I'm trying to simulate wind during rain in my mod. So I have a tick handler that's listening for the ServerTickEvent, and after a cooldown, it checks the world for rain, then iterates through all loaded entities and adds to their velocity. Sounds simple, right?

 

Except it's not doing anything. I put a debug message into the console logger to see what's going on, but the message looks fine: it tells me it's moving me with a random x or z amount between 1 and 4, just as it should be. But I don't actually move...nothing moves. Am I using the Entity#addVelocity() function incorrectly or something?

 

This is the code for the tick handler:

 

package com.IceMetalPunk.weatherworks;

import java.util.List;

import cpw.mods.fml.common.eventhandler.EventBus;
import cpw.mods.fml.common.eventhandler.SubscribeEvent;
import cpw.mods.fml.common.gameevent.TickEvent.Phase;
import cpw.mods.fml.common.gameevent.TickEvent.ServerTickEvent;
import net.minecraft.client.Minecraft;
import net.minecraft.entity.Entity;
import net.minecraft.entity.player.EntityPlayerMP;
import net.minecraft.server.MinecraftServer;
import net.minecraft.world.World;

public class WeatherTickHandler {
private byte dir=0;
private float amt=1.0f;
private int cooldown=0;

public WeatherTickHandler(EventBus bus) {
	bus.register(this);;
}

@SubscribeEvent
public void onTick(ServerTickEvent event) {
	if (event.phase==Phase.START) {

		// Decrement the cooldown
		if (this.cooldown>0) { --this.cooldown; }

		// Only blow wind when cooldown<=40
		if (this.cooldown>40) { return; }

		World world=MinecraftServer.getServer().getEntityWorld();

		// Only blow wind when it's raining
		if (world.getWorldInfo().isRaining() || world.getWorldInfo().isThundering()) {

			// Calculate wind speed on x and z axes
			float velX=(this.dir==0)?this.amt:((this.dir==1)?-this.amt:0);
			float velZ=(this.dir==2)?this.amt:((this.dir==3)?-this.amt:0);

			// Iterate through the list of entities
			List entities=world.getLoadedEntityList();
			for (int p=0; p<entities.size(); ++p) {
				Entity ent=((Entity)entities.get(p));

				/* Debug message */
				if (ent instanceof EntityPlayerMP) {
					System.out.println("Moving "+ent+" by "+velX+", "+velZ);
				}
				/* End debug message */

				// Add the velocity to each entity
				ent.addVelocity(velX, 0.0d, velZ);
			}
		}

		// When cooldown=0, reset cooldown and choose a random direction and amount for next time
		if (this.cooldown==0) {
			this.cooldown=100;
			this.dir=(byte)world.rand.nextInt(4);
			this.amt=world.rand.nextFloat()*3.0f+1.0f;
		}
	}
}
}

Just edit the motionXYZ values directly

Do non-player entities move correctly? Players are a bit 'special', in that their motion is determined almost entirely client-side - you need to send a packet to the client telling it what is new motion should be.

Have you played with the scale of your wind velocity to calibrate it? Maybe you're adding a trivial amount.

 

If you keep adding velocity to already moving entities, won't they accelerate to great speeds?

 

And what will happen to minecarts? Paintings (and itemFrames)?

@thebest108: I tried that first, and it didn't work, either.

 

@jeffryfisher: I figured I'd deal with the special cases of "static" entities once I got the main system working. 4 blocks per second per second is certainly not trivial But they are, in fact, supposed to accelerate. Keep in mind it only happens for a short period of time each "gust" of wind, it's not constantly accelerating them.

 

@coolAlias: Aha! When it didn't work for the player, I kept trying to fix it without thinking to test other entities. It actually does work for other entities (I had to lower the amounts and timings to get something decent, but that's trivial). I didn't realize player motion was entirely client-side. I guess I'll have to implement a packet handler for this, then. I'll try that and see where it goes from there. Thanks!

 

*EDIT* Well...that made things worse. Now, when the wind starts, the game just locks up completely. The debug output tells me that, for some odd reason, even though the packet message instance is created with the proper x, y, and z velocity values, by the time the client receives it, it's reading ridiculously large (as in, on the order of 1E9) x and y values instead. I can't figure out why.

 

Here's the updated tick handler source:

package com.IceMetalPunk.weatherworks;

import java.util.List;

import cpw.mods.fml.common.eventhandler.EventBus;
import cpw.mods.fml.common.eventhandler.SubscribeEvent;
import cpw.mods.fml.common.gameevent.TickEvent.Phase;
import cpw.mods.fml.common.gameevent.TickEvent.ServerTickEvent;
import net.minecraft.client.Minecraft;
import net.minecraft.entity.Entity;
import net.minecraft.entity.player.EntityPlayerMP;
import net.minecraft.server.MinecraftServer;
import net.minecraft.world.World;

public class WeatherTickHandler {
private byte dir=0;
private float amt=1.0f;
private int cooldown=0;
private final double threshold=20.0d;

public WeatherTickHandler(EventBus bus) {
	bus.register(this);;
}

@SubscribeEvent
public void onTick(ServerTickEvent event) {
	if (event.phase==Phase.START) {

		// Decrement the cooldown
		if (this.cooldown>0) { --this.cooldown; }

		// Only blow wind when cooldown<=40
		if (this.cooldown>this.threshold) { return; }

		World world=MinecraftServer.getServer().getEntityWorld();

		// Only blow wind when it's raining
		if (world.getWorldInfo().isRaining() || world.getWorldInfo().isThundering()) {

			// Calculate wind speed on x and z axes
			float velX=(this.dir==0)?this.amt:((this.dir==1)?-this.amt:0);
			float velZ=(this.dir==2)?this.amt:((this.dir==3)?-this.amt:0);

			// Iterate through the list of entities
			List entities=world.getLoadedEntityList();
			for (int p=0; p<entities.size(); ++p) {
				Entity ent=((Entity)entities.get(p));

				/* Debug message */
				if (ent instanceof EntityPlayerMP && this.cooldown==this.threshold) {
					System.out.println("Sending "+((double)(velX*this.threshold))+", "+(0.0d)+", "+((double)(velZ*this.threshold)));
					WeatherworksPacketHandler.INSTANCE.sendToAll(new WeatherManipMessage((byte)2, (double)(velX*this.threshold), 0.0d, (double)(velZ*this.threshold), (byte)0));
				}
				/* End debug message */

				// Add the velocity to each entity
				ent.addVelocity((double)velX, 0.0d, (double)velZ);
			}
		}

		// When cooldown=0, reset cooldown and choose a random direction and amount for next time
		if (this.cooldown==0) {
			this.cooldown=100;
			this.dir=(byte)world.rand.nextInt(4);
			this.amt=world.rand.nextFloat()/4.0f;
		}
	}
}
}

 

Here's the message class ("val" is there for other message types; it's irrelevant to this issue):

public class WeatherManipMessage implements IMessage {

public byte val=0;
public double x, y, z;
public byte messageType=0;

public WeatherManipMessage() {};

public WeatherManipMessage(byte type, double x, double y, double z, byte state) {
	this.val=state;
	this.x=x;
	this.y=y;
	this.z=z;
	this.messageType=type;
	System.out.println("Created message with "+this.x+", "+this.y+", "+this.z);
}

@Override
public void fromBytes(ByteBuf buf) {
	this.messageType=buf.readByte();
	this.x=buf.readInt();
	this.y=buf.readInt();
	this.z=buf.readInt();
	this.val=buf.readByte();
}

@Override
public void toBytes(ByteBuf buf) {
	buf.writeByte(this.messageType);
	buf.writeDouble(this.x);
	buf.writeDouble(this.y);
	buf.writeDouble(this.z);
	buf.writeByte(this.val);
}
}

 

Here's the message handler:

public static class WeatherWorksWindHandler implements IMessageHandler<WeatherManipMessage,IMessage> {

	@Override
	public IMessage onMessage(WeatherManipMessage message, MessageContext ctx) {
		if (message.messageType==2) {
			EntityPlayer player=Minecraft.getMinecraft().thePlayer;
			System.out.println("Moved "+player+" by "+(message.x)+", "+(message.y)+", "+(message.z));
			player.addVelocity(message.x, message.y, message.z);
		}
		return null;
	}

}

 

And here's the registration of the message handler, in the preinit event handler:

int messageID=0;
WeatherworksPacketHandler.INSTANCE.registerMessage(WeatherWorksWindHandler.class, WeatherManipMessage.class, messageID++, Side.CLIENT);

 

Given that, this is the strange output I'm getting in the console:

[15:47:14] [server thread/INFO] [sTDOUT]: [com.IceMetalPunk.weatherworks.WeatherTickHandler:onTick:51]: Sending 0.611920952796936, 0.0, 0.0
[15:47:14] [server thread/INFO] [sTDOUT]: [com.IceMetalPunk.weatherworks.WeatherManipMessage:<init>:26]: Created message with 0.611920952796936, 0.0, 0.0
[15:47:14] [Client thread/INFO] [sTDOUT]: [com.IceMetalPunk.weatherworks.WeatherManipMessage$WeatherWorksWindHandler:onMessage:84]: Moved EntityClientPlayerMP['Player703'/7, l='MpServer', x=582.96, y=57.62, z=-124.47] by 1.071879387E9, 1.073741824E9, 0.0

 

As you can see, the values it's sending are fine, the constructor is setting those values fine as well...but when the client receives the message, it's reading massive and incorrect values instead. I can't figure out why?

https://github.com/Dragonisser/CobaltMod/blob/master/src/main/java/cobaltmod/entity/EntityCobaltGuardian.java#L375

 

You probably need to add this: entityplayer.velocityChanged = true;

https://github.com/Dragonisser/CobaltMod/blob/master/src/main/java/cobaltmod/entity/EntityCobaltGuardian.java#L375

 

You probably need to add this: entityplayer.velocityChanged = true;

Gah! That worked! All this trouble with the packet handling, and it wasn't even necessary after all >_< Thank you so much!

https://github.com/Dragonisser/CobaltMod/blob/master/src/main/java/cobaltmod/entity/EntityCobaltGuardian.java#L375

 

You probably need to add this: entityplayer.velocityChanged = true;

Gah! That worked! All this trouble with the packet handling, and it wasn't even necessary after all >_< Thank you so much!

 

No problem ^^