[Tutorial] Riding two players in one entity.

This tutorial is a way to enable two player riding on an entity.

The link below shows you what you're done with.

https://imgur.com/Z7Xo9ou

STEP1

1. Create a custom entity.
2. Check the ride function.
3. Save.

STEP2

1. Open the Code Editor.
2. Add an import.

import java.util.ArrayList;
import java.util.List;

3. Modify the code.

The original code 1

*Change the 'test' part of the code to the 'name of the Workspace AND Entity name.'

public class TestEntity extends Monster {
public TestEntity(PlayMessages.SpawnEntity packet, Level world) {
 this(TestModEntities.TEST.get(), world);
 }

Changed code 1

public class TestEntity extends Monster {
private List<Entity> customPassengers = new ArrayList<>(); // Add Code
public TestEntity(PlayMessages.SpawnEntity packet, Level world) {
this(TestModEntities.TEST.get(), world);
}

The original code 2

@Override
 public InteractionResult mobInteract(Player sourceentity, InteractionHand hand) {
 ItemStack itemstack = sourceentity.getItemInHand(hand);
 InteractionResult retval = InteractionResult.sidedSuccess(this.level().isClientSide());
 super.mobInteract(sourceentity, hand);
 sourceentity.startRiding(this);
 return retval;
  }

Changed code 2

@Override
   public InteractionResult mobInteract(Player sourceentity, InteractionHand hand) {
       ItemStack itemstack = sourceentity.getItemInHand(hand);
       InteractionResult retval = super.mobInteract(sourceentity, hand);
       if (!this.customPassengers.contains(sourceentity) && this.customPassengers.size() < 2) { // Add Riding 2 players.
           sourceentity.startRiding(this, true); // Add Code
           customPassengers.add(sourceentity); // Add Code
       }
       return retval;
   }

The original code 3

@Override
    public void travel(Vec3 dir) {
        Entity entity = this.getPassengers().isEmpty() ? null : (Entity) this.getPassengers().get(0);
        if (this.isVehicle()) {
            this.setYRot(entity.getYRot());
            this.yRotO = this.getYRot();
            this.setXRot(entity.getXRot() * 0.5F);
            this.setRot(this.getYRot(), this.getXRot());
            this.yBodyRot = entity.getYRot();
            this.yHeadRot = entity.getYRot();
            if (entity instanceof LivingEntity passenger) {
                this.setSpeed((float) this.getAttributeValue(Attributes.MOVEMENT_SPEED));
                float forward = passenger.zza;
                float strafe = passenger.xxa;
                super.travel(new Vec3(strafe, 0, forward));
            }
            double d1 = this.getX() - this.xo;
            double d0 = this.getZ() - this.zo;
            float f1 = (float) Math.sqrt(d1 * d1 + d0 * d0) * 4;
            if (f1 > 1.0F)
                f1 = 1.0F;
            this.walkAnimation.setSpeed(this.walkAnimation.speed() + (f1 - this.walkAnimation.speed()) * 0.4F);
            this.walkAnimation.position(this.walkAnimation.position() + this.walkAnimation.speed());
            this.calculateEntityAnimation(true);
            return;
        }
        super.travel(dir);
    }

Changed code 3

@Override
   public void travel(Vec3 dir) {
       if (this.isVehicle() && !this.customPassengers.isEmpty()) { // Add Code
           Entity entity = this.customPassengers.get(0); // Add Code
           this.setYRot(entity.getYRot());
           this.yRotO = this.getYRot();
           this.setXRot(entity.getXRot() * 0.5F);
           this.setRot(this.getYRot(), this.getXRot());
           this.yBodyRot = entity.getYRot();
           this.yHeadRot = entity.getYRot();
           if (entity instanceof LivingEntity passenger) {
               this.setSpeed((float) this.getAttributeValue(Attributes.MOVEMENT_SPEED));
               float forward = passenger.zza;
               float strafe = passenger.xxa;
               super.travel(new Vec3(strafe, 0, forward));
           }
           double d1 = this.getX() - this.xo;
           double d0 = this.getZ() - this.zo;
           float f1 = (float) Math.sqrt(d1 * d1 + d0 * d0) * 4;
           if (f1 > 1.0F)
               f1 = 1.0F;
           this.walkAnimation.setSpeed(this.walkAnimation.speed() + (f1 - this.walkAnimation.speed()) * 0.4F);
           this.walkAnimation.position(this.walkAnimation.position() + this.walkAnimation.speed());
           this.calculateEntityAnimation(true);
           this.setMaxUpStep(1.0f); // Makes you climb the hill when you have a rider in the entity.
       return;
       }
       super.travel(dir);
   }

Lastly, please add the code.

    public static AttributeSupplier.Builder createAttributes() {
       AttributeSupplier.Builder builder = Mob.createMobAttributes();
       builder = builder.add(Attributes.MOVEMENT_SPEED, 0.3);
       builder = builder.add(Attributes.MAX_HEALTH, 10);
       builder = builder.add(Attributes.ARMOR, 0);
       builder = builder.add(Attributes.ATTACK_DAMAGE, 3);
       builder = builder.add(Attributes.FOLLOW_RANGE, 16);
       return builder;
   }

//Please add the following code below this code.

@Override
protected void positionRider(Entity passenger, MoveFunction moveFunction) {
        if (this.hasPassenger(passenger)) {
            int passengerIndex = this.getPassengers().indexOf(passenger);
            double offsetX = this.getX();
            double offsetY = this.getY() + 1.0D + passenger.getMyRidingOffset(); // Change ride Y height
            double offsetZ = this.getZ();

       if (passengerIndex == 0) {
           // Location of the first passenger
           offsetX = this.getX();
           offsetZ = this.getZ();
       } else if (passengerIndex == 1) {
           // Second passenger's position
           offsetX = this.getX() - Math.sin(Math.toRadians(this.getYRot())) * -1.0D;
           offsetZ = this.getZ() + Math.cos(Math.toRadians(this.getYRot())) * -1.0D;
       }

       passenger.setPos(offsetX, offsetY, offsetZ);
   }
}
}

Save and test the code.

It was completed by exchanging many questions and answers with Copilot(AI) to find this method.