1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
|
/* 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 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
*/
#include "common/stream.h"
#include "draci/walking.h"
#include "draci/screen.h"
#include "draci/sprite.h"
namespace Draci {
void WalkingMap::load(const byte *data, uint length) {
Common::MemoryReadStream mapReader(data, length);
_realWidth = mapReader.readUint16LE();
_realHeight = mapReader.readUint16LE();
_deltaX = mapReader.readUint16LE();
_deltaY = mapReader.readUint16LE();
_mapWidth = mapReader.readUint16LE();
_mapHeight = mapReader.readUint16LE();
_byteWidth = mapReader.readUint16LE();
// Set the data pointer to raw map data
_data = data + mapReader.pos();
}
bool WalkingMap::isWalkable(int x, int y) const {
// Convert to map pixels
x = x / _deltaX;
y = y / _deltaY;
int pixelIndex = _mapWidth * y + x;
int byteIndex = pixelIndex / 8;
int mapByte = _data[byteIndex];
return mapByte & (1 << pixelIndex % 8);
}
Sprite *WalkingMap::constructDrawableOverlay() {
// HACK: Create a visible overlay from the walking map so we can test it
byte *wlk = new byte[kScreenWidth * kScreenHeight];
memset(wlk, 255, kScreenWidth * kScreenHeight);
for (uint i = 0; i < kScreenWidth; ++i) {
for (uint j = 0; j < kScreenHeight; ++j) {
if (isWalkable(i, j)) {
wlk[j * kScreenWidth + i] = 2;
}
}
}
Sprite *ov = new Sprite(wlk, kScreenWidth, kScreenHeight, 0, 0, false);
delete[] wlk;
return ov;
}
/**
* @brief For a given point, find a nearest walkable point on the walking map
*
* @param startX x coordinate of the point
* @param startY y coordinate of the point
*
* @return A Common::Point representing the nearest walkable point
*
* The algorithm was copied from the original engine for exactness.
* TODO: Study this algorithm in more detail so it can be documented properly and
* possibly improved / simplified.
*/
Common::Point WalkingMap::findNearestWalkable(int startX, int startY, Common::Rect searchRect) const {
// If the starting point is walkable, just return that
if (searchRect.contains(startX, startY) && isWalkable(startX, startY)) {
return Common::Point(startX, startY);
}
int signs[] = { 1, -1 };
const uint kSignsNum = 2;
int radius = 0;
int x, y;
int dx, dy;
int prediction;
// The place where, eventually, the result coordinates will be stored
int finalX, finalY;
// The algorithm appears to start off with an ellipse with the minor radius equal to
// zero and the major radius equal to the walking map delta (the number of pixels
// one map pixel represents). It then uses a heuristic to gradually reshape it into
// a circle (by shortening the major radius and lengthening the minor one). At each
// such resizing step, it checks some select points on the ellipse for walkability.
// It also does the same check for the ellipse perpendicular to it (rotated by 90 degrees).
while (1) {
// The default major radius
radius += _deltaX;
// The ellipse radii (minor, major) that get resized
x = 0;
y = radius;
// Heuristic variables
prediction = 1 - radius;
dx = 3;
dy = 2 * radius - 2;
do {
// The following two loops serve the purpose of checking the points on the two
// ellipses for walkability. The signs[] array is there to obliterate the need
// of writing out all combinations manually.
for (uint i = 0; i < kSignsNum; ++i) {
finalY = startY + y * signs[i];
for (uint j = 0; j < kSignsNum; ++j) {
finalX = startX + x * signs[j];
// If the current point is walkable, return it
if (searchRect.contains(finalX, finalY) && isWalkable(finalX, finalY)) {
return Common::Point(finalX, finalY);
}
}
}
if (x == y) {
// If the starting point is walkable, just return that
if (searchRect.contains(finalX, finalY) && isWalkable(finalX, finalY)) {
return Common::Point(finalX, finalY);
}
}
for (uint i = 0; i < kSignsNum; ++i) {
finalY = startY + x * signs[i];
for (uint j = 0; j < kSignsNum; ++j) {
finalX = startX + y * signs[j];
// If the current point is walkable, return it
if (searchRect.contains(finalX, finalY) && isWalkable(finalX, finalY)) {
return Common::Point(finalX, finalY);
}
}
}
// If prediction is non-negative, we need to decrease the major radius of the
// ellipse
if (prediction >= 0) {
prediction -= dy;
dy -= 2 * _deltaX;
y -= _deltaX;
}
// Increase the minor radius of the ellipse and update heuristic variables
prediction += dx;
dx += 2 * _deltaX;
x += _deltaX;
// If the current ellipse has been reshaped into a circle,
// end this loop and enlarge the radius
} while (x <= y);
}
}
}
|
