Bots: Decide what item they want without using RNG

Makes Lv.1 a lot less aggressive, and Lv.MAX slightly more aggressive. But the main advantage is simply that they are deterministic again and I can  :D

src/d_player.h

@@ -333,6 +333,9 @@ struct botvars_t
 
 	tic_t spindashconfirm; // When high enough, they will try spindashing
 	UINT32 respawnconfirm; // When high enough, they will use Ring Shooter
+
+	UINT8 roulettePriority; // What items to go for on the roulette
+	tic_t rouletteTimeout; // If it takes too long to decide, try lowering priority until we find something valid.
 };
 
 // player_t struct for round-specific condition tracking
@@ -399,6 +402,23 @@ struct itemroulette_t
 	boolean eggman;
 };
 
+// enum for bot item priorities
+typedef enum
+{
+	BOT_ITEM_PR__FALLBACK, // Priority decrement fallback -- end the bot's roulette asap
+	BOT_ITEM_PR_NEUTRAL, // Default priority
+	BOT_ITEM_PR_FRONTRUNNER,
+	BOT_ITEM_PR_SPEED,
+	// Priorities beyond this point are explicitly
+	// used when any item from their priority group
+	// exists in the roulette at all.
+	BOT_ITEM_PR__OVERRIDES,
+	BOT_ITEM_PR_RINGDEBT = BOT_ITEM_PR__OVERRIDES,
+	BOT_ITEM_PR_POWER,
+	BOT_ITEM_PR_SPB,
+	BOT_ITEM_PR__MAX
+} botItemPriority_e;
+
 // player_t struct for loop state
 typedef struct {
 	fixed_t radius;

src/k_bot.h

@@ -37,6 +37,9 @@ extern "C" {
 // How many tics without being able to make progress before we'll let you respawn.
 #define BOTRESPAWNCONFIRM (5*TICRATE)
 
+// How long it takes for a Lv.1 bot to decide to pick an item.
+#define BOT_ITEM_DECISION_TIME (3*TICRATE)
+
 // Point for bots to aim for
 struct botprediction_t {
 	fixed_t x, y;
@@ -277,6 +280,25 @@ void K_UpdateBotGameplayVars(player_t *player);
 
 void K_BotItemUsage(player_t *player, ticcmd_t *cmd, INT16 turnamt);
 
+
+/*--------------------------------------------------
+	void K_BotPickItemPriority(player_t *player)
+
+		Sets a bot's desired item classification
+		based on what they're ,
+		and delays based on their difficulty
+		intended to be run when starting a roulette.
+
+	Input Arguments:-
+		player - Bot to set the item classification for.
+
+	Return:-
+		N/A
+--------------------------------------------------*/
+
+void K_BotPickItemPriority(player_t *player);
+
+
 #ifdef __cplusplus
 } // extern "C"
 #endif

src/k_botitem.c

@@ -1394,15 +1394,54 @@ static void K_BotItemRings(player_t *player, ticcmd_t *cmd)
 --------------------------------------------------*/
 static void K_BotItemRouletteMash(player_t *player, ticcmd_t *cmd)
 {
+	// 12 tics late for Lv.1, frame-perfect for Lv.MAX
+	const tic_t confirmTime = (MAXBOTDIFFICULTY - player->botvars.difficulty);
+
 	if (K_ItemButtonWasDown(player) == true)
 	{
 		return;
 	}
 
-	// TODO: Would be nice to implement smarter behavior
-	// for selecting items.
+	if (player->botvars.roulettePriority == BOT_ITEM_PR__FALLBACK)
+	{
+		// No items were part of our list, so set immediately.
+		player->botvars.itemconfirm = confirmTime + 1;
+	}
+	else if (player->botvars.itemconfirm > 0)
+	{
+		// Delaying our reaction time a bit...
+		player->botvars.itemconfirm++;
+	}
+	else
+	{
+		botItemPriority_e currentPriority = K_GetBotItemPriority(
+			player->itemRoulette.itemList[ player->itemRoulette.index ]
+		);
 
-	cmd->buttons |= BT_ATTACK;
+		if (player->botvars.roulettePriority == currentPriority) 
+		{
+			// This is the item we want! Start timing!
+			player->botvars.itemconfirm++;
+		}
+		else
+		{
+			// Not the time we want... if we take too long,
+			// reduce priority until we get to a valid one.
+			player->botvars.rouletteTimeout++;
+
+			if (player->botvars.rouletteTimeout > player->itemRoulette.itemListLen * player->itemRoulette.speed)
+			{
+				player->botvars.roulettePriority--;
+				player->botvars.rouletteTimeout = 0;
+			}
+		}
+	}
+
+	if (player->botvars.itemconfirm > confirmTime)
+	{
+		// We've waited out our reaction time -- press the button now!
+		cmd->buttons |= BT_ATTACK;
+	}
 }
 
 /*--------------------------------------------------
@@ -1568,3 +1607,92 @@ void K_BotItemUsage(player_t *player, ticcmd_t *cmd, INT16 turnamt)
 		}
 	}
 }
+
+/*--------------------------------------------------
+	void K_BotPickItemPriority(player_t *player)
+
+		See header file for description.
+--------------------------------------------------*/
+void K_BotPickItemPriority(player_t *player)
+{
+	const fixed_t closeDistance = FixedMul(1280 * mapobjectscale, K_GetKartGameSpeedScalar(gamespeed));
+	size_t i;
+
+	// Roulette reaction time. This is how long to wait before considering items.
+	// Takes 3 seconds for Lv.1, is instant for Lv.MAX
+	player->botvars.itemdelay = ((MAXBOTDIFFICULTY - player->botvars.difficulty) * BOT_ITEM_DECISION_TIME) / (MAXBOTDIFFICULTY - 1);
+	player->botvars.itemconfirm = 0;
+
+	// Set neutral items by default.
+	player->botvars.roulettePriority = BOT_ITEM_PR_NEUTRAL;
+	player->botvars.rouletteTimeout = 0;
+
+	// Check for items that are extremely high priority.
+	for (i = 0; i < player->itemRoulette.itemListLen; i++)
+	{
+		botItemPriority_e priority = K_GetBotItemPriority( player->itemRoulette.itemList[i] );
+
+		if (priority < BOT_ITEM_PR__OVERRIDES)
+		{
+			// Not high enough to override.
+			continue;
+		}
+
+		player->botvars.roulettePriority = max( player->botvars.roulettePriority, priority );
+	}
+
+	if (player->botvars.roulettePriority >= BOT_ITEM_PR__OVERRIDES)
+	{
+		// Selected a priority in the loop above.
+		return;
+	}
+
+	for (i = 0; i < MAXPLAYERS; i++)
+	{
+		player_t *other = NULL;
+		fixed_t distance = INT32_MAX;
+
+		if (playeringame[i] == false)
+		{
+			continue;
+		}
+
+		other = &players[i];
+		if (other->spectator == true || P_MobjWasRemoved(other->mo) == true)
+		{
+			continue;
+		}
+
+		distance = P_AproxDistance(
+			P_AproxDistance(
+				other->mo->x - player->mo->x,
+				other->mo->y - player->mo->y
+			),
+			other->mo->z - player->mo->z
+		);
+
+		if (distance < closeDistance)
+		{
+			// A player is relatively close.
+			break;
+		}
+	}
+
+	if (i == MAXPLAYERS)
+	{
+		// Players are nearby, stay as neutral priority.
+		return;
+	}
+
+	// Players are far away enough to give you breathing room.
+	if (player->position == 1)
+	{
+		// Frontrunning, so pick frontrunner items!
+		player->botvars.roulettePriority = BOT_ITEM_PR_FRONTRUNNER;
+	}
+	else
+	{
+		// Behind, so pick speed items!
+		player->botvars.roulettePriority = BOT_ITEM_PR_SPEED;
+	}
+}

src/k_roulette.c

@@ -262,6 +262,71 @@ boolean K_ItemSingularity(kartitems_t item)
 	}
 }
 
+/*--------------------------------------------------
+	botItemPriority_e K_GetBotItemPriority(kartitems_t type)
+
+		See header file for description.
+--------------------------------------------------*/
+botItemPriority_e K_GetBotItemPriority(kartitems_t type)
+{
+	switch (type)
+	{
+		case KITEM_SPB:
+		{
+			// Items that are intended to improve the game balance for everyone.
+			return BOT_ITEM_PR_SPB;
+		}
+		case KITEM_INVINCIBILITY:
+		case KITEM_GROW:
+		case KITEM_SHRINK:
+		case KITEM_LIGHTNINGSHIELD:
+		case KITEM_BUBBLESHIELD:
+		case KITEM_FLAMESHIELD:
+		{
+			// Items that drastically improve your own defense and/or speed.
+			return BOT_ITEM_PR_POWER;
+		}
+		case KITEM_SUPERRING:
+		{
+			// Items that get you out of ring debt.
+			return BOT_ITEM_PR_RINGDEBT;
+		}
+		case KITEM_SNEAKER:
+		case KITEM_ROCKETSNEAKER:
+		case KITEM_GARDENTOP:
+		case KITEM_POGOSPRING:
+		{
+			// Used when not in 1st place and relatively far from players.
+			// Items that give you speed with no protection.
+			return BOT_ITEM_PR_SPEED;
+		}
+		case KITEM_HYUDORO:
+		case KITEM_LANDMINE:
+		case KITEM_DROPTARGET:
+		case KITEM_EGGMAN:
+		case KITEM_GACHABOM:
+		{
+			// Used when in 1st place and relatively far from players.
+			// Typically attack items that don't give you protection.
+			return BOT_ITEM_PR_FRONTRUNNER;
+		}
+		case KITEM_ORBINAUT:
+		case KITEM_BALLHOG:
+		case KITEM_JAWZ:
+		case KITEM_BANANA:
+		case KITEM_MINE:
+		{
+			// Used in all other instances (close to other players, no priority override)
+			// Typically attack items that give you protection.
+			return BOT_ITEM_PR_NEUTRAL;
+		}
+		default:
+		{
+			return BOT_ITEM_PR__FALLBACK;
+		}
+	}
+}
+
 /*--------------------------------------------------
 	static fixed_t K_ItemOddsScale(UINT8 playerCount)
 
@@ -1351,9 +1416,10 @@ void K_StartItemRoulette(player_t *const player)
 
 	K_FillItemRouletteData(player, roulette);
 
-	// Make the bots select their item after a little while.
-	// One of the few instances of bot RNG, would be nice to remove it.
-	player->botvars.itemdelay = P_RandomRange(PR_UNDEFINED, TICRATE, TICRATE*3);
+	if (K_PlayerUsesBotMovement(player) == true)
+	{
+		K_BotPickItemPriority(player);
+	}
 
 	// Prevent further duplicates of items that
 	// are intended to only have one out at a time.

src/k_roulette.h

@@ -57,6 +57,23 @@ boolean K_ItemEnabled(kartitems_t item);
 boolean K_ItemSingularity(kartitems_t item);
 
 
+/*--------------------------------------------------
+	botItemPriority_e K_GetBotItemPriority(kartitems_t type)
+
+		Returns an item's priority value, which
+		bots use to determine what kind of item they
+		want when the roulette is started.
+
+	Input Arguments:-
+		item - The item to check.
+
+	Return:-
+		The item's priority type.
+--------------------------------------------------*/
+
+botItemPriority_e K_GetBotItemPriority(kartitems_t type);
+
+
 /*--------------------------------------------------
 	INT32 K_KartGetItemOdds(const player_t *player, itemroulette_t *const roulette, UINT8 pos, kartitems_t item);
 

src/p_saveg.c

@@ -444,6 +444,8 @@ static void P_NetArchivePlayers(savebuffer_t *save)
 		WRITESINT8(save->p, players[i].botvars.turnconfirm);
 		WRITEUINT32(save->p, players[i].botvars.spindashconfirm);
 		WRITEUINT32(save->p, players[i].botvars.respawnconfirm);
+		WRITEUINT8(save->p, players[i].botvars.roulettePriority);
+		WRITEUINT32(save->p, players[i].botvars.rouletteTimeout);
 
 		// itemroulette_t
 		WRITEUINT8(save->p, players[i].itemRoulette.active);
@@ -827,6 +829,8 @@ static void P_NetUnArchivePlayers(savebuffer_t *save)
 		players[i].botvars.turnconfirm = READSINT8(save->p);
 		players[i].botvars.spindashconfirm = READUINT32(save->p);
 		players[i].botvars.respawnconfirm = READUINT32(save->p);
+		players[i].botvars.roulettePriority = READUINT8(save->p);
+		players[i].botvars.rouletteTimeout = READUINT32(save->p);
 
 		// itemroulette_t
 		players[i].itemRoulette.active = (boolean)READUINT8(save->p);