From 3f639b4f8a74c31372b277cd88783d42d01e72aa Mon Sep 17 00:00:00 2001
From: Sally Cochenour <tehrealsalt@gmail.com>
Date: Tue, 7 Apr 2020 00:40:44 -0400
Subject: [PATCH] Rubberbanding!

---
 src/k_bot.c  | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 src/k_bot.h  |  1 +
 src/k_kart.c | 25 +++++++++++++++++++------
 3 files changed, 70 insertions(+), 6 deletions(-)

diff --git a/src/k_bot.c b/src/k_bot.c
index 5dbe6ea13..c882bc3e2 100644
--- a/src/k_bot.c
+++ b/src/k_bot.c
@@ -100,6 +100,56 @@ boolean K_BotCanTakeCut(player_t *player)
 	return false;
 }
 
+fixed_t K_BotRubberband(player_t *player)
+{
+	fixed_t rubberband = FRACUNIT;
+	player_t *besthumanplayer = NULL;
+	UINT8 i;
+
+	for (i = 0; i < MAXPLAYERS; i++)
+	{
+		if (!playeringame[i] || players[i].spectator || players[i].exiting)
+		{
+			continue;
+		}
+
+		if (&players[i] == player || players[i].bot)
+		{
+			continue;
+		}
+
+		if (besthumanplayer == NULL || players[i].distancetofinish < besthumanplayer->distancetofinish)
+		{
+			besthumanplayer = &players[i];
+		}
+	}
+
+	if (besthumanplayer != NULL)
+	{
+		UINT32 wanteddist = besthumanplayer->distancetofinish; // TODO: Add difficulty here
+
+		if (wanteddist > player->distancetofinish)
+		{
+			rubberband = FRACUNIT + (2 * (player->distancetofinish - wanteddist));
+		}
+		else
+		{
+			rubberband = FRACUNIT + (8 * (player->distancetofinish - wanteddist));
+		}
+	}
+
+	if (rubberband > 2*FRACUNIT)
+	{
+		rubberband = 2*FRACUNIT;
+	}
+	else if (rubberband < 2*FRACUNIT/3)
+	{
+		rubberband = 2*FRACUNIT/3;
+	}
+
+	return rubberband;
+}
+
 static fixed_t K_DistanceOfLineFromPoint(fixed_t v1x, fixed_t v1y, fixed_t v2x, fixed_t v2y, fixed_t cx, fixed_t cy)
 {
 	fixed_t v1toc[2] = {cx - v1x, cy - v1y};
diff --git a/src/k_bot.h b/src/k_bot.h
index 797843dea..38e3af27b 100644
--- a/src/k_bot.h
+++ b/src/k_bot.h
@@ -22,4 +22,5 @@ typedef struct botprediction_s {
 void K_AddBots(SINT8 numbots);
 boolean K_PlayerUsesBotMovement(player_t *player);
 boolean K_BotCanTakeCut(player_t *player);
+fixed_t K_BotRubberband(player_t *player);
 void K_BuildBotTiccmd(player_t *player, ticcmd_t *cmd);
diff --git a/src/k_kart.c b/src/k_kart.c
index f2f979387..ee0b9d95c 100644
--- a/src/k_kart.c
+++ b/src/k_kart.c
@@ -2693,13 +2693,11 @@ fixed_t K_GetKartSpeed(player_t *player, boolean doboostpower)
 
 	if (K_PlayerUsesBotMovement(player))
 	{
-		fixed_t speedmul = FRACUNIT;
+		fixed_t speedmul = K_BotRubberband(player);
 
 		// Give top speed a buff for bots, since it's a fairly weak stat without drifting
 		speedmul += ((kartspeed-1) * FRACUNIT / 8) / 10; // +10% for speed 9
 
-		// TODO: Rubberbanding goes here. Do it for accel too!
-
 		finalspeed = FixedMul(finalspeed, speedmul);
 	}
 
@@ -2722,6 +2720,11 @@ fixed_t K_GetKartAccel(player_t *player)
 	//k_accel += 3 * (9 - kartspeed); // 36 - 60
 	k_accel += 4 * (9 - kartspeed); // 32 - 64
 
+	if (K_PlayerUsesBotMovement(player))
+	{
+		k_accel = FixedMul(k_accel, K_BotRubberband(player));
+	}
+
 	return FixedMul(k_accel, FRACUNIT+player->kartstuff[k_accelboost]);
 }
 
@@ -6474,6 +6477,13 @@ static waypoint_t *K_GetPlayerNextWaypoint(player_t *player)
 				angle_t nextbestmomdelta = momdelta;
 				size_t i = 0U;
 
+				if (K_PlayerUsesBotMovement(player))
+				{
+					// Try to force bots to use a next waypoint
+					nextbestdelta = ANGLE_MAX;
+					nextbestmomdelta = ANGLE_MAX;
+				}
+
 				if ((waypoint->nextwaypoints != NULL) && (waypoint->numnextwaypoints > 0U))
 				{
 					for (i = 0U; i < waypoint->numnextwaypoints; i++)
@@ -6806,6 +6816,12 @@ INT16 K_GetKartTurnValue(player_t *player, INT16 turnvalue)
 	if (player->spectator)
 		return turnvalue;
 
+	if (K_PlayerUsesBotMovement(player))
+	{
+		turnvalue = FixedMul(turnvalue, (5*FRACUNIT)/4); // Base increase to turning
+		turnvalue = FixedMul(turnvalue, K_BotRubberband(player));
+	}
+
 	if (player->kartstuff[k_drift] != 0 && P_IsObjectOnGround(player->mo))
 	{
 		// If we're drifting we have a completely different turning value
@@ -6826,9 +6842,6 @@ INT16 K_GetKartTurnValue(player_t *player, INT16 turnvalue)
 	if (EITHERSNEAKER(player) || player->kartstuff[k_invincibilitytimer] || player->kartstuff[k_growshrinktimer] > 0)
 		turnvalue = FixedMul(turnvalue, (5*FRACUNIT)/4);
 
-	if (K_PlayerUsesBotMovement(player))
-		turnvalue = FixedMul(turnvalue, (5*FRACUNIT)/4);
-
 	return turnvalue;
 }