From e34ec94721d3d9e57333fd7f49f8b9e153e1088e Mon Sep 17 00:00:00 2001
From: Sally Coolatta <tehrealsalt@gmail.com>
Date: Tue, 27 Sep 2022 18:14:44 -0400
Subject: [PATCH] Smoothly adjust underwater turn nerf

The actual issue was that turning was nerfed by a flat x0.5 when strafing was enabled, but the strafe amount was speed based. This meant that you got way less turning at low speed, and no strafe to make up for it.
---
 src/k_kart.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/k_kart.c b/src/k_kart.c
index 43e14fbdd..bf7200b8a 100644
--- a/src/k_kart.c
+++ b/src/k_kart.c
@@ -8974,6 +8974,16 @@ INT16 K_UpdateSteeringValue(INT16 inputSteering, INT16 destSteering)
 	return outputSteering;
 }
 
+static fixed_t K_GetUnderwaterStrafeMul(player_t *player)
+{
+	const fixed_t minSpeed = 11 * player->mo->scale;
+	fixed_t baseline = INT32_MAX;
+
+	baseline = 2 * K_GetKartSpeed(player, false, true) / 3;
+
+	return max(0, FixedDiv(player->speed - minSpeed, baseline - minSpeed));
+}
+
 INT16 K_GetKartTurnValue(player_t *player, INT16 turnvalue)
 {
 	fixed_t turnfixed = turnvalue * FRACUNIT;
@@ -9051,10 +9061,10 @@ INT16 K_GetKartTurnValue(player_t *player, INT16 turnvalue)
 		turnfixed = FixedMul(turnfixed, FRACUNIT + player->handleboost);
 	}
 
-	if ((player->mo->eflags & MFE_UNDERWATER) &&
-			player->speed > 11 * player->mo->scale)
+	if (player->mo->eflags & MFE_UNDERWATER)
 	{
-		turnfixed /= 2;
+		fixed_t div = min(FRACUNIT + K_GetUnderwaterStrafeMul(player), 2*FRACUNIT);
+		turnfixed = FixedDiv(turnfixed, div);
 	}
 
 	// Weight has a small effect on turning
@@ -9065,18 +9075,15 @@ INT16 K_GetKartTurnValue(player_t *player, INT16 turnvalue)
 
 INT32 K_GetUnderwaterTurnAdjust(player_t *player)
 {
-	if ((player->mo->eflags & MFE_UNDERWATER) &&
-			player->speed > 11 * player->mo->scale)
+	if (player->mo->eflags & MFE_UNDERWATER)
 	{
 		INT32 steer = (K_GetKartTurnValue(player,
 					player->steering) << TICCMD_REDUCE);
-		fixed_t minimum = INT32_MAX;
 
 		if (!player->drift)
 			steer = 9 * steer / 5;
 
-		minimum = 2 * K_GetKartSpeed(player, false, true) / 3;
-		return FixedMul(steer, 8 * FixedDiv(max(player->speed, minimum), minimum));
+		return FixedMul(steer, 8 * K_GetUnderwaterStrafeMul(player));
 	}
 	else
 		return 0;