Function DrawFoundation

src/landscape.cpp:429–534

* Draw foundation \a f at tile \a ti. Updates \a ti. * @param ti Tile to draw foundation on * @param f Foundation to draw */

 * @param f  Foundation to draw
 */
void DrawFoundation(TileInfo *ti, Foundation f)
{
	if (!IsFoundation(f)) return;

	/* Two part foundations must be drawn separately */
	assert(f != FOUNDATION_STEEP_BOTH);

	uint sprite_block = 0;
	auto [slope, z] = GetFoundationPixelSlope(ti->tile);

	/* Select the needed block of foundations sprites
	 * Block 0: Walls at NW and NE edge
	 * Block 1: Wall  at        NE edge
	 * Block 2: Wall  at NW        edge
	 * Block 3: No walls at NW or NE edge
	 */
	if (!HasFoundationNW(ti->tile, slope, z)) sprite_block += 1;
	if (!HasFoundationNE(ti->tile, slope, z)) sprite_block += 2;

	/* Use the original slope sprites if NW and NE borders should be visible */
	SpriteID leveled_base = (sprite_block == 0 ? (int)SPR_FOUNDATION_BASE : (SPR_SLOPES_VIRTUAL_BASE + sprite_block * TRKFOUND_BLOCK_SIZE));
	SpriteID inclined_base = SPR_SLOPES_VIRTUAL_BASE + SLOPES_INCLINED_OFFSET + sprite_block * TRKFOUND_BLOCK_SIZE;
	SpriteID halftile_base = SPR_HALFTILE_FOUNDATION_BASE + sprite_block * HALFTILE_BLOCK_SIZE;

	if (IsSteepSlope(ti->tileh)) {
		if (!IsNonContinuousFoundation(f)) {
			/* Lower part of foundation */
			static constexpr SpriteBounds bounds{{}, {TILE_SIZE, TILE_SIZE, TILE_HEIGHT - 1}, {}};
			AddSortableSpriteToDraw(leveled_base + (ti->tileh & ~SLOPE_STEEP), PAL_NONE, *ti, bounds);
		}

		Corner highest_corner = GetHighestSlopeCorner(ti->tileh);
		ti->z += ApplyPixelFoundationToSlope(f, ti->tileh);

		if (IsInclinedFoundation(f)) {
			/* inclined foundation */
			uint8_t inclined = highest_corner * 2 + (f == FOUNDATION_INCLINED_Y ? 1 : 0);

			SpriteBounds bounds{{}, {1, 1, TILE_HEIGHT}, {}};
			if (f == FOUNDATION_INCLINED_X) bounds.extent.x = TILE_SIZE;
			if (f == FOUNDATION_INCLINED_Y) bounds.extent.y = TILE_SIZE;
			AddSortableSpriteToDraw(inclined_base + inclined, PAL_NONE, *ti, bounds);
			OffsetGroundSprite(0, 0);
		} else if (IsLeveledFoundation(f)) {
			static constexpr SpriteBounds bounds{{0, 0, -(int)TILE_HEIGHT}, {TILE_SIZE, TILE_SIZE, TILE_HEIGHT - 1}, {}};
			AddSortableSpriteToDraw(leveled_base + SlopeWithOneCornerRaised(highest_corner), PAL_NONE, *ti, bounds);
			OffsetGroundSprite(0, -(int)TILE_HEIGHT);
		} else if (f == FOUNDATION_STEEP_LOWER) {
			/* one corner raised */
			OffsetGroundSprite(0, -(int)TILE_HEIGHT);
		} else {
			/* halftile foundation */
			int8_t x_bb = (((highest_corner == CORNER_W) || (highest_corner == CORNER_S)) ? TILE_SIZE / 2 : 0);
			int8_t y_bb = (((highest_corner == CORNER_S) || (highest_corner == CORNER_E)) ? TILE_SIZE / 2 : 0);

			SpriteBounds bounds{{x_bb, y_bb, TILE_HEIGHT}, {TILE_SIZE / 2, TILE_SIZE / 2, TILE_HEIGHT - 1}, {}};
			AddSortableSpriteToDraw(halftile_base + highest_corner, PAL_NONE, *ti, bounds);
			/* Reposition ground sprite back to original position after bounding box change above. This is similar to