From c8390d535a23689a53bf120a59d8f430ec67c52d Mon Sep 17 00:00:00 2001
From: Roman Fomin <rfomin@gmail.com>
Date: Thu, 14 Jul 2022 15:27:33 +0700
Subject: [PATCH] automap panning interpolation from PrBoom+ (#659)

* automap panning and zooming interpolation from PrBoom+

* fix mousewheel zoom

* restore old M_ZOOMIN M_ZOOMOUT

* remove zoom interpolation
---
 src/am_map.c | 72 +++++++++++++++++++++++++++++-----------------------
 1 file changed, 40 insertions(+), 32 deletions(-)

diff --git a/src/am_map.c b/src/am_map.c
index 00837a24..6406653a 100644
--- a/src/am_map.c
+++ b/src/am_map.c
@@ -264,6 +264,7 @@ static fixed_t ftom_zoommul; // how far the window zooms each tic (fb coords)
 
 static int64_t m_x, m_y;     // LL x,y window location on the map (map coords)
 static int64_t m_x2, m_y2;   // UR x,y window location on the map (map coords)
+static int64_t prev_m_x, prev_m_y;
 
 //
 // width/height of window on map (map coords)
@@ -292,9 +293,6 @@ static fixed_t  max_scale_mtof; // used to tell when to stop zooming in
 static int64_t old_m_w, old_m_h;
 static int64_t old_m_x, old_m_y;
 
-// old location used by the Follower routine
-static mpoint_t f_oldloc;
-
 // used by MTOF to scale from map-to-frame-buffer coords
 static fixed_t scale_mtof = INITSCALEMTOF;
 // used by FTOM to scale from frame-buffer-to-map coords (=1/scale_mtof)
@@ -510,17 +508,25 @@ void AM_changeWindowLoc(void)
   if (m_paninc.x || m_paninc.y)
   {
     followplayer = 0;
-    f_oldloc.x = D_MAXINT;
   }
 
-  incx = m_paninc.x;
-  incy = m_paninc.y;
+  if (uncapped && leveltime > oldleveltime)
+  {
+    incx = FixedMul(m_paninc.x, fractionaltic);
+    incy = FixedMul(m_paninc.y, fractionaltic);
+  }
+  else
+  {
+    incx = m_paninc.x;
+    incy = m_paninc.y;
+  }
+
   if (automaprotate)
   {
     AM_rotate(&incx, &incy, ANGLE_MAX - mapangle);
   }
-  m_x += incx;
-  m_y += incy;
+  m_x = prev_m_x + incx;
+  m_y = prev_m_y + incy;
 
   if (m_x + m_w/2 > max_x)
     m_x = max_x - m_w/2;
@@ -554,7 +560,6 @@ void AM_initVariables(void)
   automapactive = true;
   fb = screens[0];
 
-  f_oldloc.x = D_MAXINT;
   amclock = 0;
   lightlev = 0;
 
@@ -575,6 +580,7 @@ void AM_initVariables(void)
   plr = &players[pnum];
   m_x = (plr->mo->x >> FRACTOMAPBITS) - m_w/2;
   m_y = (plr->mo->y >> FRACTOMAPBITS) - m_h/2;
+  AM_Ticker(); // initialize variables for interpolation
   AM_changeWindowLoc();
 
   // for saving & restoring
@@ -864,7 +870,6 @@ boolean AM_Responder
     else if (M_InputActivated(input_map_follow))
     {
       followplayer = !followplayer;
-      f_oldloc.x = D_MAXINT;
       // Ty 03/27/98 - externalized
       plr->message = followplayer ? s_AMSTR_FOLLOWON : s_AMSTR_FOLLOWOFF;  
     }
@@ -985,17 +990,10 @@ void AM_changeWindowScale(void)
 //
 void AM_doFollowPlayer(void)
 {
-  if (f_oldloc.x != plr->mo->x || f_oldloc.y != plr->mo->y)
-  {
-    // [JN] Prevent player arrow from jittering 
-    // by not using FTOM->MTOF conversion.
-    m_x = (plr->mo->x >> FRACTOMAPBITS) - m_w/2;
-    m_y = (plr->mo->y >> FRACTOMAPBITS) - m_h/2;
-    m_x2 = m_x + m_w;
-    m_y2 = m_y + m_h;
-    f_oldloc.x = plr->mo->x;
-    f_oldloc.y = plr->mo->y;
-  }
+  m_x = (viewx >> FRACTOMAPBITS) - m_w/2;
+  m_y = (viewy >> FRACTOMAPBITS) - m_h/2;
+  m_x2 = m_x + m_w;
+  m_y2 = m_y + m_h;
 }
 
 //
@@ -1025,18 +1023,14 @@ void AM_Ticker (void)
 
   amclock++;
 
-  if (followplayer)
-    AM_doFollowPlayer();
-
-  // Change the zoom if necessary
+  // Change the zoom if necessary.
   if (ftom_zoommul != FRACUNIT)
-    AM_changeWindowScale();
-
-  // Change x,y location
-  if (m_paninc.x || m_paninc.y)
   {
-    AM_changeWindowLoc();
+    AM_changeWindowScale();
   }
+
+  prev_m_x = m_x;
+  prev_m_y = m_y;
 }
 
 
@@ -1780,8 +1774,8 @@ void AM_drawPlayers(void)
 
   if (!netgame)
   {
-    // [crispy] interpolate player arrow in non-follow mode
-    if (!followplayer && leveltime > oldleveltime)
+    // interpolate player arrow
+    if (uncapped && leveltime > oldleveltime)
     {
         pt.x = viewx >> FRACTOMAPBITS;
         pt.y = viewy >> FRACTOMAPBITS;
@@ -2082,6 +2076,20 @@ void AM_Drawer (void)
 {
   if (!automapactive) return;
 
+  // move AM_doFollowPlayer and AM_changeWindowLoc from AM_Ticker for
+  // interpolation
+
+  if (followplayer)
+  {
+    AM_doFollowPlayer();
+  }
+
+  // Change X and Y location.
+  if (m_paninc.x || m_paninc.y)
+  {
+    AM_changeWindowLoc();
+  }
+
   // [crispy] required for AM_rotatePoint()
   if (automaprotate)
   {