Есть ряд проблем с вашим кодом .... но этот ответ, вероятно, слишком поздно, чтобы быть полезным в любом случае.
Во-первых, world.createBody () устарела.Теперь вам нужно явно вызвать world.createDynamicBody () в последней версии Jar Android Box2D, которая у меня есть.
В любом случае ... моя версия выглядит примерно так ... не идеально, но по крайней мере динамично.
package com.box2D;
import java.util.ArrayList;
import org.jbox2d.collision.AABB;
import org.jbox2d.collision.CircleDef;
import org.jbox2d.collision.PolygonDef;
import org.jbox2d.common.Vec2;
import org.jbox2d.dynamics.Body;
import org.jbox2d.dynamics.BodyDef;
import org.jbox2d.dynamics.World;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.Log;
public class PhysicsWorld
{
public float timeStep = 1;
public int iterations = 1;
private ArrayList<Body> bodies;
private int count = 0;
private AABB worldAABB;
private World world;
private BodyDef groundBodyDef;
private PolygonDef boxShapeDef;
//a paint
private Paint paint;
public void create()
{
//create the paint
paint = new Paint();
paint.setColor(0xFFFFFF);
// Step 1: Create Physics World Boundaries
worldAABB = new AABB();
worldAABB.lowerBound.set(new Vec2((float) -100.0, (float) -100.0));
worldAABB.upperBound.set(new Vec2((float) 100.0, (float) 300.0));
// Step 2: Create Physics World with Gravity
Vec2 gravity = new Vec2((float) 0.0, (float)10.0);
boolean doSleep = true;
world = new World(worldAABB, gravity, doSleep);
bodies = new ArrayList<Body>();
// Step 3: Create Ground Box
groundBodyDef = new BodyDef();
groundBodyDef.position.set(new Vec2((float) 0.0, (float) 300.0));
Body groundBody = world.createDynamicBody(groundBodyDef);
boxShapeDef = new PolygonDef();
boxShapeDef.setAsBox((float) 50.0, (float) 10.0);
groundBody.createShape(boxShapeDef);
}
public void addBall()
{
// Create Dynamic Body
BodyDef bodyDef = new BodyDef();
bodyDef.position.set((float)16.0+(count * 10), (float)24.0);
Body newBody = world.createDynamicBody(bodyDef);
// Create Shape with Properties
CircleDef circle = new CircleDef();
circle.radius = (float)5;
circle.density = (float)1.0;
// Assign shape to Body
newBody.createShape(circle);
newBody.setMassFromShapes();
newBody.m_userData = "Circle";
bodies.add(newBody);
// Increase Counter
count += 1;
}
public void addBox()
{
// Create Dynamic Body
BodyDef bodyDef = new BodyDef();
bodyDef.position.set((float)36.0+(count * 10), (float)24.0);
Body newBody = world.createDynamicBody(bodyDef);
// Create Shape with Properties
boxShapeDef = new PolygonDef();
boxShapeDef.setAsBox((float) 50.0, (float) 10.0);
// Assign shape to Body
newBody.createShape(boxShapeDef);
newBody.setMassFromShapes();
newBody.m_userData = "Box";
bodies.add(newBody);
// Increase Counter
count += 1;
}
/*
*
*
* Physics Update
*/
private Vec2 position;
private float angle;
public void Update(Canvas canvas)
{
// Update Physics World
world.step(timeStep/5, 1);
// Print info of latest body
for (Body i : bodies)
{
position = i.getPosition();
angle = i.getAngle();
if(i.m_userData == "Circle")
canvas.drawCircle(position.x, position.y, 5,paint );
if(i.m_userData == "Box")
canvas.drawRect((float)(position.x -5), (float)(position.y - 5), (float)(position.x + 5), (float)(position.y + 5), paint );
Log.v("Physics Test", "Pos: (" + position.x + ", " + position.y + "), Angle: " + angle);
}
}
}