Farseer - Particles doesn´t move/bounce accord to borders

问题

I made my borders with this:

class Maze
    {
        private Body _agentBody;
        private Sprite _box;
        private GameplayScreen _screen;
        private float _offset;

        public Maze(World world, GameplayScreen screen, Vector2 position)
        {
            _agentBody = BodyFactory.CreateBody(world, position);
            _agentBody.BodyType = BodyType.Dynamic;
            _agentBody.IsStatic = true;
            _agentBody.Restitution = 0.2f;
            _agentBody.Friction = 0.2f;

            _offset = ConvertUnits.ToDisplayUnits(1f);
        // spodek
            _agentBody.CreateFixture(new PolygonShape(PolygonTools.CreateRectangle(1f, 0.05f, new Vector2(0f, 1f), 0), 1f));
            // spodek
            _agentBody.CreateFixture(new PolygonShape(PolygonTools.CreateRectangle(1f, 0.05f, new Vector2(0f, -1f), 0), 1f));
            // pravy bok
            _agentBody.CreateFixture(new PolygonShape(PolygonTools.CreateRectangle(0.05f, 1f, new Vector2(1f, 0f), 0), 1f));
            // levy bok
            _agentBody.CreateFixture(new PolygonShape(PolygonTools.CreateRectangle(0.05f, 1f, new Vector2(-1f, 0f), 0), 1f));   
            _screen = screen;

            //GFX
            AssetCreator creator = _screen.ScreenManager.Assets;
            _box = new Sprite(creator.TextureFromVertices(PolygonTools.CreateRectangle(1f, 0.05f),
                                                           MaterialType.Blank, Color.White, 1f));
        }

        public Body Body
        {
            get { return _agentBody; }
        }

        public void Draw()
        {
            SpriteBatch batch = _screen.ScreenManager.SpriteBatch;
            batch.Draw(_box.Texture, ConvertUnits.ToDisplayUnits(_agentBody.Position), null,
                        Color.White, _agentBody.Rotation, _box.Origin + new Vector2(0f, _offset), 1f, SpriteEffects.None, 0f);
            batch.Draw(_box.Texture, ConvertUnits.ToDisplayUnits(_agentBody.Position), null,
                        Color.White, _agentBody.Rotation, _box.Origin + new Vector2(0f, -_offset), 1f, SpriteEffects.None, 0f);

            batch.Draw(_box.Texture, ConvertUnits.ToDisplayUnits(_agentBody.Position), null,
                        Color.White, _agentBody.Rotation + MathHelper.Pi / 2f, _box.Origin + new Vector2(0f, _offset), 1f, SpriteEffects.None, 0f);
            batch.Draw(_box.Texture, ConvertUnits.ToDisplayUnits(_agentBody.Position), null,
                        Color.White, _agentBody.Rotation + MathHelper.Pi / 2f, _box.Origin + new Vector2(0f, -_offset), 1f, SpriteEffects.None, 0f);
        }

    }

And these are my little particles:

for (int i = 0; i < 8; i++)
            {
                _sands[i] = BodyFactory.CreateRectangle(_world, 0.05f, 0.05f, 1f);
                _sands[i].IsStatic = false;
                _sands[i].Restitution = 0.1f;
                _sands[i].Friction = 0.1f;
                _sands[i].Position = new Vector2(1.8f + i * 0.2f, 2.2f);
            }

            _sand = new Sprite(ScreenManager.Assets.TextureFromShape(_sands[0].FixtureList[0].Shape,
                                                                        MaterialType.Dots,
                                                                        Color.SandyBrown, 0.8f));

I draw it this way:

foreach (Body sand in _sands)
            {
                spriteBatch.Draw(_sand.Texture, ConvertUnits.ToDisplayUnits(sand.Position), null, Color.SandyBrown, sand.Rotation, _sand.Origin, 1f, SpriteEffects.None, 0f);
            }
_maze.Draw();

But I can't figure out why if I rotate with borders then why partlicles are still in place. I tried change restitution of particles and when there is 1f they are restitute (bouncing) allright and I can rotate with borders and they restitute from new position of borders but when I have settings like above particles fall down, the ones which are inside of borders they stopped at bottom border and others fall down entirely. So after start I have first image and after I rotate with borders I get seccond image. What I am doing wrong? Why when I change restitution they are bouncing a with 0.2 they are not?

Edit: New lines in maze constructor:

agentBody = BodyFactory.CreateBody(world, position);
            _agentBody.BodyType = BodyType.Dynamic;
            _agentBody.IgnoreGravity = true;
            _agentBody.Restitution = 0.1f;
            _agentBody.Friction = 1f;

            _offset = ConvertUnits.ToDisplayUnits(1.5f);

            FixtureFactory.AttachRectangle(3f, 0.1f, 1f, new Vector2(0, 1.55f), _agentBody);
            FixtureFactory.AttachRectangle(3f, 0.1f, 1f, new Vector2(0f, -1.55f), _agentBody);
            FixtureFactory.AttachRectangle(width, 3f, 1f, new Vector2(-1.55f, 0f), _agentBody);
            FixtureFactory.AttachRectangle(width, 3f, 1f, new Vector2(1.55f, 0f), _agentBody);

This is how it looks with debug view:

Rotating with body:

public override void HandleInput(GameTime gameTime, InputState input)
{
    if (input == null)
        throw new ArgumentNullException("input");

    // Read in our gestures
    foreach (GestureSample gesture in input.Gestures)
    {
        if (gesture.GestureType == GestureType.HorizontalDrag)
        {
            if (gesture.Delta.X < 0)
            {
                _maze.Body.Rotation += 0.02f;
            }
            else if (gesture.Delta.X > 0)
            {
                _maze.Body.Rotation -= 0.02f;
            }
        }
    }

回答1:

The little particle bodies are probably sleeping once they stop moving. The frame around them is a static body so the engine does not expect it to ever move, but you are moving it. In this situation the little particle bodies will not wake up.

You will need to set the little particle bodies so that they cannot sleep, or make the frame around them a dynamic or kinematic body. As a general rule, if a body is gonna move, don't make it a static body.

来源：https://stackoverflow.com/questions/12833724/farseer-particles-doesn%c2%b4t-move-bounce-accord-to-borders