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[1.8] Custom entity movement


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I am trying to create a vehicle entity. I am not sure what the best way to do the movement is though. Right now I'm using trigonometry to move it based on its yaw. I am then multiplying it by a speed variable, so that the speed can be controlled:

cart.moveEntity(Math.sin(Math.toRadians(yaw))*-this.speed, 0, Math.cos(Math.toRadians(yaw))*this.speed);

This works great... on singleplayer. For it to work on multiplayer, I started programming packets and setup a Data Watcher to sync the speed variable. I was then thinking, now that all the clients have the speed variable (and of course the yaw as well), the clients should calculate the movement themselves so that there's less lag. I removed the


check so that it would also be run on the client, except that now it's lagging even more. It seems like the problem is that the server still keeps sending position updates to the client. The client receives these a bit later though. The result: The vehicle keeps getting teleported back to where it was a moment ago. -> More Lag!


It would be great if anyone could help me solve this.

Thank you in advance!

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You should provide full code.


As to problem - you need to make sure client and server movement are equal. Most likely they are not, thus lagging. Can't really say more without code.



Btw. why not look at vanilla's rideable?

1.7.10 is no longer supported by forge, you are on your own.

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Entity class:

public abstract class EntityTrainBase extends Entity {

public float speed = 0;
public int connectedTrain = -1;

public EntityTrainBase(World world) {

public void entityInit() {
	this.preventEntitySpawning = false;
	this.setSize(2F, 2F);

	DataWatcher dw = this.getDataWatcher();
	dw.addObject(20, speed);
	dw.addObject(21, connectedTrain);

public abstract double getMountedYOffset();
public abstract float getCartLength();
public abstract float getMaxSpeed();
public abstract boolean isDriver();
public boolean canBeCollidedWith() {
	return true;

public void onEntityUpdate() {
	//if(worldObj.isRemote) {
		if(riddenByEntity != null && riddenByEntity instanceof EntityPlayer) {
			EntityPlayer player = (EntityPlayer) riddenByEntity;
			this.speed = this.getDataWatcher().getWatchableObjectFloat(20) + player.moveForward * .01f;
			this.speed = Math.min(this.speed, this.getMaxSpeed());
			this.speed = Math.max(this.speed, 0);
			this.getDataWatcher().updateObject(20, this.speed);

	moveCart(speed, this);

public void moveCart(float sp, EntityTrainBase cart) {
	if(!(worldObj.getBlockState(cart.getPosition()).getBlock() instanceof BlockRail)) {return;}
	EnumRailDirection rd = (EnumRailDirection) worldObj.getBlockState(cart.getPosition()).getValue(BlockRail.SHAPE);
	float yaw = cart.rotationYaw;

	int y1 = (int) (RailHelper.getYaw1(rd));
	int y2 = (int) (RailHelper.getYaw2(rd));

	if(MathHelper.angleDistance(yaw, y1) < MathHelper.angleDistance(yaw, y2))
		yaw = y1;
		yaw = y2;

	if(riddenByEntity != null && riddenByEntity instanceof EntityPlayer)
		cart.riddenByEntity.rotationYaw += net.minecraft.util.MathHelper.wrapAngleTo180_float(yaw)-cart.rotationYaw;

	cart.rotationYaw = net.minecraft.util.MathHelper.wrapAngleTo180_float(yaw);

	cart.speed = cart.getDataWatcher().getWatchableObjectFloat(20);

	cart.moveEntity(Math.sin(Math.toRadians(yaw))*-cart.speed, 0, Math.cos(Math.toRadians(yaw))*cart.speed);
	//cart.setPositionAndUpdate(cart.posX + Math.sin(Math.toRadians(yaw))*-cart.speed, cart.posY, cart.posZ + Math.cos(Math.toRadians(yaw))*cart.speed);

public boolean interactFirst(EntityPlayer player) {
	if(player.inventory.getCurrentItem() != null && player.inventory.getCurrentItem().isItemEqual(new ItemStack(ModItems.coupler))) {
		((ItemCoupler) ModItems.coupler).interactTrain(player.inventory.getCurrentItem(), player, this);
	} else if(!this.worldObj.isRemote) {
		if(this.riddenByEntity == null || player.ridingEntity == null) {
	return true;


I looked at both the horse and minecart classes and it looks like they use motionX / motionY / motionZ variables. I tried setting those variables instead already but the entity didn't move.

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