Function ViewportAddVehicles

src/vehicle.cpp:1121–1206

* Add the vehicle sprites that should be drawn at a part of the screen. * @param dpi Rectangle being drawn. */

 * @param dpi Rectangle being drawn.
 */
void ViewportAddVehicles(DrawPixelInfo *dpi)
{
	/* The bounding rectangle */
	const int l = dpi->left;
	const int r = dpi->left + dpi->width;
	const int t = dpi->top;
	const int b = dpi->top + dpi->height;

	/* Border size of MAX_VEHICLE_PIXEL_xy */
	const int xb = MAX_VEHICLE_PIXEL_X * ZOOM_BASE;
	const int yb = MAX_VEHICLE_PIXEL_Y * ZOOM_BASE;

	/* The hash area to scan */
	uint xl, xu, yl, yu;

	if (static_cast<uint>(dpi->width + xb) < GEN_HASHX_SIZE) {
		xl = GetViewportHashX(l - xb);
		xu = GetViewportHashX(r);
	} else {
		/* scan whole hash row */
		xl = 0;
		xu = GEN_HASHX_MASK;
	}

	if (static_cast<uint>(dpi->height + yb) < GEN_HASHY_SIZE) {
		yl = GetViewportHashY(t - yb);
		yu = GetViewportHashY(b);
	} else {
		/* scan whole column */
		yl = 0;
		yu = GEN_HASHY_MASK;
	}

	for (uint y = yl;; y = (y + GEN_HASHY_INC) & GEN_HASHY_MASK) {
		for (uint x = xl;; x = (x + GEN_HASHX_INC) & GEN_HASHX_MASK) {
			const Vehicle *v = _vehicle_viewport_hash[x + y]; // already masked & 0xFFF

			while (v != nullptr) {

				if (!v->vehstatus.Test(VehState::Hidden) &&
					l <= v->coord.right + xb &&
					t <= v->coord.bottom + yb &&
					r >= v->coord.left - xb &&
					b >= v->coord.top - yb)
				{
					/*
					 * This vehicle can potentially be drawn as part of this viewport and
					 * needs to be revalidated, as the sprite may not be correct.
					 */
					if (v->sprite_cache.revalidate_before_draw) {
						VehicleSpriteSeq seq;
						v->GetImage(v->direction, EIT_ON_MAP, &seq);

						if (seq.IsValid() && v->sprite_cache.sprite_seq != seq) {
							v->sprite_cache.sprite_seq = seq;
							/*
							 * A sprite change may also result in a bounding box change,
							 * so we need to update the bounding box again before we