Function CheckBridgeSlope

src/tunnelbridge_cmd.cpp:213–231

* Determines the foundation for the bridge head, and tests if the resulting slope is valid. * * @param bridge_piece Direction of the bridge head. * @param axis Axis of the bridge * @param tileh Slope of the tile under the north bridge head; returns slope on top of foundation * @param z TileZ corresponding to tileh, gets modified as well * @return Error or cost for bridge foundation */

 * @return Error or cost for bridge foundation
 */
static CommandCost CheckBridgeSlope(BridgePieces bridge_piece, Axis axis, Slope &tileh, int &z)
{
	assert(bridge_piece == BRIDGE_PIECE_NORTH || bridge_piece == BRIDGE_PIECE_SOUTH);

	Foundation f = GetBridgeFoundation(tileh, axis);
	z += ApplyFoundationToSlope(f, tileh);

	Slope valid_inclined;
	if (bridge_piece == BRIDGE_PIECE_NORTH) {
		valid_inclined = (axis == AXIS_X ? SLOPE_NE : SLOPE_NW);
	} else {
		valid_inclined = (axis == AXIS_X ? SLOPE_SW : SLOPE_SE);
	}
	if ((tileh != SLOPE_FLAT) && (tileh != valid_inclined)) return CMD_ERROR;

	if (f == FOUNDATION_NONE) return CommandCost();

	return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
}

/**
 * Is a bridge of the specified type and length available?