Method UpdateDeltaXY

src/train_cmd.cpp:1493–1554

}

void Train::UpdateDeltaXY()
{
	/* Set common defaults. */
	this->bounds = {{-1, -1, 0}, {3, 3, 6}, {}};

	/* Set if flipped and engine is NOT flagged with custom flip handling. */
	int flipped = this->flags.Test(VehicleRailFlag::Flipped) && !EngInfo(this->engine_type)->misc_flags.Test(EngineMiscFlag::RailFlips);
	/* If flipped and vehicle length is odd, we need to adjust the bounding box offset slightly. */
	int flip_offs = flipped && (this->gcache.cached_veh_length & 1);

	Direction dir = this->direction;
	if (flipped) dir = ReverseDir(dir);

	if (!IsDiagonalDirection(dir)) {
		static const Point _sign_table[] = {
			/* x, y */
			{-1, -1}, // DIR_N
			{-1,  1}, // DIR_E
			{ 1,  1}, // DIR_S
			{ 1, -1}, // DIR_W
		};

		int half_shorten = (VEHICLE_LENGTH - this->gcache.cached_veh_length + flipped) / 2;

		/* For all straight directions, move the bound box to the centre of the vehicle, but keep the size. */
		this->bounds.offset.x -= half_shorten * _sign_table[DirToDiagDir(dir)].x;
		this->bounds.offset.y -= half_shorten * _sign_table[DirToDiagDir(dir)].y;
	} else {
		switch (dir) {
				/* Shorten southern corner of the bounding box according the vehicle length
				 * and center the bounding box on the vehicle. */
			case DIR_NE:
				this->bounds.origin.x = -(this->gcache.cached_veh_length + 1) / 2 + flip_offs;
				this->bounds.extent.x = this->gcache.cached_veh_length;
				this->bounds.offset.x = 1;
				break;

			case DIR_NW:
				this->bounds.origin.y = -(this->gcache.cached_veh_length + 1) / 2 + flip_offs;
				this->bounds.extent.y = this->gcache.cached_veh_length;
				this->bounds.offset.y = 1;
				break;

				/* Move northern corner of the bounding box down according to vehicle length
				 * and center the bounding box on the vehicle. */
			case DIR_SW:
				this->bounds.origin.x = -(this->gcache.cached_veh_length) / 2 - flip_offs;
				this->bounds.extent.x = this->gcache.cached_veh_length;
				this->bounds.offset.x = 1 - (VEHICLE_LENGTH - this->gcache.cached_veh_length);
				break;

			case DIR_SE:
				this->bounds.origin.y = -(this->gcache.cached_veh_length) / 2 - flip_offs;
				this->bounds.extent.y = this->gcache.cached_veh_length;
				this->bounds.offset.y = 1 - (VEHICLE_LENGTH - this->gcache.cached_veh_length);
				break;

			default: