Method UpdateVisualEffect

src/vehicle.cpp:2636–2694

* Update the cached visual effect. * @param allow_power_change true if the wagon-is-powered-state may change. */

 * @param allow_power_change true if the wagon-is-powered-state may change.
 */
void Vehicle::UpdateVisualEffect(bool allow_power_change)
{
	bool powered_before = HasBit(this->vcache.cached_vis_effect, VE_DISABLE_WAGON_POWER);
	const Engine *e = this->GetEngine();

	/* Evaluate properties */
	uint8_t visual_effect;
	switch (e->type) {
		case VEH_TRAIN: visual_effect = e->VehInfo<RailVehicleInfo>().visual_effect; break;
		case VEH_ROAD:  visual_effect = e->VehInfo<RoadVehicleInfo>().visual_effect; break;
		case VEH_SHIP:  visual_effect = e->VehInfo<ShipVehicleInfo>().visual_effect; break;
		default:        visual_effect = 1 << VE_DISABLE_EFFECT;  break;
	}

	/* Check powered wagon / visual effect callback */
	if (e->info.callback_mask.Test(VehicleCallbackMask::VisualEffect)) {
		uint16_t callback = GetVehicleCallback(CBID_VEHICLE_VISUAL_EFFECT, 0, 0, this->engine_type, this);

		if (callback != CALLBACK_FAILED) {
			if (callback >= 0x100 && e->GetGRF()->grf_version >= 8) ErrorUnknownCallbackResult(e->GetGRFID(), CBID_VEHICLE_VISUAL_EFFECT, callback);

			callback = GB(callback, 0, 8);
			/* Avoid accidentally setting 'visual_effect' to the default value
			 * Since bit 6 (disable effects) is set anyways, we can safely erase some bits. */
			if (callback == VE_DEFAULT) {
				assert(HasBit(callback, VE_DISABLE_EFFECT));
				SB(callback, VE_TYPE_START, VE_TYPE_COUNT, 0);
			}
			visual_effect = callback;
		}
	}

	/* Apply default values */
	if (visual_effect == VE_DEFAULT ||
			(!HasBit(visual_effect, VE_DISABLE_EFFECT) && GB(visual_effect, VE_TYPE_START, VE_TYPE_COUNT) == VE_TYPE_DEFAULT)) {
		/* Only train engines have default effects.
		 * Note: This is independent of whether the engine is a front engine or articulated part or whatever. */
		if (e->type != VEH_TRAIN || e->VehInfo<RailVehicleInfo>().railveh_type == RAILVEH_WAGON || !IsInsideMM(e->VehInfo<RailVehicleInfo>().engclass, EC_STEAM, EC_MONORAIL)) {
			if (visual_effect == VE_DEFAULT) {
				visual_effect = 1 << VE_DISABLE_EFFECT;
			} else {
				SetBit(visual_effect, VE_DISABLE_EFFECT);
			}
		} else {
			if (visual_effect == VE_DEFAULT) {
				/* Also set the offset */
				visual_effect = (VE_OFFSET_CENTRE - (e->VehInfo<RailVehicleInfo>().engclass == EC_STEAM ? 4 : 0)) << VE_OFFSET_START;
			}
			SB(visual_effect, VE_TYPE_START, VE_TYPE_COUNT, e->VehInfo<RailVehicleInfo>().engclass - EC_STEAM + VE_TYPE_STEAM);
		}
	}

	this->vcache.cached_vis_effect = visual_effect;

	if (!allow_power_change && powered_before != HasBit(this->vcache.cached_vis_effect, VE_DISABLE_WAGON_POWER)) {
		ToggleBit(this->vcache.cached_vis_effect, VE_DISABLE_WAGON_POWER);
		ShowNewGrfVehicleError(this->engine_type, STR_NEWGRF_BROKEN, STR_NEWGRF_BROKEN_POWERED_WAGON, GRFBug::VehPoweredWagon, false);
	}