= cpX + x;
                    gY:= cpY + y;
                    end
                else
                     begin
                     gX:= (cpX + x) div 2;
                     gY:= (cpY + y) div 2;
                    end;
                if indestructible then
                    Land[cpY + y, cpX + x]:= lfIndestructible
                else if (LandPixels[gY, gX] and AMask) shr AShift = 255 then  // This test assumes lfBasic and lfObject differ only graphically
                    Land[cpY + y, cpX + x]:= lfBasic
                else
                    Land[cpY + y, cpX + x]:= lfObject;
                // For testing only. Intent is to flag this on objects with masks, or use it for an ice ray gun
                if (Theme = 'Snow') or (Theme = 'Christmas') then
                    Land[cpY + y, cpX + x]:= Land[cpY + y, cpX + x] or lfIce;
                    LandPixels[gY, gX]:= PLongword(@(p^[x * 4]))^
                end;
        p:= @(p^[Image^.pitch]);
        end;
    end;
if SDL_MustLock(Image) then
    SDL_UnlockSurface(Image);

x:= Max(cpX, leftX);
w:= Min(cpX + Image^.w, LAND_WIDTH) - x;
y:= Max(cpY, topY);
h:= Min(cpY + Image^.h, LAND_HEIGHT) - y;
UpdateLandTexture(x, w, y, h, true)
end;

function Despeckle(X, Y: LongInt): boolean;
var nx, ny, i, j, c, xx, yy: LongInt;
    pixelsweep: boolean;
begin
    Despeckle:= true;

    if (cReducedQuality and rqBlurryLand) = 0 then
    begin
        xx:= X;
        yy:= Y;
    end
    else
    begin
        xx:= X div 2;
        yy:= Y div 2;
    end;

    pixelsweep:= ((Land[Y, X] and $FF00) = 0) and (LandPixels[yy, xx] <> 0);
    if (((Land[Y, X] and lfDamaged) <> 0) and ((Land[Y, X] and lfIndestructible) = 0)) or pixelsweep then
    begin
        c:= 0;
        for i:= -1 to 1 do
            for j:= -1 to 1 do
                if (i <> 0) or (j <> 0) then
                begin
                    ny:= Y + i;
                    nx:= X + j;
                    if ((ny and LAND_HEIGHT_MASK) = 0) and ((nx and LAND_WIDTH_MASK) = 0) then
                    begin
                        if pixelsweep then
                        begin
                            if ((cReducedQuality and rqBlurryLand) <> 0) then
                            begin
                                nx:= nx div 2;
                                ny:= ny div 2
                            end;
                            if LandPixels[ny, nx] <> 0 then
                                inc(c);
                        end
                    else if Land[ny, nx] > 255 then
                        inc(c);
                    end
                end;

        if c < 4 then // 0-3 neighbours
        begin
            if ((Land[Y, X] and lfBasic) <> 0) and (not disableLandBack) then
                LandPixels[yy, xx]:= LandBackPixel(X, Y)
            else
                LandPixels[yy, xx]:= 0;

            if not pixelsweep then
            begin
                Land[Y, X]:= 0;
                exit
            end
        end;
    end;
    Despeckle:= false
end;

procedure Smooth(X, Y: LongInt);
begin
// a bit of AA for explosions
if (Land[Y, X] = 0) and (Y > LongInt(topY) + 1) and
    (Y < LAND_HEIGHT-2) and (X > LongInt(leftX) + 1) and (X < LongInt(rightX) - 1) then
    begin
    if ((((Land[y, x-1] and lfDamaged) <> 0) and (((Land[y+1,x] and lfDamaged) <> 0)) or ((Land[y-1,x] and lfDamaged) <> 0))
    or (((Land[y, x+1] and lfDamaged) <> 0) and (((Land[y-1,x] and lfDamaged) <> 0) or ((Land[y+1,x] and lfDamaged) <> 0)))) then
        begin
        if (cReducedQuality and rqBlurryLand) = 0 then
            begin
            if ((LandPixels[y,x] and AMask) shr AShift) < 10 then
                LandPixels[y,x]:= (ExplosionBorderColor and (not AMask)) or (128 shl AShift)
            else
                LandPixels[y,x]:=
                                (((((LandPixels[y,x] and RMask shr RShift) div 2)+((ExplosionBorderColor and RMask) shr RShift) div 2) and $FF) shl RShift) or
                                (((((LandPixels[y,x] and GMask shr GShift) div 2)+((ExplosionBorderColor and GMask) shr GShift) div 2) and $FF) shl GShift) or
                                (((((LandPixels[y,x] and BMask shr BShift) div 2)+((ExplosionBorderColor and BMask) shr BShift) div 2) and $FF) shl BShift) or ($FF shl AShift)
            end;
        if (Land[y, x-1] = lfObject) then
            Land[y,x]:= lfObject
        else if (Land[y, x+1] = lfObject) then
            Land[y,x]:= lfObject
        else
            Land[y,x]:= lfBasic;
        end
    else if ((((Land[y, x-1] and lfDamaged) <> 0) and ((Land[y+1,x-1] and lfDamaged) <> 0) and ((Land[y+2,x] and lfDamaged) <> 0))
    or (((Land[y, x-1] and lfDamaged) <> 0) and ((Land[y-1,x-1] and lfDamaged) <> 0) and ((Land[y-2,x] and lfDamaged) <> 0))
    or (((Land[y, x+1] and lfDamaged) <> 0) and ((Land[y+1,x+1] and lfDamaged) <> 0) and ((Land[y+2,x] and lfDamaged) <> 0))
    or (((Land[y, x+1] and lfDamaged) <> 0) and ((Land[y-1,x+1] and lfDamaged) <> 0) and ((Land[y-2,x] and lfDamaged) <> 0))
    or (((Land[y+1, x] and lfDamaged) <> 0) and ((Land[y+1,x+1] and lfDamaged) <> 0) and ((Land[y,x+2] and lfDamaged) <> 0))
    or (((Land[y-1, x] and lfDamaged) <> 0) and ((Land[y-1,x+1] and lfDamaged) <> 0) and ((Land[y,x+2] and lfDamaged) <> 0))
    or (((Land[y+1, x] and lfDamaged) <> 0) and ((Land[y+1,x-1] and lfDamaged) <> 0) and ((Land[y,x-2] and lfDamaged) <> 0))
    or (((Land[y-1, x] and lfDamaged) <> 0) and ((Land[y-1,x-1] and lfDamaged) <> 0) and ((Land[y,x-2] and lfDamaged) <> 0))) then
        begin
        if (cReducedQuality and rqBlurryLand) = 0 then
            begin
            if ((LandPixels[y,x] and AMask) shr AShift) < 10 then
                LandPixels[y,x]:= (ExplosionBorderColor and (not AMask)) or (64 shl AShift)
            else
                LandPixels[y,x]:=
                                (((((LandPixels[y,x] and RMask shr RShift) * 3 div 4)+((ExplosionBorderColor and RMask) shr RShift) div 4) and $FF) shl RShift) or
                                (((((LandPixels[y,x] and GMask shr GShift) * 3 div 4)+((ExplosionBorderColor and GMask) shr GShift) div 4) and $FF) shl GShift) or
                                (((((LandPixels[y,x] and BMask shr BShift) * 3 div 4)+((ExplosionBorderColor and BMask) shr BShift) div 4) and $FF) shl BShift) or ($FF shl AShift)
            end;
        if (Land[y, x-1] = lfObject) then
            Land[y, x]:= lfObject
        else if (Land[y, x+1] = lfObject) then
            Land[y, x]:= lfObject
        else if (Land[y+1, x] = lfObject) then
            Land[y, x]:= lfObject
        else if (Land[y-1, x] = lfObject) then
        Land[y, x]:= lfObject
        else Land[y,x]:= lfBasic
        end
    end
else if ((cReducedQuality and rqBlurryLand) = 0) and (LandPixels[Y, X] and AMask = 255)
and (Land[Y, X] and (lfDamaged or lfBasic) = lfBasic)
and (Y > LongInt(topY) + 1) and (Y < LAND_HEIGHT-2) and (X > LongInt(leftX) + 1) and (X < LongInt(rightX) - 1) then
    begin
    if ((((Land[y, x-1] and lfDamaged) <> 0) and (((Land[y+1,x] and lfDamaged) <> 0)) or ((Land[y-1,x] and lfDamaged) <> 0))
    or (((Land[y, x+1] and lfDamaged) <> 0) and (((Land[y-1,x] and lfDamaged) <> 0) or ((Land[y+1,x] and lfDamaged) <> 0)))) then
        begin
        LandPixels[y,x]:=
                        (((((LandPixels[y,x] and RMask shr RShift) div 2)+((ExplosionBorderColor and RMask) shr RShift) div 2) and $FF) shl RShift) or
                        (((((LandPixels[y,x] and GMask shr GShift) div 2)+((ExplosionBorderColor and GMask) shr GShift) div 2) and $FF) shl GShift) or
                        (((((LandPixels[y,x] and BMask shr BShift) div 2)+((ExplosionBorderColor and BMask) shr BShift) div 2) and $FF) shl BShift) or ($FF shl AShift)
        end
    else if ((((Land[y, x-1] and lfDamaged) <> 0) and ((Land[y+1,x-1] and lfDamaged) <> 0) and ((Land[y+2,x] and lfDamaged) <> 0))
    or (((Land[y, x-1] and lfDamaged) <> 0) and ((Land[y-1,x-1] and lfDamaged) <> 0) and ((Land[y-2,x] and lfDamaged) <> 0))
    or (((Land[y, x+1] and lfDamaged) <> 0) and ((Land[y+1,x+1] and lfDamaged) <> 0) and ((Land[y+2,x] and lfDamaged) <> 0))
    or (((Land[y, x+1] and lfDamaged) <> 0) and ((Land[y-1,x+1] and lfDamaged) <> 0) and ((Land[y-2,x] and lfDamaged) <> 0))
    or (((Land[y+1, x] and lfDamaged) <> 0) and ((Land[y+1,x+1] and lfDamaged) <> 0) and ((Land[y,x+2] and lfDamaged) <> 0))
    or (((Land[y-1, x] and lfDamaged) <> 0) and ((Land[y-1,x+1] and lfDamaged) <> 0) and ((Land[y,x+2] and lfDamaged) <> 0))
    or (((Land[y+1, x] and lfDamaged) <> 0) and ((Land[y+1,x-1] and lfDamaged) <> 0) and ((Land[y,x-2] and lfDamaged) <> 0))
    or (((Land[y-1, x] and lfDamaged) <> 0) and ((Land[y-1,x-1] and lfDamaged) <> 0) and ((Land[y,x-2] and lfDamaged) <> 0))) then
        begin
        LandPixels[y,x]:=
                        (((((LandPixels[y,x] and RMask shr RShift) * 3 div 4)+((ExplosionBorderColor and RMask) shr RShift) div 4) and $FF) shl RShift) or
                        (((((LandPixels[y,x] and GMask shr GShift) * 3 div 4)+((ExplosionBorderColor and GMask) shr GShift) div 4) and $FF) shl GShift) or
                        (((((LandPixels[y,x] and BMask shr BShift) * 3 div 4)+((ExplosionBorderColor and BMask) shr BShift) div 4) and $FF) shl BShift) or ($FF shl AShift)
        end
    end
end;

function SweepDirty: boolean;
var x, y, xx, yy, ty, tx: LongInt;
    bRes, updateBlock, resweep, recheck: boolean;
begin
bRes:= false;
reCheck:= true;

while recheck do
    begin
    recheck:= false;
    for y:= 0 to LAND_HEIGHT div 32 - 1 do
        begin
        for x:= 0 to LAND_WIDTH div 32 - 1 do
            begin
            if LandDirty[y, x] = 1 then
                begin
                updateBlock:= false;
                resweep:= true;
                ty:= y * 32;
                tx:= x * 32;
                while(resweep) do
                    begin
                    resweep:= false;
                    for yy:= ty to ty + 31 do
                        for xx:= tx to tx + 31 do
                            if Despeckle(xx, yy) then
                                begin
                                bRes:= true;
                                updateBlock:= true;
                                resweep:= true;
                                if (yy = ty) and (y > 0) then
                                    begin
                                    LandDirty[y-1, x]:= 1;
                                    recheck:= true;
                                    end
                                else if (yy = ty+31) and (y < LAND_HEIGHT div 32 - 1) then
                                    begin
                                    LandDirty[y+1, x]:= 1;
                                    recheck:= true;
                                    end;
                                if (xx = tx) and (x > 0) then
                                    begin
                                    LandDirty[y, x-1]:= 1;
                                    recheck:= true;
                                    end
                                else if (xx = tx+31) and (x < LAND_WIDTH div 32 - 1) then
                                    begin
                                    LandDirty[y, x+1]:= 1;
                                    recheck:= true;
                                    end
                                end;
                    end;
                if updateBlock then
                    UpdateLandTexture(tx, 32, ty, 32, false);
                LandDirty[y, x]:= 2;
                end;
            end;
        end;
     end;

for y:= 0 to LAND_HEIGHT div 32 - 1 do
    for x:= 0 to LAND_WIDTH div 32 - 1 do
        if LandDirty[y, x] <> 0 then
            begin
            LandDirty[y, x]:= 0;
            ty:= y * 32;
            tx:= x * 32;
            for yy:= ty to ty + 31 do
                for xx:= tx to tx + 31 do
                    Smooth(xx,yy)
            end;

SweepDirty:= bRes;
end;


// Return true if outside of land or not the value tested, used right now for some X/Y movement that does not use normal hedgehog movement in GSHandlers.inc
function CheckLandValue(X, Y: LongInt; LandFlag: Word): boolean; inline;
begin
    CheckLandValue:= ((X and LAND_WIDTH_MASK <> 0) or (Y and LAND_HEIGHT_MASK <> 0)) or ((Land[Y, X] and LandFlag) = 0)
end;

function LandBackPixel(x, y: LongInt): LongWord; inline;
var p: PLongWordArray;
begin
    if LandBackSurface = nil then
        LandBackPixel:= 0
    else
        begin
        p:= LandBackSurface^.pixels;
        LandBackPixel:= p^[LandBackSurface^.w * (y mod LandBackSurface^.h) + (x mod LandBackSurface^.w)];// or $FF000000;
        end
end;


procedure DrawLine(X1, Y1, X2, Y2: LongInt; Color: Longword);
var
  eX, eY, dX, dY: LongInt;
  i, sX, sY, x, y, d: LongInt;
begin
eX:= 0;
eY:= 0;
dX:= X2 - X1;
dY:= Y2 - Y1;

if (dX > 0) then
    sX:= 1
else
    if (dX < 0) then
        begin
        sX:= -1;
        dX:= -dX
        end
    else
        sX:= dX;

if (dY > 0) then
    sY:= 1
else
    if (dY < 0) then
        begin
        sY:= -1;
        dY:= -dY
        end
    else
        sY:= dY;

if (dX > dY) then
    d:= dX
else
    d:= dY;

x:= X1;
y:= Y1;

for i:= 0 to d do
    begin
    inc(eX, dX);
    inc(eY, dY);
    if (eX > d) then
        begin
        dec(eX, d);
        inc(x, sX);
        end;
    if (eY > d) then
        begin
        dec(eY, d);
        inc(y, sY);
        end;

    if ((x and LAND_WIDTH_MASK) = 0) and ((y and LAND_HEIGHT_MASK) = 0) then
        Land[y, x]:= Color;
    end
end;

procedure DrawDots(x, y, xx, yy: Longint; Color: Longword); inline;
begin
    if (((x + xx) and LAND_WIDTH_MASK) = 0) and (((y + yy) and LAND_HEIGHT_MASK) = 0) then Land[y + yy, x + xx]:= Color;
    if (((x + xx) and LAND_WIDTH_MASK) = 0) and (((y - yy) and LAND_HEIGHT_MASK) = 0) then Land[y - yy, x + xx]:= Color;
    if (((x - xx) and LAND_WIDTH_MASK) = 0) and (((y + yy) and LAND_HEIGHT_MASK) = 0) then Land[y + yy, x - xx]:= Color;
    if (((x - xx) and LAND_WIDTH_MASK) = 0) and (((y - yy) and LAND_HEIGHT_MASK) = 0) then Land[y - yy, x - xx]:= Color;
    if (((x + yy) and LAND_WIDTH_MASK) = 0) and (((y + xx) and LAND_HEIGHT_MASK) = 0) then Land[y + xx, x + yy]:= Color;
    if (((x + yy) and LAND_WIDTH_MASK) = 0) and (((y - xx) and LAND_HEIGHT_MASK) = 0) then Land[y - xx, x + yy]:= Color;
    if (((x - yy) and LAND_WIDTH_MASK) = 0) and (((y + xx) and LAND_HEIGHT_MASK) = 0) then Land[y + xx, x - yy]:= Color;
    if (((x - yy) and LAND_WIDTH_MASK) = 0) and (((y - xx) and LAND_HEIGHT_MASK) = 0) then Land[y - xx, x - yy]:= Color;
end;

procedure DrawLines(X1, Y1, X2, Y2, XX, YY: LongInt; color: Longword);
var
  eX, eY, dX, dY: LongInt;
  i, sX, sY, x, y, d: LongInt;
  f: boolean;
begin
    eX:= 0;
    eY:= 0;
    dX:= X2 - X1;
    dY:= Y2 - Y1;

    if (dX > 0) then
        sX:= 1
    else
        if (dX < 0) then
            begin
            sX:= -1;
            dX:= -dX
            end
        else
            sX:= dX;

    if (dY > 0) then
        sY:= 1
    else
        if (dY < 0) then
            begin
            sY:= -1;
            dY:= -dY
            end
        else
            sY:= dY;

    if (dX > dY) then
        d:= dX
    else
        d:= dY;

    x:= X1;
    y:= Y1;

    for i:= 0 to d do
        begin
        inc(eX, dX);
        inc(eY, dY);

        f:= eX > d;
        if f then
            begin
            dec(eX, d);
            inc(x, sX);
            DrawDots(x, y, xx, yy, color)
            end;
        if (eY > d) then
            begin
            dec(eY, d);
            inc(y, sY);
            f:= true;
            DrawDots(x, y, xx, yy, color)
            end;

        if not f then
            DrawDots(x, y, xx, yy, color)
        end
end;

procedure DrawThickLine(X1, Y1, X2, Y2, radius: LongInt; color: Longword);
var dx, dy, d: LongInt;
begin
    dx:= 0;
    dy:= Radius;
    d:= 3 - 2 * Radius;
    while (dx < dy) do
        begin
        DrawLines(x1, y1, x2, y2, dx, dy, color);
        if (d < 0) then
            d:= d + 4 * dx + 6
        else
            begin
            d:= d + 4 * (dx - dy) + 10;
            dec(dy)
            end;
        inc(dx)
        end;
    if (dx = dy) then
        DrawLines(x1, y1, x2, y2, dx, dy, color);
end;


procedure DumpLandToLog(x, y, r: LongInt);
var xx, yy, dx: LongInt;
    s: shortstring;
begin
    s[0]:= char(r * 2 + 1);
    for yy:= y - r to y + r do
        begin
        for dx:= 0 to r*2 do
            begin
            xx:= dx - r + x;
            if (xx = x) and (yy = y) then
                s[dx + 1]:= 'X'
            else if Land[yy, xx] > 255 then
                s[dx + 1]:= 'O'
            else if Land[yy, xx] > 0 then
                s[dx + 1]:= '*'
            else
                s[dx + 1]:= '.'
            end;
        AddFileLog('Land dump: ' + s);
        end;
end;

end.