com.artemis.EntityTransmuter Maven / Gradle / Ivy

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package com.artemis;

import com.artemis.utils.Bag;

import java.util.BitSet;

/**
 * Fastest way of changing entity component compositions. Primarily useful when
 * bootstrapping entities over several different managers/systems or when
 * dealing with many entities at the same time (light particle systems etc).
 * 
 * Given a set of component additions/removals: for each encountered
 * compositionId, cache the calculated new compositionId. This extends
 * the performance benefits introduced with
 * {@link com.artemis.Archetype Archetypes} in 0.7.0 to carry over to existing entities.
 * 
 * @see com.artemis.EntityTransmuterFactory
 */
public final class EntityTransmuter {
	private final World world;
	private final BitSet additions;
	private final BitSet removals;
	private final Bag operations;

	private final BitSet bs;

	EntityTransmuter(World world, BitSet additions, BitSet removals) {
		this.world = world;
		this.additions = additions;
		this.removals = removals;
		operations = new Bag();

		bs = new BitSet();
	}

	public void transmute(Entity e) {
		// if entity was just created, we can resolve,
		// but otherwise we need to make sure the instance
		// isn't a flyweight instance escaping system processing,
		// if so we need to resolve it to the actual entity.
		e = world.getEntity(e.id);

		TransmuteOperation operation = getOperation(e);

		operation.perform(e, world.getComponentManager());
		world.getEntityManager().setIdentity(e, operation);

		if (e.isActive())
			world.changed.set(e.id);
		else
			world.added.set(e.id);
	}

	private TransmuteOperation getOperation(Entity e) {
		if (world.editPool.isEdited(e)) {
			world.editPool.processAndRemove(e);
		}

		int compositionId = e.getCompositionId();
		TransmuteOperation operation = operations.safeGet(compositionId);
		if (operation == null) {
			operation = createOperation(e);
			operations.set(compositionId, operation);
		}
		return operation;
	}

	private TransmuteOperation createOperation(Entity e) {
		BitSet origin = e.getComponentBits();
		bs.clear();
		bs.or(origin);
		bs.or(additions);
		bs.andNot(removals);
		int compositionId = world.getEntityManager().compositionIdentity(bs);
		return new TransmuteOperation(compositionId, getAdditions(origin), getRemovals(origin));
	}

	private Bag getAdditions(BitSet origin) {
		ComponentTypeFactory tf = world.getComponentManager().typeFactory;
		Bag types = new Bag();
		for (int i = additions.nextSetBit(0); i >= 0; i = additions.nextSetBit(i + 1)) {
			if (!origin.get(i))
				types.add(tf.getTypeFor(i));
		}

		return types;
	}

	private Bag getRemovals(BitSet origin) {
		ComponentTypeFactory tf = world.getComponentManager().typeFactory;
		Bag types = new Bag();
		for (int i = removals.nextSetBit(0); i >= 0; i = removals.nextSetBit(i + 1)) {
			if (origin.get(i))
				types.add(tf.getTypeFor(i));
		}

		return types;
	}

	@Override
	public String toString() {
		return "EntityTransmuter(add=" + additions + " remove=" + removals + ")";
	}

	static class TransmuteOperation {
		private Bag additions;
		private Bag removals;
		public final int compositionId;

		public TransmuteOperation(int compositionId, Bag additions, Bag removals) {
			this.compositionId = compositionId;
			this.additions = additions;
			this.removals = removals;
		}

		public void perform(Entity e, ComponentManager cm) {
			for (int i = 0, s = additions.size(); s > i; i++)
				cm.create(e, additions.get(i));

			for (int i = 0, s = removals.size(); s > i; i++)
				cm.removeComponent(e, removals.get(i));
		}

		@Override
		public String toString() {
			StringBuilder sb = new StringBuilder();
			sb.append("TransmuteOperation(");

			if (additions.size() > 0) {
				sb.append("add={");
				String delim = "";
				for (ComponentType ct : additions) {
					sb.append(delim).append(ct.getType().getSimpleName());
					delim = ", ";
				}
				sb.append("}");
			}

			if (removals.size() > 0) {
				if (additions.size() > 0)
					sb.append(" ");

				sb.append("remove={");
				String delim = "";
				for (ComponentType ct : removals) {
					sb.append(delim).append(ct.getType().getSimpleName());
					delim = ", ";
				}
				sb.append("}");
			}
			sb.append(")");

			return sb.toString();
		}
	}
}