PhysicsSystem.java

package com.siondream.core.entity.systems;

import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.physics.box2d.Transform;
import com.siondream.core.entity.components.OverridePhysicsComponent;
import com.siondream.core.entity.components.PhysicsComponent;
import com.siondream.core.entity.components.TransformComponent;

import ashley.core.Entity;
import ashley.core.Family;
import ashley.systems.IteratingSystem;

public class PhysicsSystem extends IteratingSystem {

	float alpha;
	
	public PhysicsSystem() {
		super(Family.getFamilyFor(PhysicsComponent.class,
								  TransformComponent.class));
		
		alpha = 1.0f;
	}

	@Override
	public void update(float deltaTime) {
		super.update(deltaTime);
	}
	
	@Override
	public void processEntity(Entity entity, float deltaTime) {
		PhysicsComponent physics = entity.getComponent(PhysicsComponent.class);
		TransformComponent transform = entity.getComponent(TransformComponent.class);
		OverridePhysicsComponent override = entity.getComponent(OverridePhysicsComponent.class);
		
		Transform bodyTransform = physics.body.getTransform();
		
		if (override != null && override.enable) {
			Vector2 bodyPosition = bodyTransform.getPosition();
			bodyPosition.set(transform.position.x, transform.position.y);
			physics.body.setTransform(bodyPosition, transform.angle);
			
			if (override.autoDisable) {
				override.enable = false;
			}
		}
		else {
			Vector2 bodyPosition = bodyTransform.getPosition();
			transform.position.x = bodyPosition.x * alpha + transform.position.x * (1.0f - alpha);
			transform.position.y = bodyPosition.y * alpha + transform.position.y * (1.0f - alpha);
			transform.angle = bodyTransform.getRotation() * alpha + transform.angle * (1.0f - alpha);
		}
	}

	public void interpolate(float deltaTime, float alpha) {
		this.alpha = alpha;
		super.update(deltaTime);
		alpha = 1.0f;
	}
}