From a63e9fe00247de03fe466cf510cdfc54d62d7de6 Mon Sep 17 00:00:00 2001
From: fickleheart <fickle@tinted.red>
Date: Mon, 10 Feb 2020 00:06:16 -0600
Subject: [PATCH] Improvements to polyobjects carrying things:

- Fixed loss of precision in rotate carry causing objects to slide off
- Adjusted player carrying logic to make platforms less slippery
- Finally obsoleted the player-specific rotate hack now that I found the
  actual problem :]
---
 src/p_polyobj.c | 52 ++++++++++++++++++++++++++++++-------------------
 src/p_user.c    |  4 +++-
 2 files changed, 35 insertions(+), 21 deletions(-)

diff --git a/src/p_polyobj.c b/src/p_polyobj.c
index cd0a44bb4..a206d0171 100644
--- a/src/p_polyobj.c
+++ b/src/p_polyobj.c
@@ -1001,15 +1001,35 @@ static void Polyobj_pushThing(polyobj_t *po, line_t *line, mobj_t *mo)
 //
 static void Polyobj_slideThing(mobj_t *mo, fixed_t dx, fixed_t dy)
 {
-	if (mo->player) { // Do something similar to conveyor movement. -Red
-		mo->player->cmomx += dx;
-		mo->player->cmomy += dy;
+	if (mo->player) { // Finally this doesn't suck eggs -fickle
+		fixed_t cdx, cdy;
 
-		dx = FixedMul(dx, CARRYFACTOR);
-		dy = FixedMul(dy, CARRYFACTOR);
+		cdx = FixedMul(dx, FRACUNIT-CARRYFACTOR);
+		cdy = FixedMul(dy, FRACUNIT-CARRYFACTOR);
 
-		mo->player->cmomx -= dx;
-		mo->player->cmomy -= dy;
+		if (mo->player->onconveyor == 1)
+		{
+			mo->momx += cdx;
+			mo->momy += cdy;
+
+			// Multiple slides in the same tic, somehow
+			mo->player->cmomx += cdx;
+			mo->player->cmomy += cdy;
+		}
+		else
+		{
+			if (mo->player->onconveyor == 3)
+			{
+				mo->momx += cdx - mo->player->cmomx;
+				mo->momy += cdy - mo->player->cmomy;
+			}
+
+			mo->player->cmomx = cdx;
+			mo->player->cmomy = cdy;
+		}
+
+		dx = FixedMul(dx, FRACUNIT - mo->friction);
+		dy = FixedMul(dy, FRACUNIT - mo->friction);
 
 		if (mo->player->pflags & PF_SPINNING && (mo->player->rmomx || mo->player->rmomy) && !(mo->player->pflags & PF_STARTDASH)) {
 #define SPINMULT 5184 // Consider this a substitute for properly calculating FRACUNIT-friction. I'm tired. -Red
@@ -1282,7 +1302,8 @@ static void Polyobj_rotateThings(polyobj_t *po, vertex_t origin, angle_t delta,
 {
 	static INT32 pomovecount = 10000;
 	INT32 x, y;
-	angle_t deltafine = delta >> ANGLETOFINESHIFT;
+	angle_t deltafine = (((po->angle + delta) >> ANGLETOFINESHIFT) - (po->angle >> ANGLETOFINESHIFT)) & FINEMASK;
+	// This fineshift trickery replaces the old delta>>ANGLETOFINESHIFT; doing it this way avoids loss of precision causing objects to slide off -fickle
 
 	pomovecount++;
 
@@ -1334,19 +1355,10 @@ static void Polyobj_rotateThings(polyobj_t *po, vertex_t origin, angle_t delta,
 					oldxoff = mo->x-origin.x;
 					oldyoff = mo->y-origin.y;
 
-					if (mo->player) // Hack to fix players sliding off of spinning polys -Red
-					{
-						fixed_t temp;
+					newxoff = FixedMul(oldxoff, c)-FixedMul(oldyoff, s) - oldxoff;
+					newyoff = FixedMul(oldyoff, c)+FixedMul(oldxoff, s) - oldyoff;
 
-						temp = FixedMul(oldxoff, c)-FixedMul(oldyoff, s);
-						oldyoff = FixedMul(oldyoff, c)+FixedMul(oldxoff, s);
-						oldxoff = temp;
-					}
-
-					newxoff = FixedMul(oldxoff, c)-FixedMul(oldyoff, s);
-					newyoff = FixedMul(oldyoff, c)+FixedMul(oldxoff, s);
-
-					Polyobj_slideThing(mo, newxoff-oldxoff, newyoff-oldyoff);
+					Polyobj_slideThing(mo, newxoff, newyoff);
 
 					if (turnthings == 2 || (turnthings == 1 && !mo->player)) {
 						mo->angle += delta;
diff --git a/src/p_user.c b/src/p_user.c
index 176b07d0a..a63022986 100644
--- a/src/p_user.c
+++ b/src/p_user.c
@@ -12174,7 +12174,9 @@ void P_PlayerThink(player_t *player)
 
 #ifdef POLYOBJECTS
 	if (player->onconveyor == 1)
-			player->cmomy = player->cmomx = 0;
+		player->onconveyor = 3;
+	else if (player->onconveyor == 3)
+		player->cmomy = player->cmomx = 0;
 #endif
 
 	P_DoSuperStuff(player);