Ticket #8069: layering.diff

scummvm/scumm/gfx.cpp

@@ -924 +924 @@
                         }
                 }
                 CHECK_HEAP;
-                if (flag & dbDrawMaskOnBoth) {
-                        _z_plane_ptr = zplane_list[1] + READ_LE_UINT16(zplane_list[1] + stripnr * 2 + 8);
-                        _mask_ptr_dest = _vm->getResourceAddress(rtBuffer, 9) + y * NUM_STRIPS + x;
-                        if (_useOrDecompress && flag & dbAllowMaskOr)
-                                decompressMaskImgOr();
-                        else
-                                decompressMaskImg();
-                }
-
-                for (i = 1; i < numzbuf; i++) {
-                        uint16 offs;
-
-                        if (!zplane_list[i])
-                                continue;
-
-                        if (_vm->_features & GF_SMALL_HEADER)
-                                if (_vm->_features & GF_OLD256)
-                                        offs = READ_LE_UINT16(zplane_list[i] + stripnr * 2 + 4);
-                                else
-                                        offs = READ_LE_UINT16(zplane_list[i] + stripnr * 2 + 2);
-                        else
-                                offs = READ_LE_UINT16(zplane_list[i] + stripnr * 2 + 8);
-
-                        _mask_ptr_dest = _vm->getResourceAddress(rtBuffer, 9) + y * NUM_STRIPS + x + _imgBufOffs[i];
 
-                        if (offs) {
-                                _z_plane_ptr = zplane_list[i] + offs;
+                // Sam & Max uses dbDrawMaskOnAll for things like the inventory
+                // box and the speech icons. While these objects only have one
+                // mask, it should be applied to all the Z-planes in the room,
+                // i.e. they should mask every actor.
+                //
+                // This flag used to be called dbDrawMaskOnBoth, and all it
+                // would do was to mask Z-plane 0. (Z-plane 1 would also be
+                // masked, because what is now the else-clause used to be run
+                // always.) While this seems to be the only way there is to
+                // mask Z-plane 0, this wasn't good enough since actors in
+                // Z-planes >= 2 would not be masked.
+                //
+                // The flag is also used by The Dig and Full Throttle, but I
+                // don't know what for. At the time of writing, these games
+                // are still too unstable for me to investigate.
 
+                if (flag & dbDrawMaskOnAll) {
+                        _z_plane_ptr = zplane_list[1] + READ_LE_UINT16(zplane_list[1] + stripnr * 2 + 8);
+                        for (i = 0; i < numzbuf; i++) {
+                                _mask_ptr_dest = _vm->getResourceAddress(rtBuffer, 9) + y * NUM_STRIPS + x + _imgBufOffs[i];
                                 if (_useOrDecompress && flag & dbAllowMaskOr)
                                         decompressMaskImgOr();
                                 else
                                         decompressMaskImg();
-                        } else {
-                                if (_useOrDecompress && flag & dbAllowMaskOr);  /* nothing */
-                                else
-                                        for (int h = 0; h < _numLinesToProcess; h++)
-                                                _mask_ptr_dest[h * NUM_STRIPS] = 0;
-                                /* needs better abstraction, FIXME */
+                        }
+                } else {
+                        for (i = 1; i < numzbuf; i++) {
+                                uint16 offs;
+
+                                if (!zplane_list[i])
+                                        continue;
+
+                                if (_vm->_features & GF_SMALL_HEADER) {
+                                        if (_vm->_features & GF_OLD256)
+                                                offs = READ_LE_UINT16(zplane_list[i] + stripnr * 2 + 4);
+                                        else
+                                                offs = READ_LE_UINT16(zplane_list[i] + stripnr * 2 + 2);
+                                } else
+                                        offs = READ_LE_UINT16(zplane_list[i] + stripnr * 2 + 8);
+
+                                _mask_ptr_dest = _vm->getResourceAddress(rtBuffer, 9) + y * NUM_STRIPS + x + _imgBufOffs[i];
+
+                                if (offs) {
+                                        _z_plane_ptr = zplane_list[i] + offs;
+
+                                        if (_useOrDecompress && flag & dbAllowMaskOr)
+                                                decompressMaskImgOr();
+                                        else
+                                                decompressMaskImg();
+                                } else {
+                                        if (!(_useOrDecompress && flag & dbAllowMaskOr));
+                                                for (int h = 0; h < _numLinesToProcess; h++)
+                                                        _mask_ptr_dest[h * NUM_STRIPS] = 0;
+                                        /* needs better abstraction, FIXME */
+                                }
                         }
                 }
                 CHECK_HEAP;

scummvm/scumm/gfx.h

@@ -184 +184 @@
 
         enum DrawBitmapFlags {
                 dbAllowMaskOr = 1,
-                dbDrawMaskOnBoth = 2,
+                dbDrawMaskOnAll = 2,
                 dbClear = 4
         };
 };

scummvm/scumm/object.cpp

@@ -378 +378 @@
                 // Sam & Max needs this to fix object-layering problems with
                 // the inventory and conversation icons.
                 if ((_features & GF_AFTER_V7 || _gameId == GID_SAMNMAX) && getClass(od->obj_nr, 22))
-                        flags |= Gdi::dbDrawMaskOnBoth;
+                        flags |= Gdi::dbDrawMaskOnAll;
                 gdi.drawBitmap(ptr, _curVirtScreen, x, ypos, height, x - xpos, numstrip, flags);
         }
 }