Item interact with block

Hi, i want to create Melon Launcher but i don't know how to get the item who was interact with block.

 

describe the melon launcher

 

I click with melon block and launch the melon and when melon hit the block melon despawn and create a lot of diamonds.

 

You'll need to create and register a new projectile for this, let's name it "MelonBullet".

PHP:

<?php
namespace space\name;

use pocketmine\entity\Projectile;

class MelonBullet extends Projectile {

    const NETWORK_ID = 64;//item id of DroppedItem in MCPE. Refer: http://minecraft.gamepedia.com/Pocket_Edition_data_values#Entity_IDs
}


As you've given only one condition, and that is when it collides with the ground, we'll need to make MelonBullet::canCollideWith(Entity) always return false. We don't want the bullet die after colliding with any entity.

PHP:

//class MelonBullet
//If you are reading this in the future, @dktapps has probably
//type-hinted this function, so please avoid quoting this message
//with a "Declaration of Projectile::canCollideWith()..." error.
public function canCollideWith(Entity $entity){
    return false;
}


Now we need to create A LOT of diamonds when the bullet collides with the ground. For this, we'll use Level::dropItem() function and override Projectile:: onUpdate().

PHP:

//class MelonBullet

const NUMBER_OF_DIAMONDS = [5, 10];//we will choose a random number between 5 and 10

//This method might get type-hinted too, in the future.
public function onUpdate($currentTick){
    $result = parent::onUpdate($currentTick);
    if($this->hadCollision){//$hadCollision = projectile has hit the ground. I think $onGround does the same thing, not sure.
        $level = $this->getLevel();
        if($level !== null){
            $numberOfDiamonds = mt_rand(...MelonBullet::NUMBER_OF_DIAMONDS);
            //TIP: Try calling as less methods as possible in loops. Loops aren't meant to be abused.
            $diamond = Item::get(Item::DIAMOND);
            for($i = 0; $i < $numberOfDiamonds; $i++){
                $level->dropItem($this, $diamond);
            }
        }
        //now we need to despawn the bullet as we do not need it anymore.
        $this->close();
    }
    return $result;
}


Now the graphics part. This function is responsible for how the projectile will look like. MelonBullet is actually an item entity.

PHP:

//class MelonBullet
public function spawnTo(Player $player){
    //YES, this if statement is important. parent::spawnTo() does it and calling it instead is okay...not!
    //We want to avoid double or triple spawning. Aside from that, the close() function is useless without
    //this if statement as there is gonna be no way to detect whom the projectile has been spawned to,
    //while despawning it.
    if(!isset($this->hasSpawned[$player->getLoaderId()]) and isset($player->usedChunks[Level::chunkHash($this->chunk->getX(), $this->chunk->getZ())])){
        $pk = new AddItemEntityPacket();
        $pk->entityRuntimeId = $player->getId();
        $pk->item = Item::get(Item::MELON_SLICE);//Hey, glistering melons would look better :D
        $pk->x = $this->x;
        $pk->y = $this->y;
        $pk->z = $this->z;
        $pk->metadata = $this->dataProperties;
        $this->hasSpawned[$player->getLoaderId()] = $player;
    }
}


Now that you've done it, you'll need to register the class on startup. Make sure this is executed BEFORE we throw the entity. Try calling this in Plugin:: onEnable()

PHP:

    Entity::registerEntity(MelonBullet::class);


Now listen to PlayerInteractEvent and create the entity and set it's motion to what ever you prefer.

PHP:

/** @var PlayerInteractEvent $event */
if($event->getItem()->getId() === Item::MELON_BLOCK){
    $pos = $event->getPlayer()->getLocation();//location where the bullet will be spawned at.
    $bullet = Entity::createEntity("MelonBullet", $pos->getLevel(), new CompoundTag("", [
        new ListTag("Pos", [
            new DoubleTag("", $pos->x),
            new DoubleTag("", $pos->y + $event->getPlayer()->getEyeHeight()),
            new DoubleTag("", $pos->z),
        ]),
        new ListTag("Motion", [
            new DoubleTag("", -sin($pos->yaw / 180 * M_PI) * cos($pos->pitch / 180 * M_PI)),
            new DoubleTag("", -sin($pos->pitch / 180 * M_PI)),
            new DoubleTag("", cos($pos->yaw / 180 * M_PI) * cos($pos->pitch / 180 * M_PI)),
        ]),
        new ListTag("Rotation", [
            new FloatTag("", $pos->yaw),
            new FloatTag("", $pos->pitch),
        ]),
    ]));
    $force = 1.4;//this is your preference.
    $bullet->setMotion($bullet->getMotion()->multiply($force));
    $bullet->spawnToAll();//spawns the bullet to everyone.
}


 

Nice tutorial : D