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/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.replica.replicaisland;
public class OrbitalMagnetComponent extends GameComponent {
private final static float DEFAULT_STRENGTH = 15.0f;
private float mStrength;
private Vector2 mCenter;
private Vector2 mDelta;
private Vector2 mRim;
private Vector2 mVelocity;
private float mMagnetRadius;
private float mAreaRadius;
public OrbitalMagnetComponent() {
super();
mCenter = new Vector2();
mDelta = new Vector2();
mRim = new Vector2();
mVelocity = new Vector2();
reset();
setPhase(ComponentPhases.COLLISION_DETECTION.ordinal());
}
@Override
public void reset() {
mCenter.zero();
mDelta.zero();
mRim.zero();
mVelocity.zero();
mStrength = DEFAULT_STRENGTH;
mAreaRadius = 0.0f;
mMagnetRadius = 0.0f;
}
@Override
public void update(float timeDelta, BaseObject parent) {
GameObjectManager manager = sSystemRegistry.gameObjectManager;
if (manager != null) {
GameObject player = manager.getPlayer();
if (player != null) {
GameObject parentObject = (GameObject)parent;
applyMagnetism(player,
parentObject.getCenteredPositionX(),
parentObject.getCenteredPositionY(),
timeDelta);
}
}
}
private void applyMagnetism(GameObject target, float centerX, float centerY, float timeDelta) {
mCenter.set(centerX, centerY);
final float targetX = target.getCenteredPositionX();
final float targetY = target.getCenteredPositionY();
mDelta.set(targetX, targetY);
mDelta.subtract(mCenter);
final float distanceFromCenter2 = mDelta.length2();
final float area2 = mAreaRadius * mAreaRadius;
if (distanceFromCenter2 < area2) {
mRim.set(mDelta);
mRim.normalize();
mRim.multiply(mMagnetRadius);
mRim.add(mCenter);
// rim is now the closest point on the magnet circle
// remove gravity
final Vector2 targetVelocity = target.getVelocity();
GravityComponent gravity = target.findByClass(GravityComponent.class);
final Vector2 gravityVector = gravity.getGravity();
mVelocity.set(gravityVector);
mVelocity.multiply(timeDelta);
targetVelocity.subtract(mVelocity);
mDelta.add(targetVelocity);
mDelta.normalize();
mDelta.multiply(mMagnetRadius);
mDelta.add(mCenter);
// mDelta is now the next point on the magnet circle in the direction of
// movement.
mDelta.subtract(mRim);
mDelta.normalize();
// Now mDelta is the tangent to the magnet circle, pointing in the direction
// of movement.
mVelocity.set(mDelta);
mVelocity.normalize();
// mVelocity is now the direction to push the player
mVelocity.multiply(mStrength);
float weight = 1.0f;
if (distanceFromCenter2 > mMagnetRadius * mMagnetRadius) {
float distance = (float)Math.sqrt(distanceFromCenter2);
weight = (distance - mMagnetRadius) / (mAreaRadius - mMagnetRadius);
weight = 1.0f - weight;
mVelocity.multiply(weight);
}
final float speed = targetVelocity.length();
targetVelocity.add(mVelocity);
if (targetVelocity.length2() > (speed * speed)) {
targetVelocity.normalize();
targetVelocity.multiply(speed);
}
}
}
public void setup(float areaRadius, float orbitRadius) {
mAreaRadius = areaRadius;
mMagnetRadius = orbitRadius;
}
}
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