/*
 * Copyright (C) 2002, 2006 by the Widelands Development Team
 *
 * 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; either version 2
 * of the License, or (at your option) any later version.
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include "field.h"
#include "mapviewpixelfunctions.h"

/**
 * Set the field's brightness based upon the slopes.
 * Slopes are calulated as this field's height - neighbour's height.
 */
void Field::set_brightness(int l, int r, int tl, int tr, int bl, int br)
{
	static float flatbrightness = 0; // HACK to normalize flat terrain to zero brightness
	if (!flatbrightness)
		flatbrightness = MapviewPixelFunctions::calc_brightness(0, 0, 0, 0, 0, 0);

	float b =
		MapviewPixelFunctions::calc_brightness(l, r, tl, tr, bl, br) - flatbrightness;

	if (b > 0)
		b *= 1.5;

	if (b < -128) b = -128;
	else if (b > 127) b = 127;
	brightness = (char)b;
}
