UpgradeMagnet.java

package chbachman.armour.upgrade.upgradeList;

import java.util.List;

import net.minecraft.entity.item.EntityItem;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.item.ItemStack;
import net.minecraft.util.AxisAlignedBB;
import net.minecraft.world.World;
import chbachman.api.configurability.Configurable;
import chbachman.api.configurability.ConfigurableField;
import chbachman.api.upgrade.Upgrade;
import chbachman.api.util.ArmourSlot;
import chbachman.armour.util.ConfigHelper;

public class UpgradeMagnet extends Upgrade {

    public UpgradeMagnet() {
        super("magnet");
    }

    private int cost;

    @Configurable
    public ConfigurableField f = new ConfigurableField(this, "reach");

    @Override
    public void registerConfigOptions() {
        cost = ConfigHelper.get(ConfigHelper.SPEED, this, "energy cost to drag items in, per item", 100);
    }

    @Override
    public int onTick(World world, EntityPlayer player, ItemStack stack, ArmourSlot slot) {
        float distanceToPull = 5 * f.get(stack).getPercentage();

        AxisAlignedBB box = player.boundingBox.expand(distanceToPull, distanceToPull, distanceToPull);

        @SuppressWarnings("unchecked")
        List<EntityItem> list = world.getEntitiesWithinAABB(EntityItem.class, box);

        int energy = 0;

        for (EntityItem e : list) {
            if (e.age >= 10) {
                double x = player.posX - e.posX;
                double y = player.posY - e.posY;
                double z = player.posZ - e.posZ;

                double length = Math.sqrt(x * x + y * y + z * z) * 2;

                x = x / length + player.motionX / 2;
                y = y / length + player.motionY / 2;
                z = z / length + player.motionZ / 2;

                e.motionX = +x;
                e.motionY = +y;
                e.motionZ = +z;
                e.isAirBorne = true;

                if (e.isCollidedHorizontally) {
                    e.motionY += 1;
                }

                energy += cost;
            }
        }

        return energy;
    }

}