// 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"
#import "DynamicEntity.h"
#import "Entity.h"
#import "MapModelInfo.h"
// collide with player or monster
bool
plcollide(
DynamicEntity *d, DynamicEntity *o, float &headspace, float &hi, float &lo)
{
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(DynamicEntity *d, float &hi, float &lo) // collide with a mapmodel
{
for (Entity *e in ents) {
if (e.type != MAPMODEL)
continue;
MapModelInfo *mmi = getmminfo(e.attr2);
if (mmi == nil || !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;
}
}
}
// all collision happens here
// spawn is a dirty side effect used in spawning
// drop & rise are supplied by the physics below to indicate gravity/push for
// current mini-timestep
bool
collide(DynamicEntity *d, bool spawn, float drop, float rise)
{
// figure out integer cube rectangle this entity covers in map
const float fx1 = d.o.x - d.radius;
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;
// big monsters are afraid of heights, unless angry :)
float minfloor = (d.monsterstate && !spawn && d.health > 100)
? d.o.z - d.eyeheight - 4.5f
: -1000.0f;
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;
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;
for (id player in players) {
if (player == [OFNull null] || player == d)
continue;
if (!plcollide(d, player, headspace, hi, lo))
return false;
}
if (d != player1)
if (!plcollide(d, player1, headspace, hi, lo))
return false;
// this loop can be a performance bottleneck with many monster on a slow
// cpu, should replace with a blockmap but seems mostly fast enough
for (DynamicEntity *monster in getmonsters())
if (!vreject(d.o, monster.o, 7.0f) && d != monster &&
!plcollide(d, monster, headspace, hi, lo))
return false;
headspace -= 0.01f;
mmcollide(d, hi, lo); // collide with map models
if (spawn) {
// just drop to floor (sideeffect)
d.o = OFMakeVector3D(d.o.x, d.o.y, lo + d.eyeheight);
d.onfloor = true;
} else {
const float space = d.o.z - d.eyeheight - lo;
if (space < 0) {
if (space > -0.01)
// stick on step
d.o = OFMakeVector3D(
d.o.x, d.o.y, lo + d.eyeheight);
else if (space > -1.26f)
// rise thru stair
d.o =
OFMakeVector3D(d.o.x, d.o.y, d.o.z + rise);
else
return false;
} else
// gravity
d.o = OFMakeVector3D(d.o.x, d.o.y,
d.o.z - min(min(drop, space), headspace));
const float space2 = hi - (d.o.z + d.aboveeye);
if (space2 < 0) {
if (space2 < -0.1)
return false; // hack alert!
// glue to ceiling
d.o = OFMakeVector3D(d.o.x, d.o.y, hi - d.aboveeye);
// cancel out jumping velocity
d.vel = OFMakeVector3D(d.vel.x, d.vel.y, 0);
}
d.onfloor = d.o.z - d.eyeheight - lo < 0.001f;
}
return true;
}
float
rad(float x)
{
return x * 3.14159f / 180;
}
VARP(maxroll, 0, 3, 20);
int physicsfraction = 0, physicsrepeat = 0;
const int MINFRAMETIME = 20; // physics always simulated at 50fps or better
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;
}
}
// main physics routine, moves a player/monster for a curtime step
// moveres indicated the physics precision (which is lower for monsters and
// multiplayer prediction) local is false for multiplayer prediction
void
moveplayer(DynamicEntity *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;
OFVector3D 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;
// slowly apply friction and direction to
// velocity, gives a smooth movement
vmul(pl.vel, fpsfric - 1);
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 = OFMakeVector3D(pl.vel.x, pl.vel.y, 2);
}
} else {
// apply velocity with collision
if (pl.onfloor || water) {
if (pl.jumpnext) {
pl.jumpnext = false;
// physics impulse upwards
pl.vel =
OFMakeVector3D(pl.vel.x, pl.vel.y, 1.7);
// dampen velocity change even harder, gives
// correct water feel
if (water)
pl.vel = OFMakeVector3D(pl.vel.x / 8,
pl.vel.y / 8, pl.vel.z);
if (local)
playsoundc(S_JUMP);
else if (pl.monsterstate) {
OFVector3D loc = pl.o;
playsound(S_JUMP, &loc);
}
} 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) {
OFVector3D loc = pl.o;
playsound(S_LAND, &loc);
}
}
pl.timeinair = 0;
} else
pl.timeinair += curtime;
const float gravity = 20;
const float f = 1.0f / moveres;
// incorrect, but works fine
float dropf = ((gravity - 1) + pl.timeinair / 15.0f);
// float slowly down in water
if (water) {
dropf = 5;
pl.timeinair = 0;
}
// at high fps, gravity kicks in too fast
const float drop = dropf * curtime / gravity / 100 / moveres;
// extra smoothness when lifting up stairs
const float rise = speed / moveres / 1.2f;
loopi(moveres) // discrete steps collision detection & sliding
{
// try move forward
pl.o = OFMakeVector3D(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 = OFMakeVector3D(pl.o.x - f * d.x, pl.o.y, pl.o.z);
if (collide(pl, false, drop, rise)) {
d.x = 0;
continue;
}
// still stuck, try x axis
pl.o = OFMakeVector3D(
pl.o.x + f * d.x, pl.o.y - f * d.y, pl.o.z);
if (collide(pl, false, drop, rise)) {
d.y = 0;
continue;
}
// try just dropping down
pl.moving = false;
pl.o = OFMakeVector3D(pl.o.x - f * d.x, pl.o.y, pl.o.z);
if (collide(pl, false, drop, rise)) {
d.y = d.x = 0;
continue;
}
pl.o = OFMakeVector3D(pl.o.x, pl.o.y, 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) {
OFVector3D loc = pl.o;
playsound(S_SPLASH2, &loc);
pl.vel = OFMakeVector3D(pl.vel.x, pl.vel.y, 0);
} else if (pl.inwater && !water) {
OFVector3D loc = pl.o;
playsound(S_SPLASH1, &loc);
}
pl.inwater = water;
}
void
moveplayer(DynamicEntity *pl, int moveres, bool local)
{
loopi(physicsrepeat) moveplayer(pl, moveres, local,
i ? curtime / physicsrepeat
: curtime - curtime / physicsrepeat * (physicsrepeat - 1));
}