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// physics.cpp: no physics books were hurt nor consulted in the construction of this code.
// All physics computations and constants were invented on the fly and simply tweaked until
// they "felt right", and have no basis in reality. Collision detection is simplistic but
// very robust (uses discrete steps at fixed fps).
// physics.cpp: no physics books were hurt nor consulted in the construction of
// this code. All physics computations and constants were invented on the fly
// and simply tweaked until they "felt right", and have no basis in reality.
// Collision detection is simplistic but very robust (uses discrete steps at
// fixed fps).
#include "cube.h"
bool
bool plcollide(dynent *d, dynent *o, float &headspace, float &hi, float &lo) // collide with player or monster
if(o->state!=CS_ALIVE) return true;
const float r = o->radius+d->radius;
if(fabs(o->o.x-d->o.x)<r && fabs(o->o.y-d->o.y)<r)
{
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; }
else if(o->o.z+o->aboveeye>lo) lo = o->o.z+o->aboveeye+1;
if(fabs(o->o.z-d->o.z)<o->aboveeye+d->eyeheight) return false;
if(d->monsterstate) return false; // hack
headspace = d->o.z-o->o.z-o->aboveeye-d->eyeheight;
if(headspace<0) headspace = 10;
};
return true;
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
sqr *w = wmip[mip];
int sz = ssize>>mip;
bool stest = SOLID(SWS(w, x+dx, y, sz)) && SOLID(SWS(w, x, y+dy, sz));
mip++;
x /= 2;
y /= 2;
if(SWS(wmip[mip], x, y, ssize>>mip)->type==CORNER)
{
bx = x<<mip;
by = y<<mip;
bs = 1<<mip;
return cornertest(mip, x, y, dx, dy, bx, by, bs);
};
return stest;
void mmcollide(dynent *d, float &hi, float &lo) // collide with a mapmodel
loopv(ents)
{
entity &e = ents[i];
if(e.type!=MAPMODEL) continue;
mapmodelinfo &mmi = getmminfo(e.attr2);
if(!&mmi || !mmi.h) continue;
const float r = mmi.rad+d->radius;
if(fabs(e.x-d->o.x)<r && fabs(e.y-d->o.y)<r)
{
float mmz = (float)(S(e.x, e.y)->floor+mmi.zoff+e.attr3);
if(d->o.z-d->eyeheight<mmz) { if(mmz<hi) hi = mmz; }
else if(mmz+mmi.h>lo) lo = mmz+mmi.h;
};
};
// drop & rise are supplied by the physics below to indicate gravity/push for current mini-timestep
// drop & rise are supplied by the physics below to indicate gravity/push for
// current mini-timestep
bool
bool collide(dynent *d, bool spawn, float drop, float rise)
const float fx1 = d->o.x-d->radius; // figure out integer cube rectangle this entity covers in map
const float fy1 = d->o.y-d->radius;
const float fx2 = d->o.x+d->radius;
const float fy2 = d->o.y+d->radius;
const int x1 = fast_f2nat(fx1);
const int y1 = fast_f2nat(fy1);
const int x2 = fast_f2nat(fx2);
const int y2 = fast_f2nat(fy2);
float hi = 127, lo = -128;
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 :)
for(int x = x1; x<=x2; x++) for(int y = y1; y<=y2; y++) // collide with map
{
if(OUTBORD(x,y)) return false;
sqr *s = S(x,y);
float ceil = s->ceil;
float floor = s->floor;
switch(s->type)
{
case SOLID:
return false;
case CORNER:
{
int bx = x, by = y, bs = 1;
if(x==x1 && y==y1 && cornertest(0, x, y, -1, -1, bx, by, bs) && fx1-bx+fy1-by<=bs
|| x==x2 && y==y1 && cornertest(0, x, y, 1, -1, bx, by, bs) && fx2-bx>=fy1-by
|| x==x1 && y==y2 && cornertest(0, x, y, -1, 1, bx, by, bs) && fx1-bx<=fy2-by
|| x==x2 && y==y2 && cornertest(0, x, y, 1, 1, bx, by, bs) && fx2-bx+fy2-by>=bs)
return false;
break;
};
case FHF: // FIXME: too simplistic collision with slopes, makes it feels like tiny stairs
floor -= (s->vdelta+S(x+1,y)->vdelta+S(x,y+1)->vdelta+S(x+1,y+1)->vdelta)/16.0f;
break;
// slopes, makes it feels like tiny stairs
floor -= (s->vdelta + S(x + 1, y)->vdelta +
S(x, y + 1)->vdelta +
S(x + 1, y + 1)->vdelta) /
16.0f;
break;
case CHF:
ceil += (s->vdelta+S(x+1,y)->vdelta+S(x,y+1)->vdelta+S(x+1,y+1)->vdelta)/16.0f;
};
if(ceil<hi) hi = ceil;
if(floor>lo) lo = floor;
if(floor<minfloor) return false;
};
if(hi-lo < d->eyeheight+d->aboveeye) return false;
float headspace = 10;
loopv(players) // collide with other players
{
dynent *o = players[i];
if(!o || o==d) continue;
if(!plcollide(d, o, headspace, hi, lo)) return false;
};
if(d!=player1) if(!plcollide(d, player1, headspace, hi, lo)) return false;
dvector &v = getmonsters();
// this loop can be a performance bottleneck with many monster on a slow cpu,
// should replace with a blockmap but seems mostly fast enough
loopv(v) if(!vreject(d->o, v[i]->o, 7.0f) && d!=v[i] && !plcollide(d, v[i], headspace, hi, lo)) return false;
headspace -= 0.01f;
mmcollide(d, hi, lo); // collide with map models
if(spawn)
{
d->o.z = lo+d->eyeheight; // just drop to floor (sideeffect)
d->onfloor = true;
}
else
{
const float space = d->o.z-d->eyeheight-lo;
if(space<0)
{
if(space>-0.01) d->o.z = lo+d->eyeheight; // stick on step
else if(space>-1.26f) d->o.z += rise; // rise thru stair
else return false;
}
else
{
d->o.z -= min(min(drop, space), headspace); // gravity
};
const float space2 = hi-(d->o.z+d->aboveeye);
if(space2<0)
{
if(space2<-0.1) return false; // hack alert!
d->o.z = hi-d->aboveeye; // glue to ceiling
d->vel.z = 0; // cancel out jumping velocity
};
d->onfloor = d->o.z-d->eyeheight-lo<0.001f;
};
return true;
float rad(float x) { return x*3.14159f/180; };
void physicsframe() // optimally schedule physics frames inside the graphics frames
if(curtime>=MINFRAMETIME)
{
int faketime = curtime+physicsfraction;
physicsrepeat = faketime/MINFRAMETIME;
physicsfraction = faketime-physicsrepeat*MINFRAMETIME;
}
else
{
physicsrepeat = 1;
};
// moveres indicated the physics precision (which is lower for monsters and multiplayer prediction)
// local is false for multiplayer prediction
// moveres indicated the physics precision (which is lower for monsters and
// multiplayer prediction) local is false for multiplayer prediction
void
void moveplayer(dynent *pl, int moveres, bool local, int curtime)
const bool water = hdr.waterlevel>pl->o.z-0.5f;
const bool floating = (editmode && local) || pl->state==CS_EDITING;
vec d; // vector of direction we ideally want to move in
d.x = (float)(pl->move*cos(rad(pl->yaw-90)));
d.y = (float)(pl->move*sin(rad(pl->yaw-90)));
d.z = 0;
if(floating || water)
{
d.x *= (float)cos(rad(pl->pitch));
d.y *= (float)cos(rad(pl->pitch));
d.z = (float)(pl->move*sin(rad(pl->pitch)));
};
d.x += (float)(pl->strafe*cos(rad(pl->yaw-180)));
d.y += (float)(pl->strafe*sin(rad(pl->yaw-180)));
const float speed = curtime/(water ? 2000.0f : 1000.0f)*pl->maxspeed;
const float friction = water ? 20.0f : (pl->onfloor || floating ? 6.0f : 30.0f);
const float fpsfric = friction/curtime*20.0f;
vmul(pl->vel, fpsfric-1); // slowly apply friction and direction to velocity, gives a smooth movement
vadd(pl->vel, d);
vdiv(pl->vel, fpsfric);
d = pl->vel;
vmul(d, speed); // d is now frametime based velocity vector
pl->blocked = false;
pl->moving = true;
if(floating) // just apply velocity
{
vadd(pl->o, d);
if(pl->jumpnext) { pl->jumpnext = false; pl->vel.z = 2; }
}
else // apply velocity with collision
{
if(pl->onfloor || water)
{
if(pl->jumpnext)
{
pl->jumpnext = false;
pl->vel.z = 1.7f; // physics impulse upwards
if(water) { pl->vel.x /= 8; pl->vel.y /= 8; }; // dampen velocity change even harder, gives correct water feel
if(local) playsoundc(S_JUMP);
else if(pl->monsterstate) playsound(S_JUMP, &pl->o);
}
else if(pl->timeinair>800) // if we land after long time must have been a high jump, make thud sound
{
if(local) playsoundc(S_LAND);
else if(pl->monsterstate) playsound(S_LAND, &pl->o);
};
pl->timeinair = 0;
}
else
{
pl->timeinair += curtime;
};
const float gravity = 20;
const float f = 1.0f/moveres;
float dropf = ((gravity-1)+pl->timeinair/15.0f); // incorrect, but works fine
if(water) { dropf = 5; pl->timeinair = 0; }; // float slowly down in water
const float drop = dropf*curtime/gravity/100/moveres; // at high fps, gravity kicks in too fast
const float rise = speed/moveres/1.2f; // extra smoothness when lifting up stairs
loopi(moveres) // discrete steps collision detection & sliding
{
// try move forward
pl->o.x += f*d.x;
pl->o.y += f*d.y;
pl->o.z += f*d.z;
if(collide(pl, false, drop, rise)) continue;
// player stuck, try slide along y axis
pl->blocked = true;
pl->o.x -= f*d.x;
if(collide(pl, false, drop, rise)) { d.x = 0; continue; };
pl->o.x += f*d.x;
// still stuck, try x axis
pl->o.y -= f*d.y;
if(collide(pl, false, drop, rise)) { d.y = 0; continue; };
pl->o.y += f*d.y;
// try just dropping down
pl->moving = false;
pl->o.x -= f*d.x;
pl->o.y -= f*d.y;
if(collide(pl, false, drop, rise)) { d.y = d.x = 0; continue; };
pl->o.z -= f*d.z;
break;
};
};
// detect wether player is outside map, used for skipping zbuffer clear mostly
if(pl->o.x < 0 || pl->o.x >= ssize || pl->o.y <0 || pl->o.y > ssize)
{
pl->outsidemap = true;
}
else
{
sqr *s = S((int)pl->o.x, (int)pl->o.y);
pl->outsidemap = SOLID(s)
|| pl->o.z < s->floor - (s->type==FHF ? s->vdelta/4 : 0)
|| pl->o.z > s->ceil + (s->type==CHF ? s->vdelta/4 : 0);
};
// automatically apply smooth roll when strafing
if(pl->strafe==0)
{
pl->roll = pl->roll/(1+(float)sqrt((float)curtime)/25);
}
else
{
pl->roll += pl->strafe*curtime/-30.0f;
if(pl->roll>maxroll) pl->roll = (float)maxroll;
if(pl->roll<-maxroll) pl->roll = (float)-maxroll;
};
// play sounds on water transitions
if(!pl->inwater && water) { playsound(S_SPLASH2, &pl->o); pl->vel.z = 0; }
else if(pl->inwater && !water) playsound(S_SPLASH1, &pl->o);
pl->inwater = water;
void moveplayer(dynent *pl, int moveres, bool local)
loopi(physicsrepeat) moveplayer(pl, moveres, local, i ? curtime/physicsrepeat : curtime-curtime/physicsrepeat*(physicsrepeat-1));
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