Initial commit

rerelease/p_trail.cpp

@@ -0,0 +1,153 @@
+// Copyright (c) ZeniMax Media Inc.
+// Licensed under the GNU General Public License 2.0.
+#include "g_local.h"
+
+/*
+==============================================================================
+
+PLAYER TRAIL
+
+==============================================================================
+
+This is a two-way list containing the a list of points of where
+the player has been recently. It is used by monsters for pursuit.
+
+This is improved from vanilla; now, the list itself is stored in
+client data so it can be stored for multiple clients.
+
+chain = next
+enemy = prev
+
+The head node will always have a null "chain", the tail node
+will always have a null "enemy".
+*/
+
+constexpr size_t TRAIL_LENGTH = 8;
+
+// places a new entity at the head of the player trail.
+// the tail entity may be moved to the front if the length
+// is at the end.
+static edict_t *PlayerTrail_Spawn(edict_t *owner)
+{
+	size_t len = 0;
+
+	for (edict_t *tail = owner->client->trail_tail; tail; tail = tail->chain)
+		len++;
+
+	edict_t *trail;
+
+	// move the tail to the head
+	if (len == TRAIL_LENGTH)
+	{
+		// unlink the old tail
+		trail = owner->client->trail_tail;
+		owner->client->trail_tail = trail->chain;
+		owner->client->trail_tail->enemy = nullptr;
+		trail->chain = trail->enemy = nullptr;
+	}
+	else
+	{
+		// spawn a new head
+		trail = G_Spawn();
+		trail->classname = "player_trail";
+	}
+
+	// link as new head
+	if (owner->client->trail_head)
+		owner->client->trail_head->chain = trail;
+	trail->enemy = owner->client->trail_head;
+	owner->client->trail_head = trail;
+
+	// if there's no tail, we become the tail too
+	if (!owner->client->trail_tail)
+		owner->client->trail_tail = trail;
+
+	return trail;
+}
+
+// destroys all player trail entities in the map.
+// we don't want these to stay around across level loads.
+void PlayerTrail_Destroy(edict_t *player)
+{
+	for (size_t i = 0; i < globals.num_edicts; i++)
+		if (g_edicts[i].classname && strcmp(g_edicts[i].classname, "player_trail") == 0)
+			if (!player || g_edicts[i].owner == player)
+				G_FreeEdict(&g_edicts[i]);
+
+	if (player)
+		player->client->trail_head = player->client->trail_tail = nullptr;
+	else for (size_t i = 0; i < game.maxclients; i++)
+		game.clients[i].trail_head = game.clients[i].trail_tail = nullptr;
+}
+
+// check to see if we can add a new player trail spot
+// for this player.
+void PlayerTrail_Add(edict_t *player)
+{
+	// if we can still see the head, we don't want a new one.
+	if (player->client->trail_head && visible(player, player->client->trail_head))
+		return;
+	// don't spawn trails in intermission, if we're dead, if we're noclipping or not on ground yet
+	else if (level.intermissiontime || player->health <= 0 || player->movetype == MOVETYPE_NOCLIP ||
+		!player->groundentity)
+		return;
+
+	edict_t *trail = PlayerTrail_Spawn(player);
+	trail->s.origin = player->s.old_origin;
+	trail->timestamp = level.time;
+	trail->owner = player;
+}
+
+// pick a trail node that matches the player
+// we're hunting that is visible to us.
+edict_t *PlayerTrail_Pick(edict_t *self, bool next)
+{
+	// not player or doesn't have a trail yet
+	if (!self->enemy->client || !self->enemy->client->trail_head)
+		return nullptr;
+
+	// find which marker head that was dropped while we
+	// were searching for this enemy
+	edict_t *marker;
+
+	for (marker = self->enemy->client->trail_head; marker; marker = marker->enemy)
+	{
+		if (marker->timestamp <= self->monsterinfo.trail_time)
+			continue;
+
+		break;
+	}
+
+	if (next)
+	{
+		// find the marker we're closest to
+		float closest_dist = std::numeric_limits<float>::infinity();
+		edict_t *closest = nullptr;
+
+		for (edict_t *m2 = marker; m2; m2 = m2->enemy)
+		{
+			float len = (m2->s.origin - self->s.origin).lengthSquared();
+
+			if (len < closest_dist)
+			{
+				closest_dist = len;
+				closest = m2;
+			}
+		}
+
+		// should never happen
+		if (!closest)
+			return nullptr;
+
+		// use the next one from the closest one
+		marker = closest->chain;
+	}
+	else
+	{
+		// from that marker, find the first one we can see
+		for (; marker && !visible(self, marker); marker = marker->enemy)
+			continue;
+	}
+
+	return marker;
+}