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
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
|
/*
Minetest-c55
Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser 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.
*/
#include "collision.h"
#include "mapblock.h"
#include "map.h"
#include "nodedef.h"
#include "gamedef.h"
collisionMoveResult collisionMoveSimple(Map *map, IGameDef *gamedef,
f32 pos_max_d, const core::aabbox3d<f32> &box_0,
f32 dtime, v3f &pos_f, v3f &speed_f)
{
collisionMoveResult result;
// If there is no speed, there are no collisions
if(speed_f.getLength() == 0)
return result;
v3f oldpos_f = pos_f;
v3s16 oldpos_i = floatToInt(oldpos_f, BS);
/*
Calculate new position
*/
pos_f += speed_f * dtime;
/*
Collision detection
*/
// position in nodes
v3s16 pos_i = floatToInt(pos_f, BS);
/*
Collision uncertainty radius
Make it a bit larger than the maximum distance of movement
*/
f32 d = pos_max_d * 1.1;
// A fairly large value in here makes moving smoother
//f32 d = 0.15*BS;
// This should always apply, otherwise there are glitches
assert(d > pos_max_d);
/*
Calculate collision box
*/
core::aabbox3d<f32> box = box_0;
box.MaxEdge += pos_f;
box.MinEdge += pos_f;
core::aabbox3d<f32> oldbox = box_0;
oldbox.MaxEdge += oldpos_f;
oldbox.MinEdge += oldpos_f;
/*
If the object lies on a walkable node, this is set to true.
*/
result.touching_ground = false;
/*
Go through every node around the object
*/
s16 min_x = (box_0.MinEdge.X / BS) - 2;
s16 min_y = (box_0.MinEdge.Y / BS) - 2;
s16 min_z = (box_0.MinEdge.Z / BS) - 2;
s16 max_x = (box_0.MaxEdge.X / BS) + 1;
s16 max_y = (box_0.MaxEdge.Y / BS) + 1;
s16 max_z = (box_0.MaxEdge.Z / BS) + 1;
for(s16 y = oldpos_i.Y + min_y; y <= oldpos_i.Y + max_y; y++)
for(s16 z = oldpos_i.Z + min_z; z <= oldpos_i.Z + max_z; z++)
for(s16 x = oldpos_i.X + min_x; x <= oldpos_i.X + max_x; x++)
{
try{
// Object collides into walkable nodes
MapNode n = map->getNode(v3s16(x,y,z));
if(gamedef->getNodeDefManager()->get(n).walkable == false)
continue;
}
catch(InvalidPositionException &e)
{
// Doing nothing here will block the object from
// walking over map borders
}
core::aabbox3d<f32> nodebox = getNodeBox(v3s16(x,y,z), BS);
/*
See if the object is touching ground.
Object touches ground if object's minimum Y is near node's
maximum Y and object's X-Z-area overlaps with the node's
X-Z-area.
Use 0.15*BS so that it is easier to get on a node.
*/
if(
//fabs(nodebox.MaxEdge.Y-box.MinEdge.Y) < d
fabs(nodebox.MaxEdge.Y-box.MinEdge.Y) < 0.15*BS
&& nodebox.MaxEdge.X-d > box.MinEdge.X
&& nodebox.MinEdge.X+d < box.MaxEdge.X
&& nodebox.MaxEdge.Z-d > box.MinEdge.Z
&& nodebox.MinEdge.Z+d < box.MaxEdge.Z
){
result.touching_ground = true;
}
// If object doesn't intersect with node, ignore node.
if(box.intersectsWithBox(nodebox) == false)
continue;
/*
Go through every axis
*/
v3f dirs[3] = {
v3f(0,0,1), // back-front
v3f(0,1,0), // top-bottom
v3f(1,0,0), // right-left
};
for(u16 i=0; i<3; i++)
{
/*
Calculate values along the axis
*/
f32 nodemax = nodebox.MaxEdge.dotProduct(dirs[i]);
f32 nodemin = nodebox.MinEdge.dotProduct(dirs[i]);
f32 objectmax = box.MaxEdge.dotProduct(dirs[i]);
f32 objectmin = box.MinEdge.dotProduct(dirs[i]);
f32 objectmax_old = oldbox.MaxEdge.dotProduct(dirs[i]);
f32 objectmin_old = oldbox.MinEdge.dotProduct(dirs[i]);
/*
Check collision for the axis.
Collision happens when object is going through a surface.
*/
bool negative_axis_collides =
(nodemax > objectmin && nodemax <= objectmin_old + d
&& speed_f.dotProduct(dirs[i]) < 0);
bool positive_axis_collides =
(nodemin < objectmax && nodemin >= objectmax_old - d
&& speed_f.dotProduct(dirs[i]) > 0);
bool main_axis_collides =
negative_axis_collides || positive_axis_collides;
/*
Check overlap of object and node in other axes
*/
bool other_axes_overlap = true;
for(u16 j=0; j<3; j++)
{
if(j == i)
continue;
f32 nodemax = nodebox.MaxEdge.dotProduct(dirs[j]);
f32 nodemin = nodebox.MinEdge.dotProduct(dirs[j]);
f32 objectmax = box.MaxEdge.dotProduct(dirs[j]);
f32 objectmin = box.MinEdge.dotProduct(dirs[j]);
if(!(nodemax - d > objectmin && nodemin + d < objectmax))
{
other_axes_overlap = false;
break;
}
}
/*
If this is a collision, revert the pos_f in the main
direction.
*/
if(other_axes_overlap && main_axis_collides)
{
speed_f -= speed_f.dotProduct(dirs[i]) * dirs[i];
pos_f -= pos_f.dotProduct(dirs[i]) * dirs[i];
pos_f += oldpos_f.dotProduct(dirs[i]) * dirs[i];
result.collides = true;
}
}
} // xyz
return result;
}
collisionMoveResult collisionMovePrecise(Map *map, IGameDef *gamedef,
f32 pos_max_d, const core::aabbox3d<f32> &box_0,
f32 dtime, v3f &pos_f, v3f &speed_f)
{
collisionMoveResult final_result;
// If there is no speed, there are no collisions
if(speed_f.getLength() == 0)
return final_result;
// Maximum time increment (for collision detection etc)
// time = distance / speed
f32 dtime_max_increment = pos_max_d / speed_f.getLength();
// Maximum time increment is 10ms or lower
if(dtime_max_increment > 0.01)
dtime_max_increment = 0.01;
// Don't allow overly huge dtime
if(dtime > 2.0)
dtime = 2.0;
f32 dtime_downcount = dtime;
u32 loopcount = 0;
do
{
loopcount++;
f32 dtime_part;
if(dtime_downcount > dtime_max_increment)
{
dtime_part = dtime_max_increment;
dtime_downcount -= dtime_part;
}
else
{
dtime_part = dtime_downcount;
/*
Setting this to 0 (no -=dtime_part) disables an infinite loop
when dtime_part is so small that dtime_downcount -= dtime_part
does nothing
*/
dtime_downcount = 0;
}
collisionMoveResult result = collisionMoveSimple(map, gamedef,
pos_max_d, box_0, dtime_part, pos_f, speed_f);
if(result.touching_ground)
final_result.touching_ground = true;
if(result.collides)
final_result.collides = true;
}
while(dtime_downcount > 0.001);
return final_result;
}
|
