diff --git a/polymer/eduke32/build/include/build.h b/polymer/eduke32/build/include/build.h
index 735027fc2..26dcc6aa0 100644
--- a/polymer/eduke32/build/include/build.h
+++ b/polymer/eduke32/build/include/build.h
@@ -150,6 +150,9 @@ void yax_drawrooms(void (*SpriteAnimFunc)(int32_t,int32_t,int32_t,int32_t),
 // max x/y val (= max editorgridextent in Mapster32)
 #define BXY_MAX 524288
 
+// ROTATESPRITE_MAX-1 is the mask of all externally available orientation bits
+#define ROTATESPRITE_MAX 2048
+
     //Make all variables in BUILD.H defined in the ENGINE,
     //and externed in GAME
 #ifdef ENGINE
diff --git a/polymer/eduke32/build/src/engine.c b/polymer/eduke32/build/src/engine.c
index 2de0a24a6..fa7891056 100644
--- a/polymer/eduke32/build/src/engine.c
+++ b/polymer/eduke32/build/src/engine.c
@@ -6856,7 +6856,7 @@ void dorotspr_handle_bit2(int32_t *sxptr, int32_t *syptr, int32_t *z, int32_t da
         if (!(dastat & 1024) && 4*ydim <= 3*xdim)
         {
             *ret_yxaspect = (12<<16)/10;
-            *ret_xyaspect = ((1<<16)*10)/12;
+            *ret_xyaspect = (10<<16)/12;
 
             // *sxptr and *syptr and *z are left unchanged
         }
@@ -6869,61 +6869,65 @@ void dorotspr_handle_bit2(int32_t *sxptr, int32_t *syptr, int32_t *z, int32_t da
         const int32_t oxdim = xdim;
         int32_t xdim = oxdim;  // SHADOWS global
 
-        int32_t x, sx=*sxptr, sy=*syptr;
+        int32_t zoomsc, sx=*sxptr, sy=*syptr;
         int32_t ouryxaspect = yxaspect, ourxyaspect = xyaspect;
 
+        // screen center to s[xy], 320<<16 coords.
+        const int32_t normxofs = sx-(320<<15), normyofs = sy-(200<<15);
+
         if (!(dastat & 1024) && 4*ydim <= 3*xdim)
         {
             xdim = (4*ydim)/3;
 
             ouryxaspect = (12<<16)/10;
-            ourxyaspect = ((1<<16)*10)/12;
+            ourxyaspect = (10<<16)/12;
         }
 
         // nasty hacks go here
         if (!(dastat&8))
         {
-            const int32_t cxs = cx1_plus_cx2+2;
-            int32_t sthelse;
+            const int32_t twice_midcx = cx1_plus_cx2+2;
 
-            x = xdimenscale;   //= scale(xdimen,yxaspect,320);
+            // screen x center to sx1, scaled to viewport
+            const int32_t scaledxofs = scale(normxofs, scale(xdimen, xdim, oxdim), 320);
 
-            sthelse = scale(sx-(320<<15), scale(xdimen, xdim, oxdim), 320);
+            int32_t xbord = 0;
 
+            if (dastat & (256|512))
             {
-                int32_t xbord = 0;
+                xbord = scale(oxdim-xdim, twice_midcx, oxdim);
 
-                if (dastat & (256|512))
-                {
-                    xbord = scale(oxdim-xdim, cxs, oxdim);
-
-                    if ((dastat & 512)==0)
-                        xbord = -xbord;
-                }
-
-                sx = ((cxs+xbord)<<15) + sthelse;
+                if ((dastat & 512)==0)
+                    xbord = -xbord;
             }
 
-            sy = ((cy1_plus_cy2+2)<<15)+mulscale16(sy-(200<<15), x);
+            sx = ((twice_midcx+xbord)<<15) + scaledxofs;
+
+            zoomsc = xdimenscale;   //= scale(xdimen,yxaspect,320);
+            sy = ((cy1_plus_cy2+2)<<15) + mulscale16(normyofs, zoomsc);
         }
         else
         {
             //If not clipping to startmosts, & auto-scaling on, as a
             //hard-coded bonus, scale to full screen instead
 
-            x = scale(xdim,ouryxaspect,320);
-            sx = (xdim<<15)+32768 + scale(sx-(320<<15),xdim,320);
-            sy = (ydim<<15)+32768 + mulscale16(sy-(200<<15),x);
+            sx = (xdim<<15)+32768 + scale(normxofs,xdim,320);
 
             if (dastat & 512)
                 sx += (oxdim-xdim)<<16;
             else if ((dastat & 256) == 0)
                 sx += (oxdim-xdim)<<15;
+
+            if (dastat&(1<<29))
+                sx += oxdim<<15;
+
+            zoomsc = scale(xdim, ouryxaspect, 320);
+            sy = (ydim<<15)+32768 + mulscale16(normyofs, zoomsc);
         }
 
         *sxptr = sx;
         *syptr = sy;
-        *z = mulscale16(*z,x);
+        *z = mulscale16(*z, zoomsc);
 
         *ret_yxaspect = ouryxaspect;
         *ret_xyaspect = ourxyaspect;
@@ -13630,6 +13634,10 @@ void rotatesprite(int32_t sx, int32_t sy, int32_t z, int16_t a, int16_t picnum,
     if (picanm[picnum]&192) picnum += animateoffs(picnum,(int16_t)0xc000);
     if ((tilesizx[picnum] <= 0) || (tilesizy[picnum] <= 0)) return;
 
+    // Experimental / development bits. ONLY FOR INTERNAL USE!
+    //  bit (1<<29): see dorotspr_handle_bit2
+    ////////////////////
+
     if (((dastat&128) == 0) || (numpages < 2) || (beforedrawrooms != 0))
     {
         begindrawing(); //{{{
diff --git a/polymer/eduke32/source/game.c b/polymer/eduke32/source/game.c
index e8062ba73..0e1b13082 100644
--- a/polymer/eduke32/source/game.c
+++ b/polymer/eduke32/source/game.c
@@ -60,8 +60,6 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 # include "lunatic.h"
 #endif
 
-#define ROTATESPRITE_MAX 2048
-
 #if KRANDDEBUG
 # define GAME_INLINE
 # define GAME_STATIC
diff --git a/polymer/eduke32/source/gameexec.c b/polymer/eduke32/source/gameexec.c
index f8d951f57..8ddc28ae4 100644
--- a/polymer/eduke32/source/gameexec.c
+++ b/polymer/eduke32/source/gameexec.c
@@ -1966,6 +1966,8 @@ nullquote:
                 int32_t x=Gv_GetVarX(*insptr++), y=Gv_GetVarX(*insptr++), tilenum=Gv_GetVarX(*insptr++);
                 int32_t shade=Gv_GetVarX(*insptr++), orientation=Gv_GetVarX(*insptr++);
 
+                orientation &= (ROTATESPRITE_MAX-1);
+
                 switch (tw)
                 {
                 case CON_MYOS:
@@ -2510,6 +2512,8 @@ nullquote:
                     continue;
                 }
 
+                orientation &= (ROTATESPRITE_MAX-1);
+
                 rotatesprite(x,y,z,a,tilenum,shade,pal,2|orientation,x1,y1,x2,y2);
                 continue;
             }
@@ -2546,6 +2550,8 @@ nullquote:
                     continue;
                 }
 
+                orientation &= (ROTATESPRITE_MAX-1);
+
                 G_PrintGameText(0,tilenum,x>>1,y,ScriptQuotes[q],shade,pal,orientation,x1,y1,x2,y2,z);
                 continue;
             }
@@ -2569,6 +2575,8 @@ nullquote:
                     continue;
                 }
 
+                orientation &= (ROTATESPRITE_MAX-1);
+
                 G_DrawTXDigiNumZ(tilenum,x,y,q,shade,pal,orientation,x1,y1,x2,y2,z);
                 continue;
             }