1 // physics.cpp: no physics books were hurt nor consulted in the construction of this code.
2 // All physics computations and constants were invented on the fly and simply tweaked until
3 // they "felt right", and have no basis in reality. Collision detection is simplistic but
4 // very robust (uses discrete steps at fixed fps).
5
6 #include "cube.h"
7
plcollide(dynent * d,dynent * o,float & headspace,float & hi,float & lo)8 bool plcollide(dynent *d, dynent *o, float &headspace, float &hi, float &lo) // collide with player or monster
9 {
10 if(o->state!=CS_ALIVE) return true;
11 const float r = o->radius+d->radius;
12 if(fabs(o->o.x-d->o.x)<r && fabs(o->o.y-d->o.y)<r)
13 {
14 if(d->o.z-d->eyeheight<o->o.z-o->eyeheight) { if(o->o.z-o->eyeheight<hi) hi = o->o.z-o->eyeheight-1; }
15 else if(o->o.z+o->aboveeye>lo) lo = o->o.z+o->aboveeye+1;
16
17 if(fabs(o->o.z-d->o.z)<o->aboveeye+d->eyeheight) return false;
18 if(d->monsterstate) return false; // hack
19 headspace = d->o.z-o->o.z-o->aboveeye-d->eyeheight;
20 if(headspace<0) headspace = 10;
21 };
22 return true;
23 };
24
cornertest(int mip,int x,int y,int dx,int dy,int & bx,int & by,int & bs)25 bool cornertest(int mip, int x, int y, int dx, int dy, int &bx, int &by, int &bs) // recursively collide with a mipmapped corner cube
26 {
27 sqr *w = wmip[mip];
28 int sz = ssize>>mip;
29 bool stest = SOLID(SWS(w, x+dx, y, sz)) && SOLID(SWS(w, x, y+dy, sz));
30 mip++;
31 x /= 2;
32 y /= 2;
33 if(SWS(wmip[mip], x, y, ssize>>mip)->type==CORNER)
34 {
35 bx = x<<mip;
36 by = y<<mip;
37 bs = 1<<mip;
38 return cornertest(mip, x, y, dx, dy, bx, by, bs);
39 };
40 return stest;
41 };
42
mmcollide(dynent * d,float & hi,float & lo)43 void mmcollide(dynent *d, float &hi, float &lo) // collide with a mapmodel
44 {
45 loopv(ents)
46 {
47 entity &e = ents[i];
48 if(e.type!=MAPMODEL) continue;
49 mapmodelinfo *mmi = getmminfo(e.attr2);
50 if(!mmi || !mmi->h) continue;
51 const float r = mmi->rad+d->radius;
52 if(fabs(e.x-d->o.x)<r && fabs(e.y-d->o.y)<r)
53 {
54 float mmz = (float)(S(e.x, e.y)->floor+mmi->zoff+e.attr3);
55 if(d->o.z-d->eyeheight<mmz) { if(mmz<hi) hi = mmz; }
56 else if(mmz+mmi->h>lo) lo = mmz+mmi->h;
57 };
58 };
59 };
60
61 // all collision happens here
62 // spawn is a dirty side effect used in spawning
63 // drop & rise are supplied by the physics below to indicate gravity/push for current mini-timestep
64
collide(dynent * d,bool spawn,float drop,float rise)65 bool collide(dynent *d, bool spawn, float drop, float rise)
66 {
67 const float fx1 = d->o.x-d->radius; // figure out integer cube rectangle this entity covers in map
68 const float fy1 = d->o.y-d->radius;
69 const float fx2 = d->o.x+d->radius;
70 const float fy2 = d->o.y+d->radius;
71 const int x1 = fast_f2nat(fx1);
72 const int y1 = fast_f2nat(fy1);
73 const int x2 = fast_f2nat(fx2);
74 const int y2 = fast_f2nat(fy2);
75 float hi = 127, lo = -128;
76 float minfloor = (d->monsterstate && !spawn && d->health>100) ? d->o.z-d->eyeheight-4.5f : -1000.0f; // big monsters are afraid of heights, unless angry :)
77
78 for(int x = x1; x<=x2; x++) for(int y = y1; y<=y2; y++) // collide with map
79 {
80 if(OUTBORD(x,y)) return false;
81 sqr *s = S(x,y);
82 float ceil = s->ceil;
83 float floor = s->floor;
84 switch(s->type)
85 {
86 case SOLID:
87 return false;
88
89 case CORNER:
90 {
91 int bx = x, by = y, bs = 1;
92 if(x==x1 && y==y1 && cornertest(0, x, y, -1, -1, bx, by, bs) && fx1-bx+fy1-by<=bs
93 || x==x2 && y==y1 && cornertest(0, x, y, 1, -1, bx, by, bs) && fx2-bx>=fy1-by
94 || x==x1 && y==y2 && cornertest(0, x, y, -1, 1, bx, by, bs) && fx1-bx<=fy2-by
95 || x==x2 && y==y2 && cornertest(0, x, y, 1, 1, bx, by, bs) && fx2-bx+fy2-by>=bs)
96 return false;
97 break;
98 };
99
100 case FHF: // FIXME: too simplistic collision with slopes, makes it feels like tiny stairs
101 floor -= (s->vdelta+S(x+1,y)->vdelta+S(x,y+1)->vdelta+S(x+1,y+1)->vdelta)/16.0f;
102 break;
103
104 case CHF:
105 ceil += (s->vdelta+S(x+1,y)->vdelta+S(x,y+1)->vdelta+S(x+1,y+1)->vdelta)/16.0f;
106
107 };
108 if(ceil<hi) hi = ceil;
109 if(floor>lo) lo = floor;
110 if(floor<minfloor) return false;
111 };
112
113 if(hi-lo < d->eyeheight+d->aboveeye) return false;
114
115 float headspace = 10;
116 loopv(players) // collide with other players
117 {
118 dynent *o = players[i];
119 if(!o || o==d) continue;
120 if(!plcollide(d, o, headspace, hi, lo)) return false;
121 };
122 if(d!=player1) if(!plcollide(d, player1, headspace, hi, lo)) return false;
123 dvector &v = getmonsters();
124 // this loop can be a performance bottleneck with many monster on a slow cpu,
125 // should replace with a blockmap but seems mostly fast enough
126 loopv(v) if(!vreject(d->o, v[i]->o, 7.0f) && d!=v[i] && !plcollide(d, v[i], headspace, hi, lo)) return false;
127 headspace -= 0.01f;
128
129 mmcollide(d, hi, lo); // collide with map models
130
131 if(spawn)
132 {
133 d->o.z = lo+d->eyeheight; // just drop to floor (sideeffect)
134 d->onfloor = true;
135 }
136 else
137 {
138 const float space = d->o.z-d->eyeheight-lo;
139 if(space<0)
140 {
141 if(space>-0.01) d->o.z = lo+d->eyeheight; // stick on step
142 else if(space>-1.26f) d->o.z += rise; // rise thru stair
143 else return false;
144 }
145 else
146 {
147 d->o.z -= min(min(drop, space), headspace); // gravity
148 };
149
150 const float space2 = hi-(d->o.z+d->aboveeye);
151 if(space2<0)
152 {
153 if(space2<-0.1) return false; // hack alert!
154 d->o.z = hi-d->aboveeye; // glue to ceiling
155 d->vel.z = 0; // cancel out jumping velocity
156 };
157
158 d->onfloor = d->o.z-d->eyeheight-lo<0.001f;
159 };
160 return true;
161 }
162
rad(float x)163 float rad(float x) { return x*3.14159f/180; };
164
165 VARP(maxroll, 0, 3, 20);
166
167 int physicsfraction = 0, physicsrepeat = 0;
168 const int MINFRAMETIME = 20; // physics always simulated at 50fps or better
169
physicsframe()170 void physicsframe() // optimally schedule physics frames inside the graphics frames
171 {
172 if(curtime>=MINFRAMETIME)
173 {
174 int faketime = curtime+physicsfraction;
175 physicsrepeat = faketime/MINFRAMETIME;
176 physicsfraction = faketime-physicsrepeat*MINFRAMETIME;
177 }
178 else
179 {
180 physicsrepeat = 1;
181 };
182 };
183
184 // main physics routine, moves a player/monster for a curtime step
185 // moveres indicated the physics precision (which is lower for monsters and multiplayer prediction)
186 // local is false for multiplayer prediction
187
moveplayer(dynent * pl,int moveres,bool local,int curtime)188 void moveplayer(dynent *pl, int moveres, bool local, int curtime)
189 {
190 const bool water = hdr.waterlevel>pl->o.z-0.5f;
191 const bool floating = (editmode && local) || pl->state==CS_EDITING;
192
193 vec d; // vector of direction we ideally want to move in
194
195 d.x = (float)(pl->move*cos(rad(pl->yaw-90)));
196 d.y = (float)(pl->move*sin(rad(pl->yaw-90)));
197 d.z = 0;
198
199 if(floating || water)
200 {
201 d.x *= (float)cos(rad(pl->pitch));
202 d.y *= (float)cos(rad(pl->pitch));
203 d.z = (float)(pl->move*sin(rad(pl->pitch)));
204 };
205
206 d.x += (float)(pl->strafe*cos(rad(pl->yaw-180)));
207 d.y += (float)(pl->strafe*sin(rad(pl->yaw-180)));
208
209 const float speed = curtime/(water ? 2000.0f : 1000.0f)*pl->maxspeed;
210 const float friction = water ? 20.0f : (pl->onfloor || floating ? 6.0f : 30.0f);
211
212 const float fpsfric = friction/curtime*20.0f;
213
214 vmul(pl->vel, fpsfric-1); // slowly apply friction and direction to velocity, gives a smooth movement
215 vadd(pl->vel, d);
216 vdiv(pl->vel, fpsfric);
217 d = pl->vel;
218 vmul(d, speed); // d is now frametime based velocity vector
219
220 pl->blocked = false;
221 pl->moving = true;
222
223 if(floating) // just apply velocity
224 {
225 vadd(pl->o, d);
226 if(pl->jumpnext) { pl->jumpnext = false; pl->vel.z = 2; }
227 }
228 else // apply velocity with collision
229 {
230 if(pl->onfloor || water)
231 {
232 if(pl->jumpnext)
233 {
234 pl->jumpnext = false;
235 pl->vel.z = 1.7f; // physics impulse upwards
236 if(water) { pl->vel.x /= 8; pl->vel.y /= 8; }; // dampen velocity change even harder, gives correct water feel
237 if(local) playsoundc(S_JUMP);
238 else if(pl->monsterstate) playsound(S_JUMP, &pl->o);
239 }
240 else if(pl->timeinair>800) // if we land after long time must have been a high jump, make thud sound
241 {
242 if(local) playsoundc(S_LAND);
243 else if(pl->monsterstate) playsound(S_LAND, &pl->o);
244 };
245 pl->timeinair = 0;
246 }
247 else
248 {
249 pl->timeinair += curtime;
250 };
251
252 const float gravity = 20;
253 const float f = 1.0f/moveres;
254 float dropf = ((gravity-1)+pl->timeinair/15.0f); // incorrect, but works fine
255 if(water) { dropf = 5; pl->timeinair = 0; }; // float slowly down in water
256 const float drop = dropf*curtime/gravity/100/moveres; // at high fps, gravity kicks in too fast
257 const float rise = speed/moveres/1.2f; // extra smoothness when lifting up stairs
258
259 loopi(moveres) // discrete steps collision detection & sliding
260 {
261 // try move forward
262 pl->o.x += f*d.x;
263 pl->o.y += f*d.y;
264 pl->o.z += f*d.z;
265 if(collide(pl, false, drop, rise)) continue;
266 // player stuck, try slide along y axis
267 pl->blocked = true;
268 pl->o.x -= f*d.x;
269 if(collide(pl, false, drop, rise)) { d.x = 0; continue; };
270 pl->o.x += f*d.x;
271 // still stuck, try x axis
272 pl->o.y -= f*d.y;
273 if(collide(pl, false, drop, rise)) { d.y = 0; continue; };
274 pl->o.y += f*d.y;
275 // try just dropping down
276 pl->moving = false;
277 pl->o.x -= f*d.x;
278 pl->o.y -= f*d.y;
279 if(collide(pl, false, drop, rise)) { d.y = d.x = 0; continue; };
280 pl->o.z -= f*d.z;
281 break;
282 };
283 };
284
285 // detect wether player is outside map, used for skipping zbuffer clear mostly
286
287 if(pl->o.x < 0 || pl->o.x >= ssize || pl->o.y <0 || pl->o.y > ssize)
288 {
289 pl->outsidemap = true;
290 }
291 else
292 {
293 sqr *s = S((int)pl->o.x, (int)pl->o.y);
294 pl->outsidemap = SOLID(s)
295 || pl->o.z < s->floor - (s->type==FHF ? s->vdelta/4 : 0)
296 || pl->o.z > s->ceil + (s->type==CHF ? s->vdelta/4 : 0);
297 };
298
299 // automatically apply smooth roll when strafing
300
301 if(pl->strafe==0)
302 {
303 pl->roll = pl->roll/(1+(float)sqrt((float)curtime)/25);
304 }
305 else
306 {
307 pl->roll += pl->strafe*curtime/-30.0f;
308 if(pl->roll>maxroll) pl->roll = (float)maxroll;
309 if(pl->roll<-maxroll) pl->roll = (float)-maxroll;
310 };
311
312 // play sounds on water transitions
313
314 if(!pl->inwater && water) { playsound(S_SPLASH2, &pl->o); pl->vel.z = 0; }
315 else if(pl->inwater && !water) playsound(S_SPLASH1, &pl->o);
316 pl->inwater = water;
317 };
318
moveplayer(dynent * pl,int moveres,bool local)319 void moveplayer(dynent *pl, int moveres, bool local)
320 {
321 loopi(physicsrepeat) moveplayer(pl, moveres, local, i ? curtime/physicsrepeat : curtime-curtime/physicsrepeat*(physicsrepeat-1));
322 };
323
324