Change: always assume non-track station ground tile

For track station ground tile explicitly use `GROUNDSPRITE_RAIL_X` and `GROUNDSPRITE_RAIL_Y`

examples/station/example_station.nml

@@ -60,9 +60,9 @@ spriteset (cow_pen_full, "cows_cargo.png") {
     [ 360, 10, 64, 65, -31, -34 ]
 }
 
-spritelayout cow_pen_X(a) {
+spritelayout cow_pen_X {
     ground {
-        sprite: 2022 + a; // prevent railtype offset
+        sprite: 2022;
     }
     building {
         sprite: DEFAULT(0); // first sprite in active spriteset
@@ -72,9 +72,9 @@ spritelayout cow_pen_X(a) {
     }
 }
 
-spritelayout cow_pen_Y(a) {
+spritelayout cow_pen_Y {
     ground {
-        sprite: 2022 + a; // prevent railtype offset
+        sprite: 2022;
     }
     building {
         sprite: DEFAULT(1); // second sprite in active spriteset
@@ -114,7 +114,7 @@ item(FEAT_STATIONS, cow_pen) {
         non_traversable_tiles: 0xFF;
     }
     graphics {
-        sprite_layouts: [cow_pen_X(0), cow_pen_Y(0)];
+        sprite_layouts: [cow_pen_X, cow_pen_Y];
         purchase: cow_pen_half;
         LVST: random_cow_pen;
         cow_pen_empty;

nml/actions/action2layout.py

@@ -13,7 +13,7 @@
 with NML; if not, write to the Free Software Foundation, Inc.,
 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
 
-from nml import expression, generic, nmlop
+from nml import expression, generic, global_constants, nmlop
 from nml.actions import action0, action1, action2, action2real, action2var, action6, actionD, real_sprite
 from nml.ast import general, spriteblock
 
@@ -292,6 +292,14 @@ def _validate_sprite(self, name, value):
         else:
             self.sprite_from_action1 = False
             if isinstance(value, expression.ConstantNumeric):
+                # For stations always assume a non-track tile ground, unless explicit rail ground sprite.
+                if (
+                    self.feature == 0x04
+                    and self.type == Action2LayoutSpriteType.GROUND
+                    and value.value != global_constants.constant_numbers["GROUNDSPRITE_RAIL_X"]
+                    and value.value != global_constants.constant_numbers["GROUNDSPRITE_RAIL_Y"]
+                ):
+                    self.create_register(name, expression.ConstantNumeric(0))
                 generic.check_range(value.value, 0, (1 << 14) - 1, "sprite", value.pos)
                 return value
             if value.supported_by_actionD(raise_error=False):

regression/expected/example_station.nfo

@@ -81,29 +81,21 @@
 
 24 * 51 00 04 \b1 01 FF \wx0000
 1A \b2
-\b65 \dx00000000 \wx0002 82
+\b65 \dx000007E6 \wx0002 80
+\dx8000842D \wx0002 \b0 \b0 \b0 \b16 \b16 \b36 81
+\b65 \dx000007E6 \wx0002 82
 \dx8000842D \wx0002 \b0 \b0 \b0 \b16 \b16 \b36 83
-\b65 \dx00000000 \wx0002 84
-\dx8000842D \wx0002 \b0 \b0 \b0 \b16 \b16 \b36 85
 
 // Name: Station Layout@registers - Id 00
-// a : register 80
-// a : register 81
-25 * 106 02 04 FC 89
+25 * 62 02 04 FC 89
 1A 20 \dx00000000
 \2sto 1A 20 \dx00000080
-\2r 7D 80 20 \dxFFFFFFFF 	// a
-\2+ 1A 20 \dx000007E6
-\2sto 1A 20 \dx00000082
-\2r 1A 20 \dx00000000
-\2sto 1A 20 \dx00000083
 \2r 1A 20 \dx00000000
 \2sto 1A 20 \dx00000081
-\2r 7D 81 20 \dxFFFFFFFF 	// a
-\2+ 1A 20 \dx000007E6
-\2sto 1A 20 \dx00000084
+\2r 1A 20 \dx00000000
+\2sto 1A 20 \dx00000082
 \2r 1A 20 \dx00000001
-\2sto 1A 00 \dx00000085
+\2sto 1A 00 \dx00000083
 \b0
 \wx8000 // Return computed value