From 47a43d054425d91e06a543794ae4b80e6e0a96d2 Mon Sep 17 00:00:00 2001
From: JugadorXEI <eugeniom9@gmail.com>
Date: Tue, 12 Aug 2025 14:50:43 +0200
Subject: [PATCH] Fix loops so that they work in all directions

---
 src/objects/loops.cpp | 85 +++----------------------------------------
 src/p_loop.c          | 14 +++----
 2 files changed, 11 insertions(+), 88 deletions(-)

diff --git a/src/objects/loops.cpp b/src/objects/loops.cpp
index ddb401891..cb512d396 100644
--- a/src/objects/loops.cpp
+++ b/src/objects/loops.cpp
@@ -151,81 +151,6 @@ get_binary_direction
 	}
 }
 
-static std::optional<vector2_t>
-intersect
-(		const mobj_t * anchor,
-		const mobj_t * toucher)
-{
-	struct Line
-	{
-		angle_t a;
-		vector2_t o;
-
-		angle_t k = AbsAngle(a);
-
-		Line(vector2_t o_, angle_t a_) : a(a_), o(o_) {}
-
-		bool vertical() const { return k == ANGLE_90; }
-
-		fixed_t m() const
-		{
-			// tangent table is offset 90 degrees
-			return FTAN(a - ANGLE_90);
-		}
-
-		fixed_t b() const
-		{
-			return o.y - FixedMul(o.x, m());
-		}
-
-		fixed_t y(fixed_t x) const
-		{
-			return FixedMul(m(), x) + b();
-		}
-	};
-
-	if (toucher->momx == 0 && toucher->momy == 0)
-	{
-		// undefined angle
-		return {};
-	}
-
-	Line a({toucher->x, toucher->y},
-		R_PointToAngle2(0, 0, toucher->momx, toucher->momy));
-
-	Line b({anchor->x, anchor->y}, anchor->angle + ANGLE_90);
-
-	if (a.k == b.k)
-	{
-		// parallel lines do not intersect
-		return {};
-	}
-
-	vector2_t v;
-
-	auto v_intersect = [&v](Line &a, Line &b)
-	{
-		if (a.vertical())
-		{
-			return false;
-		}
-
-		v.x = b.o.x;
-		v.y = a.y(v.x);
-
-		return true;
-	};
-
-	if (!v_intersect(a, b) && !v_intersect(b, a))
-	{
-		// untested!
-		v.x = FixedDiv(a.b() - b.b(), b.m() - a.m());
-		v.y = a.y(v.x);
-	}
-
-	return v;
-}
-
 mobj_t *
 Obj_FindLoopCenter (const mtag_t tag)
 {
@@ -330,10 +255,12 @@ Obj_LoopEndpointCollide
 	{
 		set_shiftxy(player, anchor);
 
-		vector2_t i = intersect(anchor, toucher)
-			.value_or(vector2_t {px, py});
-
-		s->origin_shift = {i.x - px, i.y - py};
+		const fixed_t magnitude = R_PointToDist2(0, 0, px, py);
+		const fixed_t newX = FixedDiv(px, magnitude);
+		const fixed_t newY = FixedDiv(py, magnitude);
+		
+		s->origin_shift = {FixedMul(newX, FCOS(anchor->angle)),
+			FixedMul(newY, FSIN(anchor->angle))};
 	}
 
 	flip = get_binary_direction(pitch, toucher);
diff --git a/src/p_loop.c b/src/p_loop.c
index 9ddf22f7b..93ef4c060 100644
--- a/src/p_loop.c
+++ b/src/p_loop.c
@@ -101,7 +101,7 @@ boolean P_PlayerOrbit(player_t *player)
 	fixed_t r, xy, z;
 	fixed_t xs, ys;
 
-	fixed_t step, th, left;
+	fixed_t step, left;
 
 	fixed_t grav;
 
@@ -136,16 +136,12 @@ boolean P_PlayerOrbit(player_t *player)
 
 	// XY shift is transformed on wave scale; less movement
 	// at start and end of rotation, more halfway.
-	th = FSIN(pitch_normal - ANGLE_90);
-
-	xs = FixedMul(s->shift.x, th);
-	ys = FixedMul(s->shift.y, th);
+	xs = FixedMul(s->shift.x, FCOS(pitch_normal));
+	ys = FixedMul(s->shift.y, FSIN(pitch_normal - ANGLE_90));
 
 	// Interpolate 0-1 over entire rotation.
-	th = FSIN(pitch_normal / 2);
-
-	xs += FixedMul(s->origin_shift.x, th);
-	ys += FixedMul(s->origin_shift.y, th);
+	xs += FixedMul(s->origin_shift.x, FCOS(pitch_normal));
+	ys += FixedMul(s->origin_shift.y, FSIN(pitch_normal - ANGLE_90));
 
 	xs += FixedMul(xy, FCOS(s->yaw));
 	ys += FixedMul(xy, FSIN(s->yaw));