Function DrawCustomStationFoundations

src/station_cmd.cpp:3207–3265

* Draw custom station foundations for a NewGRF station if provided. * @param statspec Custom NewGRF station. * @param st Station being drawn. * @param ti Tile being drawn. * @param gfx Graphics layout for tile. * @return true iff a custom foundation was drawn. */

 * @return true iff a custom foundation was drawn.
 */
static bool DrawCustomStationFoundations(const StationSpec *statspec, BaseStation *st, TileInfo *ti, StationGfx gfx)
{
	if (statspec == nullptr || !statspec->flags.Test(StationSpecFlag::CustomFoundations)) return false;

	/* Station has custom foundations.
	 * Check whether the foundation continues beyond the tile's upper sides. */
	uint edge_info = 0;
	auto [slope, z] = GetFoundationPixelSlope(ti->tile);
	if (!HasFoundationNW(ti->tile, slope, z)) SetBit(edge_info, 0);
	if (!HasFoundationNE(ti->tile, slope, z)) SetBit(edge_info, 1);

	SpriteID image = GetCustomStationFoundationRelocation(statspec, st, ti->tile, gfx, edge_info);
	if (image == 0) return false;

	if (statspec->flags.Test(StationSpecFlag::ExtendedFoundations)) {
		/* Station provides extended foundations. */
		static constexpr uint8_t foundation_parts[] = {
			UINT8_MAX, UINT8_MAX, UINT8_MAX,         0, // Invalid,  Invalid,   Invalid,   SLOPE_SW
			UINT8_MAX,         1,         2,         3, // Invalid,  SLOPE_EW,  SLOPE_SE,  SLOPE_WSE
			UINT8_MAX,         4,         5,         6, // Invalid,  SLOPE_NW,  SLOPE_NS,  SLOPE_NWS
			        7,         8,         9,            // SLOPE_NE, SLOPE_ENW, SLOPE_SEN
		};
		assert(ti->tileh < std::size(foundation_parts));
		if (foundation_parts[ti->tileh] == UINT8_MAX) return false;

		AddSortableSpriteToDraw(image + foundation_parts[ti->tileh], PAL_NONE, *ti, {{}, {TILE_SIZE, TILE_SIZE, TILE_HEIGHT - 1}, {}});
	} else {
		/* Draw simple foundations, built up from 8 possible foundation sprites.
		 * Each set bit represents one of the eight composite sprites to be drawn.
		 * 'Invalid' entries will not drawn but are included for completeness. */
		static constexpr uint8_t composite_foundation_parts[] = {
			0b0000'0000, 0b1101'0001, 0b1110'0100, 0b1110'0000, // Invalid,  Invalid,   Invalid,   SLOPE_SW
			0b1100'1010, 0b1100'1001, 0b1100'0100, 0b1100'0000, // Invalid,  SLOPE_EW,  SLOPE_SE,  SLOPE_WSE
			0b1101'0010, 0b1001'0001, 0b1110'0100, 0b1010'0000, // Invalid,  SLOPE_NW,  SLOPE_NS,  SLOPE_NWS
			0b0100'1010, 0b0000'1001, 0b0100'0100,              // SLOPE_NE, SLOPE_ENW, SLOPE_SEN
		};
		assert(ti->tileh < std::size(composite_foundation_parts));

		uint8_t parts = composite_foundation_parts[ti->tileh];

		/* If foundations continue beyond the tile's upper sides then mask out the last two pieces. */
		if (HasBit(edge_info, 0)) ClrBit(parts, 6);
		if (HasBit(edge_info, 1)) ClrBit(parts, 7);

		/* We always have to draw at least one sprite, so if we have no parts to draw fall back to default foundation. */
		if (parts == 0) return false;

		StartSpriteCombine();
		for (uint i : SetBitIterator(parts)) {
			AddSortableSpriteToDraw(image + i, PAL_NONE, *ti, {{}, {TILE_SIZE, TILE_SIZE, TILE_HEIGHT - 1}, {}});
		}
		EndSpriteCombine();
	}

	OffsetGroundSprite(0, -static_cast<int>(TILE_HEIGHT));
	ti->z += ApplyPixelFoundationToSlope(FOUNDATION_LEVELED, ti->tileh);

	return true;