Fix bug with all units' voxels flipped relative to Y axis (OpenXcom#1423

)

* Fix bug with all units' voxels flipped relative Y axis

Center of inverted unit become (7,8) and Volutar deducted that empirically and made dirty fix in commit#757d674 which (fix, not the whole commit) can now be reverted. Big units loftemps loading logic was inverted too, and I've added quick workaround to not break anything

src/Battlescape/TileEngine.cpp

@@ -355,15 +355,15 @@ bool TileEngine::calculateFOV(BattleUnit *unit)
 }
 
 /**
- * Gets the origin voxel of a unit's eyesight (from just one eye or something? Why is it x+7??
+ * Gets the origin voxel of a unit's eyesight
  * @param currentUnit The watcher.
  * @return Approximately an eyeball voxel.
  */
 Position TileEngine::getSightOriginVoxel(BattleUnit *currentUnit)
 {
 	// determine the origin and target voxels for the raytrace
 	Position originVoxel;
-	originVoxel = Position((currentUnit->getPosition().x * 16) + 7, (currentUnit->getPosition().y * 16) + 8, currentUnit->getPosition().z*24);
+	originVoxel = Position((currentUnit->getPosition().x * 16) + 8, (currentUnit->getPosition().y * 16) + 8, currentUnit->getPosition().z*24);
 	originVoxel.z += -_save->getTile(currentUnit->getPosition())->getTerrainLevel();
 	originVoxel.z += currentUnit->getHeight() + currentUnit->getFloatHeight() - 1; //one voxel lower (eye level)
 	Tile *tileAbove = _save->getTile(currentUnit->getPosition() + Position(0,0,1));
@@ -459,7 +459,7 @@ bool TileEngine::visible(BattleUnit *currentUnit, Tile *tile)
  */
 int TileEngine::checkVoxelExposure(Position *originVoxel, Tile *tile, BattleUnit *excludeUnit, BattleUnit *excludeAllBut)
 {
-	Position targetVoxel = Position((tile->getPosition().x * 16) + 7, (tile->getPosition().y * 16) + 8, tile->getPosition().z * 24);
+	Position targetVoxel = Position((tile->getPosition().x * 16) + 8, (tile->getPosition().y * 16) + 8, tile->getPosition().z * 24);
 	Position scanVoxel;
 	std::vector<Position> _trajectory;
 	BattleUnit *otherUnit = tile->getUnit();
@@ -538,7 +538,7 @@ int TileEngine::checkVoxelExposure(Position *originVoxel, Tile *tile, BattleUnit
  */
 bool TileEngine::canTargetUnit(Position *originVoxel, Tile *tile, Position *scanVoxel, BattleUnit *excludeUnit, bool rememberObstacles, BattleUnit *potentialUnit)
 {
-	Position targetVoxel = Position((tile->getPosition().x * 16) + 7, (tile->getPosition().y * 16) + 8, tile->getPosition().z * 24);
+	Position targetVoxel = Position((tile->getPosition().x * 16) + 8, (tile->getPosition().y * 16) + 8, tile->getPosition().z * 24);
 	std::vector<Position> _trajectory;
 	bool hypothetical = potentialUnit != 0;
 	if (potentialUnit == 0)
@@ -2612,13 +2612,14 @@ VoxelType TileEngine::voxelCheck(Position voxel, BattleUnit *excludeUnit, bool e
 			int tz = unitpos.z*24 + unit->getFloatHeight() - terrainHeight; //bottom most voxel, terrain heights are negative, so we subtract.
 			if ((voxel.z > tz) && (voxel.z <= tz + unit->getHeight()) )
 			{
-				int x = voxel.x%16;
+				int x = 15 - voxel.x%16;
 				int y = voxel.y%16;
 				int part = 0;
 				if (unit->getArmor()->getSize() > 1)
 				{
 					tilepos = tile->getPosition();
-					part = tilepos.x - unitpos.x + (tilepos.y - unitpos.y)*2;
+					const static int parts[] = {1,0,3,2}; // Change order 0,1,2,3 -> 1,0,3,2  (read commit description)
+					part = parts[tilepos.x - unitpos.x + (tilepos.y - unitpos.y)*2];
 				}
 				int idx = (unit->getLoftemps(part) * 16) + y;
 				if (_voxelData->at(idx) & (1 << x))