How to create the swirly particle potion effect

I spent a couple hours today trying to figure out how to force a player to see the potion effect on another entity (that swirly particle effect that appears when you drink a potion). I finally figured it out, so I thought I'd share.

Code:java

 
protected void playPotionEffect(final Player player, final LivingEntity entity, int color, int duration) {
final DataWatcher dw = new DataWatcher();
dw.a(8, Integer.valueOf(0));
dw.watch(8, Integer.valueOf(color));
 
Packet40EntityMetadata packet = new Packet40EntityMetadata(entity.getEntityId(), dw);
((CraftPlayer)player).getHandle().netServerHandler.sendPacket(packet);
 
Bukkit.getScheduler().scheduleSyncDelayedTask(plugin, new Runnable() {
public void run() {
DataWatcher dwReal = ((CraftLivingEntity)entity).getHandle().getDataWatcher();
dw.watch(8, dwReal.getInt(8));
Packet40EntityMetadata packet = new Packet40EntityMetadata(entity.getEntityId(), dw);
((CraftPlayer)player).getHandle().netServerHandler.sendPacket(packet);
}
}, duration);
}
 

The effect will only show up for the player provided, and it will show up on the entity you specify. The color is a standard hex color, and the duration is in ticks. For example:

Code:java

 
playPotionEffect(player, entity, 0x0000FF, 40);
 

That would show a blue potion swirl effect on the entity for two seconds.

Update 5/2/2012:

A bit after creating this, I modified it a bit (after reading the comments) so that it would be displayed for everyone nearby.

Code:java

 
    public void addPotionGraphicalEffect(LivingEntity entity, int color, int duration) {
        final EntityLiving el = ((CraftLivingEntity)entity).getHandle();
        final DataWatcher dw = el.getDataWatcher();
        dw.watch(8, Integer.valueOf(color));
 
        Bukkit.getScheduler().scheduleSyncDelayedTask(plugin, new Runnable() {
            public void run() {
                int c = 0;
                if (!el.effects.isEmpty()) {
                    c = net.minecraft.server.PotionBrewer.a(el.effects.values());
                }
                dw.watch(8, Integer.valueOf(c));
            }
        }, duration);
    }
 

 

Thanks.

 

You are amazing, tons of uses for this. Will come in handy when I finish my dungeon plugin, great for highlighting loot.

 

This has potential, Bukkit should really implement wrapper functions around Packet40EntityMetadata.

Btw: Packet40Metadata simply transfer the 'datawatcher' data set for the entity. Using this packet it is also possible to make minecarts smoke. (it's the first time I encountered it)

If you don't want to send packets, you can set the data of the DataWatcher object (entity.getDataWatcher()). The entity tracker will automatically send a meta data packet to all nearby players. (including self)

 

code please I really hate that part of the classes...

 

Basically this:

((CraftLivingEntity)entity).getHandle().getDataWatcher().watch(int, Object);

 

ah thanks... hmm and to keep the effect going I probably have to use a scheduler...

 

I believe it should actually stay until it's overwritten by another effect (like if the player drinks a potion that causes a new effect).

 

ahh... that would be cool... I want to use that with an afk plugin.. when I ever get that time

 

Is it safe to assume that this can't be used to play the particle effect at any given location, and only at that of an entity?

 

Right. It uses entity metadata.

 

nisovin
You don't happen to know portal effects do you?
I skimmed the post, this sort of stuff is new to me.

 

Nice work nisovin I will add this to my spells plugin, any chance of more EPIC effects? maybe something mixed with DrBowe 's rocket physics

 

thehutch
That was one of the first things I was curious about, but in order to do that, there'd need to be an entity for the effect to latch onto. It may be possible by faking entities at each location, but it'll eventually become more hacky than it's worth. (If it's possible at all, for that matter)

 

I can't figure out how to send the sit(or ride an entity) packet with nisovin 's method. The index is 2 and the Bit mask is 0x04. This page gives some info about the metadata.
Imma tag everyone xD
bergerkiller
DrBowe




So far, not so good:

Code:

    public static void playerSitPacketSender(CraftLivingEntity player) {
   
        DataWatcher dw = new DataWatcher();
        dw.watch(player.getEntityId(), Integer.valueOf(0x04));
        dw.a(2, Integer.valueOf(0));
   
        new Packet40EntityMetadata();
        Packet40EntityMetadata sitPacket = new Packet40EntityMetadata(player.getEntityId(), dw);
   
        player.getHandle().getDataWatcher().watch(2, sitPacket);

 

heisan213 not like that
Do it like this:

Code:

player.getHandle().datawatcher.a(2, 0);
OR:
player.getHandle().getDataWatcher().a(2, 0);

And that's IT. No packets are needed at all; that is done by the entity tracker, which listens for meta data changes on the entity directly.

Though, I am not sure what the 2 and 0 denote, you'll have to look at the native source code for a bit. (or look at the potion source code)

 

<3 Thanks (giving like) I'll poke around some more Spendt hours yesterday scanning MC server source...

I think I have to trick the client into believing it is in a minecart or something to make the effect appear. The code runs without errors at least

 

Hmmm, isn't there an easier way to do this now with the new Potions API?

 

Yes, if you want the actual potion effect applied as well. This is for if you want to apply the particle effect without the potion effect.

 

nisovin
@bergerkiller
Ok so I had a little attepmt at combining your code with DrBowe and came up with this but I am having some trouble creating a fake entity any ideas on how to do it? I know Packet24MobSpawn is used to spawn a mob but giving it a fake value I couldn't think of
Here is what I have but it probably is just a joke atm :

Code:java

 
public class ArcaneEffect implements Runnable{
 
private Location startLoc;
private Location endLoc;
private ArrayList<ParticleData> locationsForProjection;
private double turningPoint;
private World world;
private iSpells plugin;
private double radius;
private float effectThickness;
private int i;
 
 
public ArcaneEffect(iSpells instance,Location loc1, Location loc2, double turningPoint, float effectThickness, double radius) {
this.locationsForProjection = calculateLocsForProjections();
this.effectThickness = effectThickness;
this.turningPoint = turningPoint;
this.world = loc1.getWorld();
this.plugin = instance;
this.radius = radius;
this.startLoc = loc1;
this.endLoc = loc2;
this.i = 0;
}
 
@Override
public void run() {
if (i > locationsForProjection.size()-1) {
return;
}
final ParticleData data = locationsForProjection.get(i);
if (!data.isPastTurningPoint()) {
final DataWatcher dw = new DataWatcher();
dw.a(8, Integer.valueOf(0));
//dw.watch(8, Integer.valueOf(10));
for (int x=0 ; x<effectThickness ; x++) {
final Packet24MobSpawn packet = new Packet24MobSpawn();
for(Player p : data.getLocation().getWorld().getPlayers()) {
((CraftPlayer)p).getHandle().netServerHandler.sendPacket(packet);
}
Bukkit.getScheduler().scheduleSyncDelayedTask(plugin, new Runnable() {
@Override
public void run() {
// temp variables
CraftServer cs = null; // <== are null
EntityLiving el = null; // <==
DataWatcher dwReal = new CraftLivingEntity(cs, el).getHandle().getDataWatcher();
dw.watch(8, dwReal.getInt(8));
for(Player p : data.getLocation().getWorld().getPlayers()) {
((CraftPlayer)p).getHandle().netServerHandler.sendPacket(packet);
 
}
}, i);
}
i++;
} else {
if (data.getLocation() == endLoc) {
Block centre = world.getBlockAt(endLoc);
double accuracy = 0.1 * Math.PI;
int dx, dz;
for(double d=0 ; d<Math.PI*2 ; d+=accuracy) {
dx = (int) (radius * Math.cos(d));
dz = (int) (radius * Math.sin(d));
if (centre.getRelative(dx, 1, dz).getType() == Material.AIR) {
centre.getRelative(dx, 1, dz).setType(Material.FIRE);
}
}
}
}
}
 
private ArrayList<ParticleData> calculateLocsForProjections() {
double distance = startLoc.distance(endLoc);
double x1,y1,z1,x2,y2,z2,xVect,yVect,zVect;
 
x1 = endLoc.getX();
y1 = endLoc.getY();
z1 = endLoc.getZ();
 
x2 = endLoc.getX();
y2 = endLoc.getY();
z2 = endLoc.getZ();
 
xVect = x2-x1;
yVect = y2-y1;
zVect = z2-z1;
 
ArrayList<ParticleData> tmp = new ArrayList<ParticleData>((int)Math.floor(distance));
for(double t=0 ; t<=1 ; t+= 1/distance) {
tmp.add(new ParticleData(new Location(world, x2-(xVect*t) , y2-(yVect*t) , z2-(zVect*t)), t>turningPoint));
}
return tmp;
}
}
 

iPhysX Do you know of anyway to create this fake entity? You must be good with PhysiX's right

Ok I added this bit awell to replace the craftServer, although I still need an Entityliving

Code:

CraftServer cs = (CraftServer)plugin.getServer();

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

Ok, didn't realise that.

 

sorry thehutch if i had some info, or i knew how to achieve it, I would help out. But I'm not good for any of this stuff. Sorry!
I'm watching the thread though, so if there is a breakthrough, I can learn.

 

Ok so I decided to attach this to an arrow because it is much easier here is the code so far:
http://pastie.org/3381351

If bergerkiller , nisovin , DrBowe see any improvements or fixes please tell me

 

thehutch you should post a screeny of the effect? It works i assume?

 

iPhysX Unfortunately it isn't working atm for some reason I am trying to make a fix

 

I actually can't figure out how to trick the client into beliving there is a minecart under the player that I want to add the sitting effect to... Any ideas bergerkiller ?
nisovin ?

 

heisan213 I've been looking into this as well. It is possible, but replicating it is pretty hard. You need to make the client believe he is sitting in a destroyed minecart. (you can use packets)

Still don't really know how it works though. You can try setting the player passenger of an item first.

 

The player would pick up the item (unless you cancel that) and wouldn't be able to move.

Forgo to tag you, bergerkiller

 

Does this show for everyone on the server (like can everyone see the palyer with the potions) or just the player?

Ughh, so I added this into my class, and I"m getting soo many errors, It doens't know what the Packet40 is, or what datawatcher is... I have 0 idea on how to fix it. Am I missing an import? Implemtation, extension?

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

CraftBukkit, I think....