(*
 * Hedgewars, a free turn based strategy game
 * Copyright (c) 2009 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
 *)

unit uLandTexture;
interface
uses SDLh;

procedure UpdateLandTexture(X, Width, Y, Height: LongInt);
procedure DrawLand(dX, dY: LongInt);
procedure FreeLand;

implementation
uses uMisc, uLand, uStore, GL, uConsts;

const TEXSIZE = 256;
	LANDTEXARW = LAND_WIDTH div TEXSIZE;
	LANDTEXARH = LAND_HEIGHT div TEXSIZE;

var
	LandTextures: array[0..LANDTEXARW - 1, 0..LANDTEXARH - 1] of
			record
			shouldUpdate: boolean;
			tex: PTexture;
			end;

	tmpPixels: array [0..TEXSIZE - 1, 0..TEXSIZE - 1] of LongWord;

function Pixels(x, y: Longword): Pointer;
var ty: Longword;
begin
for ty:= 0 to TEXSIZE - 1 do
	Move(LandPixels[y * TEXSIZE + ty, x * TEXSIZE], tmpPixels[ty, 0], sizeof(Longword) * TEXSIZE);
	
Pixels:= @tmpPixels
end;

procedure UpdateLandTexture(X, Width, Y, Height: LongInt);
var tx, ty: Longword;
begin
TryDo((X >= 0) and (X < LAND_WIDTH), 'UpdateLandTexture: wrong X parameter', true);
TryDo(X + Width <= LAND_WIDTH, 'UpdateLandTexture: wrong Width parameter', true);
TryDo((Y >= 0) and (Y < LAND_HEIGHT), 'UpdateLandTexture: wrong Y parameter', true);
TryDo(Y + Height <= LAND_HEIGHT, 'UpdateLandTexture: wrong Height parameter', true);

for ty:= Y div TEXSIZE to (Y + Height - 1) div TEXSIZE do
	for tx:= X div TEXSIZE to (X + Width - 1) div TEXSIZE do
		LandTextures[tx, ty].shouldUpdate:= true
end;

procedure RealLandTexUpdate;
var x, y: LongWord;
begin
if LandTextures[0, 0].tex = nil then
	for x:= 0 to LANDTEXARW -1 do
		for y:= 0 to LANDTEXARH - 1 do
			with LandTextures[x, y] do
				tex:= NewTexture(TEXSIZE, TEXSIZE, Pixels(x, y))
else
	for x:= 0 to LANDTEXARW -1 do
		for y:= 0 to LANDTEXARH - 1 do
			with LandTextures[x, y] do
				if shouldUpdate then
					begin
					shouldUpdate:= false;
					glBindTexture(GL_TEXTURE_2D, tex^.id);
					glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, TEXSIZE, TEXSIZE, GL_RGBA, GL_UNSIGNED_BYTE, Pixels(x, y));
					end
end;

procedure DrawLand(dX, dY: LongInt);
var x, y: LongInt;
begin
RealLandTexUpdate;

for x:= 0 to LANDTEXARW -1 do
	for y:= 0 to LANDTEXARH - 1 do
		with LandTextures[x, y] do
			DrawTexture(dX + x * TEXSIZE, dY + y * TEXSIZE, tex)
end;

procedure FreeLand;
var x, y: LongInt;
begin
for x:= 0 to LANDTEXARW -1 do
	for y:= 0 to LANDTEXARH - 1 do
		with LandTextures[x, y] do
			FreeTexture(tex)
end;

end.