Function getRoadAtCursor

src/OpenLoco/src/Ui/Windows/Vehicle.cpp:4509–4534

0x00478415

        // 0x00478415
        static std::optional<GameCommands::VehiclePlacementArgs> getRoadAtCursor(const int16_t x, const int16_t y)
        {
            auto [interaction, viewport] = ViewportInteraction::getMapCoordinatesFromPos(x, y, ~ViewportInteraction::InteractionItemFlags::roadAndTram);
            if (interaction.type != ViewportInteraction::InteractionItem::road)
            {
                return {};
            }

            // Get the best progress along the road relative to the cursor
            auto* roadElement = static_cast<World::RoadElement*>(interaction.object);
            World::Pos3 loc(interaction.pos.x, interaction.pos.y, roadElement->baseHeight());
            auto progress = getRoadProgressAtCursor({ x, y }, *viewport, *roadElement, loc);

            // Get the coordinates of the first tile of the possibly multi-tile road
            const auto& roadDataArr = World::TrackData::getRoadPiece(roadElement->roadId());
            const auto& roadData = roadDataArr[roadElement->sequenceIndex()];
            auto roadOffset2 = Math::Vector::rotate(World::Pos2(roadData.x, roadData.y), roadElement->rotation());
            auto roadOffset = World::Pos3(roadOffset2.x, roadOffset2.y, roadData.z);
            auto roadFirstTile = loc - roadOffset;

            GameCommands::VehiclePlacementArgs placementArgs;
            placementArgs.pos = roadFirstTile;
            placementArgs.trackProgress = progress;
            placementArgs.trackAndDirection = roadElement->rotation() | (roadElement->roadId() << 3);
            return { placementArgs };
        }

        // 0x00479707
        static std::optional<GameCommands::VehiclePlacementArgs> getVehicleRoadPlacementArgsFromCursor(const Vehicles::VehicleHead& head, const int16_t x, const int16_t y)