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engines/ultima/nuvie/misc/u6_line_walker.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "ultima/nuvie/misc/u6_line_walker.h"
+
+namespace Ultima {
+namespace Nuvie {
+
+U6LineWalker::U6LineWalker(uint32 sx, uint32 sy, uint32 ex, uint32 ey)
+	: start_x(sx), start_y(sy), end_x(ex), end_y(ey), cur_x(sx), cur_y(sy), cur_step(0) {
+	sint32 delta_x = end_x - start_x;
+	sint32 delta_y = end_y - start_y;
+
+	yoffset[0] = 0;
+	if (delta_x >= 0) {
+		xoffset[0] = 1;
+		xoffset[1] = 1;
+	} else {
+		delta_x = -delta_x;
+		xoffset[0] = -1;
+		xoffset[1] = -1;
+	}
+
+	if (delta_y >= 0) {
+		yoffset[1] = 1;
+	} else {
+		delta_y = -delta_y;
+		yoffset[1] = -1;
+	}
+
+	if (delta_x < delta_y) {
+		sint32 tmp_var = delta_x;
+		delta_x = delta_y;
+		delta_y = tmp_var;
+		yoffset[0] = yoffset[1];
+		xoffset[1] = xoffset[0];
+		xoffset[0] = 0;
+	}
+
+	max_length = delta_x;
+
+	line_counter = delta_y + delta_y - delta_x;
+	line_inc[0] = delta_y + delta_y;
+	line_inc[1] = (delta_y - delta_x) * 2;
+}
+
+U6LineWalker::~U6LineWalker() {
+	// TODO Auto-generated destructor stub
+}
+
+
+bool U6LineWalker::step() {
+	if (cur_step >= max_length)
+		return false;
+
+	uint8 idx = line_counter < 0 ? 0 : 1;
+
+	line_counter += line_inc[idx];
+	cur_x +=  xoffset[idx];
+	cur_y +=  yoffset[idx];
+
+	cur_step++;
+
+	return true;
+}
+
+bool U6LineWalker::next(uint32 *x, uint32 *y) {
+	bool ret = step();
+
+	*x = cur_x;
+	*y = cur_y;
+
+	return ret;
+}
+
+} // End of namespace Nuvie
+} // End of namespace Ultima