+void CheckNextToConditions(int x, int y)
+{
+ int element = Tile[x][y];
+
+ if (IS_PLAYER(x, y))
+ TestIfPlayerNextToCustomElement(x, y);
+
+ if (CAN_CHANGE_OR_HAS_ACTION(element) &&
+ HAS_ANY_CHANGE_EVENT(element, CE_NEXT_TO_X))
+ TestIfElementNextToCustomElement(x, y);
+}
+
+void TestIfPlayerNextToCustomElement(int x, int y)
+{
+ static int xy[4][2] =
+ {
+ { 0, -1 },
+ { -1, 0 },
+ { +1, 0 },
+ { 0, +1 }
+ };
+ static int trigger_sides[4][2] =
+ {
+ // center side border side
+ { CH_SIDE_TOP, CH_SIDE_BOTTOM }, // check top
+ { CH_SIDE_LEFT, CH_SIDE_RIGHT }, // check left
+ { CH_SIDE_RIGHT, CH_SIDE_LEFT }, // check right
+ { CH_SIDE_BOTTOM, CH_SIDE_TOP } // check bottom
+ };
+ int i;
+
+ if (!IS_PLAYER(x, y))
+ return;
+
+ struct PlayerInfo *player = PLAYERINFO(x, y);
+
+ if (player->is_moving)
+ return;
+
+ for (i = 0; i < NUM_DIRECTIONS; i++)
+ {
+ int xx = x + xy[i][0];
+ int yy = y + xy[i][1];
+ int border_side = trigger_sides[i][1];
+ int border_element;
+
+ if (!IN_LEV_FIELD(xx, yy))
+ continue;
+
+ if (IS_MOVING(xx, yy) || IS_BLOCKED(xx, yy))
+ continue; // center and border element not connected
+
+ border_element = Tile[xx][yy];
+
+ CheckElementChangeByPlayer(xx, yy, border_element, CE_NEXT_TO_PLAYER,
+ player->index_bit, border_side);
+ CheckTriggeredElementChangeByPlayer(xx, yy, border_element,
+ CE_PLAYER_NEXT_TO_X,
+ player->index_bit, border_side);
+
+ /* use player element that is initially defined in the level playfield,
+ not the player element that corresponds to the runtime player number
+ (example: a level that contains EL_PLAYER_3 as the only player would
+ incorrectly give EL_PLAYER_1 for "player->element_nr") */
+
+ CheckElementChangeBySide(xx, yy, border_element, player->initial_element,
+ CE_NEXT_TO_X, border_side);
+ }
+}
+