From 600aec3449c7cc8aaaa19f1502c7549e97dc1023 Mon Sep 17 00:00:00 2001
From: James R <justsomejames2@gmail.com>
Date: Wed, 15 Nov 2023 14:48:53 -0800
Subject: [PATCH] renderhitbox: shown MF_PAPERCOLLISION correctly

---
 src/r_bbox.c     | 43 +++++++++++++++++++++++++++----------------
 src/r_things.cpp | 35 ++++++++++++++++++++++++++---------
 2 files changed, 53 insertions(+), 25 deletions(-)

diff --git a/src/r_bbox.c b/src/r_bbox.c
index ce4f3d758..d484c3b51 100644
--- a/src/r_bbox.c
+++ b/src/r_bbox.c
@@ -204,29 +204,40 @@ void R_DrawThingBoundingBox(vissprite_t *vis)
 		.color = R_GetBoundingBoxColor(vis->mobj),
 	};
 
-	// 1--3
-	// |  |
-	// 0--2
+	if (vis->mobjflags & MF_PAPERCOLLISION)
+	{
+		// 0--1
 
-	// left
+		draw_bbox_col(&bb, 0, tx - rc, ty - rs); // left
+		draw_bbox_col(&bb, 1, tx + rc, ty + rs); // right
+		draw_bbox_row(&bb, 0, 1); // connect both
+	}
+	else
+	{
+		// 1--3
+		// |  |
+		// 0--2
 
-	draw_bbox_col(&bb, 0, tx, ty); // bottom
-	draw_bbox_col(&bb, 1, tx - rc, ty + rs); // top
+		// left
 
-	// right
+		draw_bbox_col(&bb, 0, tx, ty); // bottom
+		draw_bbox_col(&bb, 1, tx - rc, ty + rs); // top
 
-	tx += rs;
-	ty += rc;
+		// right
 
-	draw_bbox_col(&bb, 2, tx, ty); // bottom
-	draw_bbox_col(&bb, 3, tx - rc, ty + rs); // top
+		tx += rs;
+		ty += rc;
 
-	// connect all four columns
+		draw_bbox_col(&bb, 2, tx, ty); // bottom
+		draw_bbox_col(&bb, 3, tx - rc, ty + rs); // top
 
-	draw_bbox_row(&bb, 0, 1);
-	draw_bbox_row(&bb, 1, 3);
-	draw_bbox_row(&bb, 3, 2);
-	draw_bbox_row(&bb, 2, 0);
+		// connect all four columns
+
+		draw_bbox_row(&bb, 0, 1);
+		draw_bbox_row(&bb, 1, 3);
+		draw_bbox_row(&bb, 3, 2);
+		draw_bbox_row(&bb, 2, 0);
+	}
 }
 
 static boolean is_tangible (mobj_t *thing)
diff --git a/src/r_things.cpp b/src/r_things.cpp
index deacfce92..37dcc3bf4 100644
--- a/src/r_things.cpp
+++ b/src/r_things.cpp
@@ -1586,13 +1586,22 @@ static void R_ProjectBoundingBox(mobj_t *thing, vissprite_t *vis)
 		R_InterpolateMobjState(thing, FRACUNIT, &interp);
 	}
 
-	// 1--3
-	// |  |
-	// 0--2
-
-	// start in the (0) corner
-	gx = interp.x - thing->radius - viewx;
-	gy = interp.y - thing->radius - viewy;
+	if (thing->flags & MF_PAPERCOLLISION)
+	{
+		// 0--1
+		// start in the middle
+		gx = interp.x - viewx;
+		gy = interp.y - viewy;
+	}
+	else
+	{
+		// 1--3
+		// |  |
+		// 0--2
+		// start in the (0) corner
+		gx = interp.x - thing->radius - viewx;
+		gy = interp.y - thing->radius - viewy;
+	}
 
 	tz = FixedMul(gx, viewcos) + FixedMul(gy, viewsin);
 
@@ -1620,8 +1629,16 @@ static void R_ProjectBoundingBox(mobj_t *thing, vissprite_t *vis)
 	box->gx = tx;
 	box->gy = tz;
 
-	box->scale = 2 * FixedMul(thing->radius, viewsin);
-	box->xscale = 2 * FixedMul(thing->radius, viewcos);
+	if (thing->flags & MF_PAPERCOLLISION)
+	{
+		box->scale = FixedMul(thing->radius, FCOS(viewangle - interp.angle));
+		box->xscale = FixedMul(thing->radius, FSIN(viewangle - interp.angle));
+	}
+	else
+	{
+		box->scale = 2 * FixedMul(thing->radius, viewsin);
+		box->xscale = 2 * FixedMul(thing->radius, viewcos);
+	}
 
 	box->pz = interp.z;
 	box->pzt = box->pz + box->thingheight;