g_move.cpp

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/*
Copyright (C) 2002-2025 UFO: Alien Invasion.
 
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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 
*/
 
#include "g_move.h"
#include "g_actor.h"
#include "g_client.h"
#include "g_combat.h"
#include "g_edicts.h"
#include "g_health.h"
#include "g_inventory.h"
#include "g_reaction.h"
#include "g_utils.h"
#include "g_vis.h"
#include "g_match.h"
 
#define ACTOR_SPEED_NORMAL 100
#define ACTOR_SPEED_CROUCHED (ACTOR_SPEED_NORMAL / 2)
static const float FALLING_DAMAGE_FACTOR = 10.0f;

static forbiddenList_t forbiddenList;

static void G_BuildForbiddenList (int team, const Edict* movingActor)
{
    forbiddenList.reset();
 
    /* team visibility */
    const teammask_t teamMask = team ? G_TeamToVisMask(team) : TEAM_ALL;
 
    Edict* ent = nullptr;
    while ((ent = G_EdictsGetNextInUse(ent))) {
        /* Dead 2x2 unit will stop walking, too. */
        if (G_IsBlockingMovementActor(ent) && (G_IsAI(movingActor) || (ent->visflags & teamMask))) {
            forbiddenList.add(ent->pos, (byte*) &ent->fieldSize);
        } else if (ent->type == ET_SOLID) {
            for (int j = 0; j < ent->forbiddenListSize; j++) {
                forbiddenList.add(ent->forbiddenListPos[j], (byte*) &ent->fieldSize);
            }
        }
    }
}

void G_MoveCalc (int team, const Actor* movingActor, const pos3_t from, int distance)
{
    G_MoveCalcLocal(level.pathingMap, team, movingActor, from, distance);
}

void G_MoveCalcLocal (pathing_t* pt, int team, const Edict* movingActor, const pos3_t from, int distance)
{
    G_BuildForbiddenList(team, movingActor);
    gi.GridCalcPathing(movingActor->fieldSize, pt, from, distance, &forbiddenList);
}
 
bool G_FindPath (int team, const Edict* movingActor, const pos3_t from, const pos3_t targetPos, bool crouched, int maxTUs)
{
    G_BuildForbiddenList(team, movingActor);
    return gi.GridFindPath(movingActor->fieldSize, level.pathingMap, from, targetPos, crouched, maxTUs, &forbiddenList);
}

void G_ActorFall (Edict* ent)
{
    const pos_t oldZ = ent->pos[2];
 
    ent->pos[2] = gi.GridFall(ent->fieldSize, ent->pos);
 
    if (oldZ == ent->pos[2])
        return;
 
    Edict* entAtPos = G_GetEdictFromPos(ent->pos, ET_NULL);
    if (entAtPos != nullptr && (G_IsBreakable(entAtPos) || G_IsBlockingMovementActor(entAtPos))) {
        const int diff = oldZ - ent->pos[2];
        G_TakeDamage(entAtPos, (int)(FALLING_DAMAGE_FACTOR * (float)diff));
    }
 
    ent->calcOrigin();
    gi.LinkEdict(ent);
 
    G_CheckVis(ent);
 
    G_EventActorFall(*ent);
 
    G_EventEnd();
}

static bool G_ActorShouldStopInMidMove (const Edict* ent, int visState, dvec_t* dvtab, int max)
{
    if (visState & VIS_STOP)
        return true;
 
    /* check that the appearing unit is not on a grid position the actor wanted to walk to.
     * this might be the case if the edict got visible in mid mode */
    if (visState & VIS_APPEAR) {
        pos3_t pos;
        VectorCopy(ent->pos, pos);
        while (max >= 0) {
            int tmp = 0;
 
            PosAddDV(pos, tmp, dvtab[max]);
            max--;
            const Actor* blockEdict = G_EdictsGetLivingActorFromPos(pos);
 
            if (blockEdict && G_IsBlockingMovementActor(blockEdict)) {
                const bool visible = G_IsVisibleForTeam(blockEdict, ent->getTeam());
                if (visible)
                    return true;
            }
        }
    }
    return false;
}
 
static void G_SendFootstepSound (Edict* ent, const int contentFlags)
{
    const char* snd = nullptr;
 
    if (contentFlags & CONTENTS_WATER) {
        if (ent->contentFlags & CONTENTS_WATER) {
            /* looks like we already are in the water */
            /* send water moving sound */
            snd = "footsteps/water_under";
        } else {
            /* send water entering sound */
            snd = "footsteps/water_in";
        }
    } else if (ent->contentFlags & CONTENTS_WATER) {
        /* send water leaving sound */
        snd = "footsteps/water_out";
    } else if (Q_strvalid(ent->chr.teamDef->footstepSound)) {
        /* some teams have a fixed footstep or moving sound */
        snd = ent->chr.teamDef->footstepSound;
    } else {
        /* we should really hit the ground with this */
        const vec3_t to = {ent->origin[0], ent->origin[1], ent->origin[2] - UNIT_HEIGHT};
        const trace_t trace = G_Trace(Line(ent->origin, to), nullptr, MASK_SOLID);
        if (trace.surface) {
            snd = gi.GetFootstepSound(trace.surface->name);
        }
    }
    if (snd != nullptr) {
        G_EventSpawnFootstepSound(*ent, snd);
    }
}

static void G_WriteStep (Actor* ent, const int dvec, const int contentFlags)
{
    /* write move header if not yet done */
    if (gi.GetEvent() != EV_ACTOR_MOVE) {
        G_EventAdd(PM_ALL, EV_ACTOR_MOVE, ent->getIdNum());
    }
 
    if (ent->moveinfo.steps >= MAX_ROUTE) {
        ent->moveinfo.steps = 0;
    }
    gi.WriteByte(ent->moveinfo.steps);
 
    /* write move header and always one step after another - because the next step
     * might already be the last one due to some stop event */
    gi.WriteShort(dvec);
    gi.WriteShort(ent->speed);
    gi.WriteShort(contentFlags);
 
    /* Send the sound effect to everyone who's not seeing the actor */
    if (!ent->isCrouched()) {
        G_SendFootstepSound(ent, contentFlags);
    }
 
    ent->contentFlags = contentFlags;
 
    ent->moveinfo.steps++;
}
 
int G_FillDirectionTable (dvec_t* dvtab, size_t dvtabSize, byte crouchingState, pos3_t pos)
{
    int dvec;
    int numdv = 0;
    while ((dvec = gi.MoveNext(level.pathingMap, pos, crouchingState)) != ROUTING_UNREACHABLE) {
        const int oldZ = pos[2];
        /* dvec indicates the direction traveled to get to the new cell and the original cell height. */
        /* We are going backwards to the origin. */
        PosSubDV(pos, crouchingState, dvec);
        /* Replace the z portion of the DV value so we can get back to where we were. */
        dvtab[numdv++] = setDVz(dvec, oldZ);
        if (numdv >= dvtabSize)
            break;
    }
 
    return numdv;
}

pos_t G_ActorMoveLength (const Actor* actor, const pathing_t* path, const pos3_t to, bool stored)
{
    byte crouchingState = actor->isCrouched() ? 1 : 0;
    const pos_t length = gi.MoveLength(path, to, crouchingState, stored);
 
    if (!length || length == ROUTING_NOT_REACHABLE)
        return length;
 
    pos3_t pos;
    VectorCopy(to, pos);
    int dvec, numSteps = 0;
    while ((dvec = gi.MoveNext(level.pathingMap, pos, crouchingState)) != ROUTING_UNREACHABLE) {
        ++numSteps;
        PosSubDV(pos, crouchingState, dvec); /* We are going backwards to the origin. */
    }
 
    const bool useAutostand = crouchingState && (G_IsAI(actor) || actor->getPlayer().autostand)
                && gi.GridShouldUseAutostand(path, to);
    const int autostandTU = useAutostand ? 2 * TU_CROUCH : 0;
 
    return std::min(ROUTING_NOT_REACHABLE, length + static_cast<int>(numSteps *
            G_ActorGetInjuryPenalty(actor, MODIFIER_MOVEMENT)) + autostandTU);
}

void G_ClientMove (const Player& player, int visTeam, Actor* actor, const pos3_t to)
{
    if (VectorCompare(actor->pos, to))
        return;
 
    /* check if action is possible */
    if (!G_ActionCheckForCurrentTeam(player, actor, TU_MOVE_STRAIGHT))
        return;
 
    bool autoCrouchRequired = false;
    byte crouchingState = actor->isCrouched() ? 1 : 0;
 
    /* calculate move table */
    G_MoveCalc(visTeam, actor, actor->pos, actor->TU);
 
    /* Autostand: check if the actor is crouched and player wants autostanding...*/
    if (crouchingState && (G_IsAI(actor) || player.autostand)) {
        /* ...and if this is a long walk... */
        if (gi.CanActorStandHere(actor->fieldSize, actor->pos)
            && gi.GridShouldUseAutostand(level.pathingMap, to)) {
            /* ...make them stand first. If the player really wants them to walk a long
             * way crouched, he can move the actor in several stages.
             * Uses the threshold at which standing, moving and crouching again takes
             * fewer TU than just crawling while crouched. */
            G_ClientStateChange(player, actor, STATE_CROUCHED, true); /* change to stand state */
            crouchingState = actor->isCrouched() ? 1 : 0;
            if (!crouchingState)
                autoCrouchRequired = true;
        }
    }
 
    const pos_t length = std::min(G_ActorMoveLength(actor, level.pathingMap, to, false)
                + (autoCrouchRequired ? TU_CROUCH : 0), ROUTING_NOT_REACHABLE);
    /* length of ROUTING_NOT_REACHABLE means not reachable */
    if (length && length >= ROUTING_NOT_REACHABLE)
        return;
 
    /* assemble dvec-encoded move data */
    pos3_t pos;
    VectorCopy(to, pos);
 
    dvec_t dvtab[MAX_ROUTE];
    byte numdv = G_FillDirectionTable(dvtab, lengthof(dvtab), crouchingState, pos);
 
    /* make sure to end any other pending events - we rely on EV_ACTOR_MOVE not being active anymore */
    G_EventEnd();
 
    /* everything ok, found valid route? */
    if (VectorCompare(pos, actor->pos)) {
        /* no floor inventory at this point */
        actor->resetFloor();
 
        if (!G_IsCivilian(actor))
            G_EventMoveCameraTo(G_VisToPM(actor->visflags & ~G_TeamToVisMask(actor->getTeam())), actor->pos);
 
        actor->moveinfo.steps = 0;
        G_ReactionFireNotifyClientStartMove(actor);
        const int initTU = actor->TU;
        int usedTUs = 0;
        const int movingModifier = G_ActorGetInjuryPenalty(actor, MODIFIER_MOVEMENT);
        while (numdv > 0) {
            const int step = actor->moveinfo.steps;
            const byte oldDir = actor->dir;
 
            /* get next dvec */
            numdv--;
            const int dvec = dvtab[numdv];
            /* This is the direction to make the step into */
            const int dir = getDVdir(dvec);
 
            /* turn around first */
            int status = G_ActorDoTurn(actor, dir);
            if ((status & VIS_STOP) && visTeam != 0) {
                autoCrouchRequired = false;
                if (step == 0) {
                    usedTUs += TU_TURN;
                }
                break;
            }
 
            if (visTeam != 0 && G_ActorShouldStopInMidMove(actor, status, dvtab, numdv)) {
                /* don't autocrouch if new enemy becomes visible */
                autoCrouchRequired = false;
                /* if something appears on our route that didn't trigger a VIS_STOP, we have to
                 * send the turn event if this is our first step */
                if (oldDir != actor->dir && step == 0) {
                    G_EventActorTurn(*actor);
                    usedTUs += TU_TURN;
                }
                break;
            }
 
            /* decrease TUs */
            const float div = gi.GetTUsForDirection(dir, actor->isCrouched());
            const int stepTUs = div + movingModifier;
            if (usedTUs + stepTUs > actor->TU)
                break;
            usedTUs += stepTUs;
 
            /* This is now a flag to indicate a change in crouching - we need this for
             * the stop in mid move call(s), because we need the updated entity position */
            int crouchFlag = 0;
            /* Calculate the new position after the decrease in TUs, otherwise the game
             * remembers the false position if the time runs out */
            PosAddDV(actor->pos, crouchFlag, dvec);
 
            /* slower if crouched */
            if (actor->isCrouched())
                actor->speed = ACTOR_SPEED_CROUCHED;
            else
                actor->speed = ACTOR_SPEED_NORMAL;
            actor->speed *= g_actorspeed->value;
 
            const int oldState = actor->state;
            const int oldHP = actor->HP;
            const int oldSTUN = actor->getStun();
            if (crouchFlag == 0) { /* No change in crouch */
                actor->calcOrigin();
 
                /* link it at new position - this must be done for every edict
                 * movement - to let the server know about it. */
                gi.LinkEdict(actor);
 
                /* Only the PHALANX team has these stats right now. */
                if (actor->chr.scoreMission) {
                    const float truediv = gi.GetTUsForDirection(dir, 0);        /* regardless of crouching ! */
                    if (actor->isCrouched())
                        actor->chr.scoreMission->movedCrouched += truediv;
                    else
                        actor->chr.scoreMission->movedNormal += truediv;
                }
                /* write the step to the net */
                const int contentFlags = G_ActorGetContentFlags(actor->origin);
                G_WriteStep(actor, dvec, contentFlags);
 
                status = 0;
 
                /* Set actor->TU because the reaction code relies on actor->TU being accurate. */
                G_ActorSetTU(actor, initTU - usedTUs);
 
                Edict* clientAction = actor->clientAction;
                /* check triggers at new position */
                if (G_TouchTriggers(actor)) {
                    if (!clientAction)
                        status |= VIS_STOP;
                }
 
                /* check if player appears/perishes, seen from other teams */
                G_CheckVis(actor);
 
                /* check for anything appearing, seen by "the moving one" */
                status |= G_CheckVisTeamAll(actor->getTeam(), 0, actor);
 
                G_TouchSolids(actor, 10.0f);
 
                /* state has changed - maybe we walked on a trigger_hurt */
                if (oldState != actor->state || oldHP != actor->HP || oldSTUN != actor->getStun())
                    status |= VIS_STOP;
            } else if (crouchFlag == 1) {
                /* Actor is standing */
                G_ClientStateChange(player, actor, STATE_CROUCHED, true);
            } else if (crouchFlag == -1) {
                /* Actor is crouching and should stand up */
                G_ClientStateChange(player, actor, STATE_CROUCHED, false);
            }
 
            /* check for reaction fire */
            if (G_ReactionFireOnMovement(actor, step)) {
                status |= VIS_STOP;
 
                autoCrouchRequired = false;
            }
 
            /* check for death */
            if (oldHP != actor->HP || oldSTUN != actor->getStun() || oldState != actor->state) {
                /* maybe this was due to rf - then the G_ActorDie was already called */
                if (!actor->isDead()) {
                    G_CheckDeathOrKnockout(actor, nullptr, nullptr, (oldHP - actor->HP) + (actor->getStun() - oldSTUN));
                }
                G_MatchEndCheck();
                autoCrouchRequired = false;
                break;
            }
 
            if (visTeam != 0 && G_ActorShouldStopInMidMove(actor, status, dvtab, numdv - 1)) {
                /* don't autocrouch if new enemy becomes visible */
                autoCrouchRequired = false;
                break;
            }
 
            /* Restore actor->TU because the movement code relies on it not being modified! */
            G_ActorSetTU(actor, initTU);
        }
 
        /* submit the TUs / round down */
        G_ActorSetTU(actor, initTU - usedTUs);
 
        G_SendStats(*actor);
 
        /* end the move */
        G_GetFloorItems(actor);
        G_EventEnd();
    }
 
    if (autoCrouchRequired) {
        /* toggle back to crouched state */
        G_ClientStateChange(player, actor, STATE_CROUCHED, true);
    }
 
    G_ReactionFireNotifyClientEndMove(actor);
}