Function DrawBridgePillars

src/tunnelbridge_cmd.cpp:1098–1143

* Draws the pillars under high bridges. * * @param psid Image and palette of a bridge pillar. * @param ti #TileInfo of current bridge-middle-tile. * @param axis Orientation of bridge. * @param drawfarpillar Whether to draw the pillar at the back * @param x Sprite X position of front pillar. * @param y Sprite Y position of front pillar. * @param z_bridge Absolute height of bridge bottom. *

 * @param z_bridge Absolute height of bridge bottom.
 */
static void DrawBridgePillars(const PalSpriteID &psid, const TileInfo *ti, Axis axis, bool drawfarpillar, int x, int y, int z_bridge)
{
	static const int bounding_box_size[2]  = {16, 2}; ///< bounding box size of pillars along bridge direction
	static const int back_pillar_offset[2] = { 0, 9}; ///< sprite position offset of back facing pillar

	static const int INF = 1000; ///< big number compared to sprite size
	static const SubSprite half_pillar_sub_sprite[2][2] = {
		{ {  -14, -INF, INF, INF }, { -INF, -INF, -15, INF } }, // X axis, north and south
		{ { -INF, -INF,  15, INF }, {   16, -INF, INF, INF } }, // Y axis, north and south
	};

	if (psid.sprite == 0) return;

	/* Determine ground height under pillars */
	DiagDirection south_dir = AxisToDiagDir(axis);
	int z_front_north = ti->z;
	int z_back_north = ti->z;
	int z_front_south = ti->z;
	int z_back_south = ti->z;
	GetSlopePixelZOnEdge(ti->tileh, south_dir, z_front_south, z_back_south);
	GetSlopePixelZOnEdge(ti->tileh, ReverseDiagDir(south_dir), z_front_north, z_back_north);

	/* Shared height of pillars */
	int z_front = std::max(z_front_north, z_front_south);
	int z_back = std::max(z_back_north, z_back_south);

	/* x and y size of bounding-box of pillars */
	int w = bounding_box_size[axis];
	int h = bounding_box_size[OtherAxis(axis)];
	/* sprite position of back facing pillar */
	int x_back = x - back_pillar_offset[axis];
	int y_back = y - back_pillar_offset[OtherAxis(axis)];

	/* Draw front pillars */
	int bottom_z = DrawPillarColumn(z_front, z_bridge, psid, x, y, w, h);
	if (z_front_north < z_front) DrawPillar(psid, x, y, bottom_z, w, h, &half_pillar_sub_sprite[axis][0]);
	if (z_front_south < z_front) DrawPillar(psid, x, y, bottom_z, w, h, &half_pillar_sub_sprite[axis][1]);

	/* Draw back pillars, skip top two parts, which are hidden by the bridge */
	int z_bridge_back = z_bridge - 2 * (int)TILE_HEIGHT;
	if (drawfarpillar && (z_back_north <= z_bridge_back || z_back_south <= z_bridge_back)) {
		bottom_z = DrawPillarColumn(z_back, z_bridge_back, psid, x_back, y_back, w, h);
		if (z_back_north < z_back) DrawPillar(psid, x_back, y_back, bottom_z, w, h, &half_pillar_sub_sprite[axis][0]);
		if (z_back_south < z_back) DrawPillar(psid, x_back, y_back, bottom_z, w, h, &half_pillar_sub_sprite[axis][1]);
	}
}

/**
 * Retrieve the sprites required for catenary on a road/tram bridge.