sv_snapshot.c

quakeIII源码这个不用我多说吧

/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.

This file is part of Quake III Arena source code.

Quake III Arena source code 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.

Quake III Arena source code 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 Foobar; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/

#include "server.h"


/*
=============================================================================

Delta encode a client frame onto the network channel

A normal server packet will look like:

4	sequence number (high bit set if an oversize fragment)
<optional reliable commands>
1	svc_snapshot
4	last client reliable command
4	serverTime
1	lastframe for delta compression
1	snapFlags
1	areaBytes
<areabytes>
<playerstate>
<packetentities>

=============================================================================
*/

/*
=============
SV_EmitPacketEntities

Writes a delta update of an entityState_t list to the message.
=============
*/
static void SV_EmitPacketEntities( clientSnapshot_t *from, clientSnapshot_t *to, msg_t *msg ) {
	entityState_t	*oldent, *newent;
	int		oldindex, newindex;
	int		oldnum, newnum;
	int		from_num_entities;

	// generate the delta update
	if ( !from ) {
		from_num_entities = 0;
	} else {
		from_num_entities = from->num_entities;
	}

	newent = NULL;
	oldent = NULL;
	newindex = 0;
	oldindex = 0;
	while ( newindex < to->num_entities || oldindex < from_num_entities ) {
		if ( newindex >= to->num_entities ) {
			newnum = 9999;
		} else {
			newent = &svs.snapshotEntities[(to->first_entity+newindex) % svs.numSnapshotEntities];
			newnum = newent->number;
		}

		if ( oldindex >= from_num_entities ) {
			oldnum = 9999;
		} else {
			oldent = &svs.snapshotEntities[(from->first_entity+oldindex) % svs.numSnapshotEntities];
			oldnum = oldent->number;
		}

		if ( newnum == oldnum ) {
			// delta update from old position
			// because the force parm is qfalse, this will not result
			// in any bytes being emited if the entity has not changed at all
			MSG_WriteDeltaEntity (msg, oldent, newent, qfalse );
			oldindex++;
			newindex++;
			continue;
		}

		if ( newnum < oldnum ) {
			// this is a new entity, send it from the baseline
			MSG_WriteDeltaEntity (msg, &sv.svEntities[newnum].baseline, newent, qtrue );
			newindex++;
			continue;
		}

		if ( newnum > oldnum ) {
			// the old entity isn't present in the new message
			MSG_WriteDeltaEntity (msg, oldent, NULL, qtrue );
			oldindex++;
			continue;
		}
	}

	MSG_WriteBits( msg, (MAX_GENTITIES-1), GENTITYNUM_BITS );	// end of packetentities
}



/*
==================
SV_WriteSnapshotToClient
==================
*/
static void SV_WriteSnapshotToClient( client_t *client, msg_t *msg ) {
	clientSnapshot_t	*frame, *oldframe;
	int					lastframe;
	int					i;
	int					snapFlags;

	// this is the snapshot we are creating
	frame = &client->frames[ client->netchan.outgoingSequence & PACKET_MASK ];

	// try to use a previous frame as the source for delta compressing the snapshot
	if ( client->deltaMessage <= 0 || client->state != CS_ACTIVE ) {
		// client is asking for a retransmit
		oldframe = NULL;
		lastframe = 0;
	} else if ( client->netchan.outgoingSequence - client->deltaMessage 
		>= (PACKET_BACKUP - 3) ) {
		// client hasn't gotten a good message through in a long time
		Com_DPrintf ("%s: Delta request from out of date packet.\n", client->name);
		oldframe = NULL;
		lastframe = 0;
	} else {
		// we have a valid snapshot to delta from
		oldframe = &client->frames[ client->deltaMessage & PACKET_MASK ];
		lastframe = client->netchan.outgoingSequence - client->deltaMessage;

		// the snapshot's entities may still have rolled off the buffer, though
		if ( oldframe->first_entity <= svs.nextSnapshotEntities - svs.numSnapshotEntities ) {
			Com_DPrintf ("%s: Delta request from out of date entities.\n", client->name);
			oldframe = NULL;
			lastframe = 0;
		}
	}

	MSG_WriteByte (msg, svc_snapshot);

	// NOTE, MRE: now sent at the start of every message from server to client
	// let the client know which reliable clientCommands we have received
	//MSG_WriteLong( msg, client->lastClientCommand );

	// send over the current server time so the client can drift
	// its view of time to try to match
	MSG_WriteLong (msg, svs.time);

	// what we are delta'ing from
	MSG_WriteByte (msg, lastframe);

	snapFlags = svs.snapFlagServerBit;
	if ( client->rateDelayed ) {
		snapFlags |= SNAPFLAG_RATE_DELAYED;
	}
	if ( client->state != CS_ACTIVE ) {
		snapFlags |= SNAPFLAG_NOT_ACTIVE;
	}

	MSG_WriteByte (msg, snapFlags);

	// send over the areabits
	MSG_WriteByte (msg, frame->areabytes);
	MSG_WriteData (msg, frame->areabits, frame->areabytes);

	// delta encode the playerstate
	if ( oldframe ) {
		MSG_WriteDeltaPlayerstate( msg, &oldframe->ps, &frame->ps );
	} else {
		MSG_WriteDeltaPlayerstate( msg, NULL, &frame->ps );
	}

	// delta encode the entities
	SV_EmitPacketEntities (oldframe, frame, msg);

	// padding for rate debugging
	if ( sv_padPackets->integer ) {
		for ( i = 0 ; i < sv_padPackets->integer ; i++ ) {
			MSG_WriteByte (msg, svc_nop);
		}
	}
}


/*
==================
SV_UpdateServerCommandsToClient

(re)send all server commands the client hasn't acknowledged yet
==================
*/
void SV_UpdateServerCommandsToClient( client_t *client, msg_t *msg ) {
	int		i;

	// write any unacknowledged serverCommands
	for ( i = client->reliableAcknowledge + 1 ; i <= client->reliableSequence ; i++ ) {
		MSG_WriteByte( msg, svc_serverCommand );
		MSG_WriteLong( msg, i );
		MSG_WriteString( msg, client->reliableCommands[ i & (MAX_RELIABLE_COMMANDS-1) ] );
	}
	client->reliableSent = client->reliableSequence;
}

/*
=============================================================================

Build a client snapshot structure

=============================================================================
*/

#define	MAX_SNAPSHOT_ENTITIES	1024
typedef struct {
	int		numSnapshotEntities;
	int		snapshotEntities[MAX_SNAPSHOT_ENTITIES];	
} snapshotEntityNumbers_t;

/*
=======================
SV_QsortEntityNumbers
=======================
*/
static int QDECL SV_QsortEntityNumbers( const void *a, const void *b ) {
	int	*ea, *eb;

	ea = (int *)a;
	eb = (int *)b;

	if ( *ea == *eb ) {
		Com_Error( ERR_DROP, "SV_QsortEntityStates: duplicated entity" );
	}

	if ( *ea < *eb ) {
		return -1;
	}

	return 1;
}


/*
===============
SV_AddEntToSnapshot
===============
*/
static void SV_AddEntToSnapshot( svEntity_t *svEnt, sharedEntity_t *gEnt, snapshotEntityNumbers_t *eNums ) {
	// if we have already added this entity to this snapshot, don't add again
	if ( svEnt->snapshotCounter == sv.snapshotCounter ) {
		return;
	}
	svEnt->snapshotCounter = sv.snapshotCounter;

	// if we are full, silently discard entities
	if ( eNums->numSnapshotEntities == MAX_SNAPSHOT_ENTITIES ) {
		return;
	}

	eNums->snapshotEntities[ eNums->numSnapshotEntities ] = gEnt->s.number;
	eNums->numSnapshotEntities++;
}

/*
===============
SV_AddEntitiesVisibleFromPoint
===============
*/
static void SV_AddEntitiesVisibleFromPoint( vec3_t origin, clientSnapshot_t *frame, 
									snapshotEntityNumbers_t *eNums, qboolean portal ) {
	int		e, i;
	sharedEntity_t *ent;
	svEntity_t	*svEnt;
	int		l;
	int		clientarea, clientcluster;
	int		leafnum;
	int		c_fullsend;
	byte	*clientpvs;
	byte	*bitvector;

	// during an error shutdown message we may need to transmit
	// the shutdown message after the server has shutdown, so
	// specfically check for it
	if ( !sv.state ) {
		return;
	}

	leafnum = CM_PointLeafnum (origin);
	clientarea = CM_LeafArea (leafnum);
	clientcluster = CM_LeafCluster (leafnum);

	// calculate the visible areas
	frame->areabytes = CM_WriteAreaBits( frame->areabits, clientarea );

	clientpvs = CM_ClusterPVS (clientcluster);

	c_fullsend = 0;

	for ( e = 0 ; e < sv.num_entities ; e++ ) {
		ent = SV_GentityNum(e);

		// never send entities that aren't linked in
		if ( !ent->r.linked ) {
			continue;
		}

		if (ent->s.number != e) {
			Com_DPrintf ("FIXING ENT->S.NUMBER!!!\n");
			ent->s.number = e;
		}

		// entities can be flagged to explicitly not be sent to the client
		if ( ent->r.svFlags & SVF_NOCLIENT ) {
			continue;
		}

		// entities can be flagged to be sent to only one client
		if ( ent->r.svFlags & SVF_SINGLECLIENT ) {
			if ( ent->r.singleClient != frame->ps.clientNum ) {
				continue;
			}
		}
		// entities can be flagged to be sent to everyone but one client
		if ( ent->r.svFlags & SVF_NOTSINGLECLIENT ) {
			if ( ent->r.singleClient == frame->ps.clientNum ) {
				continue;
			}
		}