diff --git a/polymer/eduke32/build/src/build.c b/polymer/eduke32/build/src/build.c
index 8df4e6d4f..ecfdf4f5c 100644
--- a/polymer/eduke32/build/src/build.c
+++ b/polymer/eduke32/build/src/build.c
@@ -513,36 +513,40 @@ int32_t app_main(int32_t argc, const char **argv)
     // init dummy texture for YAX
     // must be after loadpics(), which inits BUILD's cache
 
-    i = MAXTILES-1;
-    if (tilesizx[i]==0 && tilesizy[i]==0)
-    {
-        static char R[8*16] = { //
-            0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0,
-            0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0,
-            0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0,
-            0, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0,
-            0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0,
-            0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0,
-            0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0,
-        };
+    for (i=MAXTILES-1; i>=MAXTILES-2; i--)
+        if (tilesizx[i]==0 && tilesizy[i]==0)
+        {
+            static char R[8*16] = { //
+                0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0,
+                0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0,
+                0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0,
+                0, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0,
+                0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0,
+                0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0,
+                0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0,
+            };
 
-        char *newtile;
-        int32_t sx=32, sy=32, col, j;
+            char *newtile;
+            int32_t sx=32, sy=32, col, j;
 
-        walock[i] = 255; // permanent tile
-        picsiz[i] = 5 + (5<<4);
-        tilesizx[i] = sx; tilesizy[i] = sy;
-        allocache(&waloff[i], sx*sy, &walock[i]);
-        newtile = (char *)waloff[i];
+            walock[i] = 255; // permanent tile
+            picsiz[i] = 5 + (5<<4);
+            tilesizx[i] = sx; tilesizy[i] = sy;
+            allocache(&waloff[i], sx*sy, &walock[i]);
+            newtile = (char *)waloff[i];
 
-        col = getclosestcol(128>>2, 128>>2, 0);
-        for (j=0; j<(signed)sizeof(R); j++)
-            R[j] *= col;
+            if (i==MAXTILES-1)
+                col = getclosestcol(128>>2, 128>>2, 0);
+            else
+                col = getclosestcol(63, 0, 63);
+            for (j=0; j<(signed)sizeof(R); j++)
+                if (R[j])
+                    R[j] = col;
 
-        Bmemset(newtile, 0, sx*sy);
-        for (j=0; j<8; j++)
-            Bmemcpy(&newtile[32*j], &R[16*j], 16);
-    }
+            Bmemset(newtile, 0, sx*sy);
+            for (j=0; j<8; j++)
+                Bmemcpy(&newtile[32*j], &R[16*j], 16);
+        }
 #endif
 
     Bstrcpy(kensig,"Uses BUILD technology by Ken Silverman");
diff --git a/polymer/eduke32/build/src/engine.c b/polymer/eduke32/build/src/engine.c
index 9a767056e..a56ba06fe 100644
--- a/polymer/eduke32/build/src/engine.c
+++ b/polymer/eduke32/build/src/engine.c
@@ -620,7 +620,7 @@ static void yax_tweakpicnums(int32_t bunchnum, int32_t cf, int32_t restore)
             {
                 opicnum[cf][i] = SECTORFLD(i,picnum, cf);
                 if (editstatus && showinvisibility)
-                    SECTORFLD(i,picnum, cf) = MAXTILES-1;
+                    SECTORFLD(i,picnum, cf) = MAXTILES-1-((SECTORFLD(i,stat, cf)&4096)>>12);
                 else
                     SECTORFLD(i,picnum, cf) = 13; //FOF;
             }
@@ -3717,6 +3717,48 @@ static inline void ceilspritescan(int32_t x1, int32_t x2)
     faketimerhandler();
 }
 
+////////// translucent slope vline, based on a-c.c's slopevlin //////////
+static int32_t gglogx, gglogy, ggpinc;
+static char *ggbuf, *ggpal;
+
+static void setupslopevlin_alsotrans(int32_t logylogx, intptr_t bufplc, int32_t pinc)
+{
+    setupslopevlin(logylogx, bufplc, pinc);
+    gglogx = (logylogx&255); gglogy = (logylogx>>8);
+    ggbuf = (char *)bufplc; ggpinc = pinc;
+    ggpal = palookup[globalpal] + (getpalookup(0,globalshade)<<8);
+}
+
+static void tslopevlin(intptr_t p, int32_t i, intptr_t slopaloffs, int32_t cnt, int32_t bx, int32_t by)
+{
+    intptr_t *slopalptr;
+    int32_t bz, bzinc;
+    uint32_t u, v;
+
+    char ch;
+
+    bz = asm3; bzinc = (asm1>>3);
+    slopalptr = (intptr_t *)slopaloffs;
+
+    for (; cnt>0; cnt--)
+    {
+        i = krecipasm(bz>>6); bz += bzinc;
+        u = bx+globalx3*i;
+        v = by+globaly3*i;
+        ch = *(char *)(slopalptr[0] + ggbuf[((u>>(32-gglogx))<<gglogy)+(v>>(32-gglogy))]);
+        if (globalorientation&128)
+        {
+            if (ch != 255) *((char *)p) = transluc[*((char *)p)+(ggpal[ch]<<8)];
+        }
+        else
+        {
+            if (ch != 255) *((char *)p) = transluc[(*((char *)p)<<8)+ggpal[ch]];
+        }
+
+        slopalptr--;
+        p += ggpinc;
+    }
+}
 
 //
 // grouscan (internal)
@@ -3835,7 +3877,8 @@ static void grouscan(int32_t dax1, int32_t dax2, int32_t sectnum, char dastat)
     globvis = mulscale16(globvis,xdimscale);
     j = FP_OFF(palookup[globalpal]);
 
-    setupslopevlin(((int32_t)(picsiz[globalpicnum]&15))+(((int32_t)(picsiz[globalpicnum]>>4))<<8),waloff[globalpicnum],-ylookup[1]);
+    setupslopevlin_alsotrans(((int32_t)(picsiz[globalpicnum]&15))+(((int32_t)(picsiz[globalpicnum]>>4))<<8),
+                             waloff[globalpicnum],-ylookup[1]);
 
     l = (globalzd>>16);
 
@@ -3870,7 +3913,10 @@ static void grouscan(int32_t dax1, int32_t dax2, int32_t sectnum, char dastat)
             globalx3 = (globalx2>>10);
             globaly3 = (globaly2>>10);
             asm3 = mulscale16(y2,globalzd) + (globalzx>>6);
-            slopevlin(ylookup[y2]+x+frameoffset,krecipasm(asm3>>3),(intptr_t)nptr2,y2-y1+1,globalx1,globaly1);
+            if ((globalorientation&256)==0)
+                slopevlin(ylookup[y2]+x+frameoffset,krecipasm(asm3>>3),(intptr_t)nptr2,y2-y1+1,globalx1,globaly1);
+            else
+                tslopevlin(ylookup[y2]+x+frameoffset,krecipasm(asm3>>3),(intptr_t)nptr2,y2-y1+1,globalx1,globaly1);
 
             if ((x&15) == 0) faketimerhandler();
         }
@@ -4193,7 +4239,11 @@ static void drawalls(int32_t bunch)
             {
                 if ((cz[2] <= cz[0]) && (cz[3] <= cz[1]))
                 {
-                    if (globparaceilclip)
+                    if (globparaceilclip
+#ifdef YAX_ENABLE
+                            || (sector[globalcursectnum].ceilingstat&4096)
+#endif
+)
                         for (x=x1; x<=x2; x++)
                             if (uplc[x] > umost[x])
                                 if (umost[x] <= dmost[x])
@@ -4285,8 +4335,7 @@ static void drawalls(int32_t bunch)
                 {
                     if (globparaflorclip
 #ifdef YAX_ENABLE
-//                        || ((sec->floorstat&2) && yax_globallev < YAX_MAXDRAWS)
-//                            || yax_getbunch(wallnum, YAX_FLOOR) < 0
+                            || (sector[globalcursectnum].floorstat&4096)
 #endif
                         )
                         for (x=x1; x<=x2; x++)
@@ -14023,21 +14072,11 @@ static void drawscreen_drawwall(int32_t i, int32_t posxe, int32_t posye, int32_t
         if (!m32_sideview && (j >= 0) && (i > j)) return;
     }
 
-#if 1
-//def YAX_ENABLE
     if ((graywallbitmap[i>>3] & (1<<(i&7))) || (j>=0 && (graywallbitmap[j>>3] & (1<<(j&7)))))
     {
-#ifdef YAX_ENABLE
-        // yax'ed grayed out walls are always cleared from the overhead map.
-        // normal walls cleared out due to editorzrange are displayed, though
-        if (!m32_sideview && ((wall[i].cstat&YAX_NEXTWALLBITS) || (j>=0 && wall[j].cstat&YAX_NEXTWALLBITS)))
-            return;
-#endif
         col = 8;
     }
-    else
-#endif
-    if (j < 0)
+    else if (j < 0)
     {
         col = 15;
         if (i == linehighlight)
@@ -14395,8 +14434,16 @@ void draw2dscreen(const vec3_t *pos, int16_t cursectnum, int16_t ange, int32_t z
     m32_swcnt = 0;
 
     if (!m32_sideview)
+    {
         for (i=numwalls-1; i>=0; i--)
+#ifdef YAX_ENABLE
+            if (graywallbitmap[(i)>>3]&(1<<((i)&7)))
+                drawscreen_drawwall(i,posxe,posye,posze,zoome);
+        for (i=numwalls-1; i>=0; i--)
+            if ((graywallbitmap[(i)>>3]&(1<<((i)&7)))==0)
+#endif
             drawscreen_drawwall(i,posxe,posye,posze,zoome);
+    }
     else
     {
         for (i=0; i<numsectors; i++)
@@ -14852,7 +14899,7 @@ int32_t screencapture_png(const char *filename, char inverseit, const char *vers
     }
 
     png_set_gAMA(png_ptr, info_ptr, vid_gamma);  // 1.0/vid_gamma ?
-    png_set_sRGB(png_ptr, info_ptr, PNG_sRGB_INTENT_SATURATION);  // hm...
+//    png_set_sRGB(png_ptr, info_ptr, PNG_sRGB_INTENT_SATURATION);  // hm...
 
     text = (png_textp)png_malloc(png_ptr, 2*png_sizeof(png_text));
     text[0].compression = PNG_TEXT_COMPRESSION_NONE;
diff --git a/polymer/eduke32/build/src/engine_priv.h b/polymer/eduke32/build/src/engine_priv.h
index 4143f3a66..4bc54b8ec 100644
--- a/polymer/eduke32/build/src/engine_priv.h
+++ b/polymer/eduke32/build/src/engine_priv.h
@@ -10,7 +10,7 @@
 
 // uncomment to clear the screen before each top-level draw
 // (classic only)
-// #define ENGINE_CLEAR_SCREEN
+//#define ENGINE_CLEAR_SCREEN
 
 #ifdef YAX_ENABLE
 # define YAX_MAXDRAWS 8
diff --git a/polymer/eduke32/source/m32structures.c b/polymer/eduke32/source/m32structures.c
index 6e6bb9f3d..5ad1181ff 100644
--- a/polymer/eduke32/source/m32structures.c
+++ b/polymer/eduke32/source/m32structures.c
@@ -72,11 +72,12 @@ static int32_t __fastcall VM_AccessWall(int32_t how, int32_t lVar1, int32_t lLab
         case WALL_NEXTWALL: wall[i].nextwall=lValue; break;
         case WALL_NEXTSECTOR: wall[i].nextsector=lValue; break;
         case WALL_CSTAT:
-            wall[i].cstat = lValue & (0x03ff
 #ifdef YAX_ENABLE
-                                      | (m32_script_expertmode ? YAX_NEXTWALLBITS : 0)
+            if (!m32_script_expertmode)
+                SET_PROTECT_BITS(wall[i].cstat, lValue, YAX_NEXTWALLBITS);
+            else
 #endif
-                );
+            wall[i].cstat = lValue;
             break;
         case WALL_PICNUM: wall[i].picnum=lValue; break;
         case WALL_OVERPICNUM: wall[i].overpicnum=lValue; break;
@@ -170,16 +171,24 @@ static int32_t __fastcall VM_AccessSector(int32_t how, int32_t lVar1, int32_t lL
         case SECTOR_CEILINGZ: sector[i].ceilingz=lValue; break;
         case SECTOR_FLOORZ: sector[i].floorz=lValue; break;
         case SECTOR_CEILINGSTAT:
-            sector[i].ceilingstat = lValue&0x01fd;
+#ifdef YAX_ENABLE
+            if (!m32_script_expertmode)
+                SET_PROTECT_BITS(sector[i].ceilingstat, lValue, YAX_BIT);
+            else
+#endif
+                sector[i].ceilingstat = lValue;
             break;
         case SECTOR_FLOORSTAT:
-            sector[i].floorstat = lValue&0x01fd;
+#ifdef YAX_ENABLE
+            if (!m32_script_expertmode)
+                SET_PROTECT_BITS(sector[i].floorstat, lValue, YAX_BIT);
+            else
+#endif
+                sector[i].floorstat = lValue;
             break;
         case SECTOR_CEILINGPICNUM: sector[i].ceilingpicnum=lValue; break;
         case SECTOR_CEILINGSLOPE:
-            sector[i].ceilingheinum = lValue;
-            if (lValue) sector[i].ceilingstat |= 2;
-            else sector[i].ceilingstat &= ~2;
+            setslope(i, 0, lValue);
             break;
         case SECTOR_CEILINGSHADE: sector[i].ceilingshade=lValue; break;
         case SECTOR_CEILINGPAL: sector[i].ceilingpal=lValue; break;
@@ -187,9 +196,7 @@ static int32_t __fastcall VM_AccessSector(int32_t how, int32_t lVar1, int32_t lL
         case SECTOR_CEILINGYPANNING: sector[i].ceilingypanning=lValue; break;
         case SECTOR_FLOORPICNUM: sector[i].floorpicnum=lValue; break;
         case SECTOR_FLOORSLOPE:
-            sector[i].floorheinum = lValue;
-            if (lValue) sector[i].floorstat |= 2;
-            else sector[i].floorstat &= ~2;
+            setslope(i, 1, lValue);
             break;
         case SECTOR_FLOORSHADE: sector[i].floorshade=lValue; break;
         case SECTOR_FLOORPAL: sector[i].floorpal=lValue; break;