当物体被磁化时 box2d 抖动
所以我有一些物体（我可以在运行时创建越来越多的物体），我需要它们被磁化到屏幕中心。让它在世界空间中为 (480/2 / WORLD_SCALE, 320/2 / WORLD_SCALE)。我是 box2d 的新手，所以也许有一种简单的方法可以实现这一点，但我正在尝试执行以下操作：
- 我减去每个身体的位置和屏幕中心位置 - 以获得我需要将身体移动到的方向。
- 标准化方向向量（我在第 1 页中找到的）
- 将此标准化向量乘以我的重力功率值
- 将向量（我在第 3 页中找到的）添加到当前身体的速度
所以之后我得到了什么我想要 - 物体确实会磁化到屏幕中心，我还添加了一些摩擦力和阻尼，以便物体可以停止。但是，正如我假设的那样，由于我的重力矢量是恒定长度 - 我无法强迫物体完全停止移动。它总是试图将自己移动到屏幕中心，并且它们可能的最小速度 - 是该重力矢量的长度。
如果我只有一个身体，当身体距离屏幕中心比重力大小更近时，我不会执行步骤 2,3。但我无法将物体的位置绑定到磁场中心，因为两个物体永远不会占据精确的屏幕中间位置，因为它们会相互碰撞。所以我不能使我的重力矢量可变，并且玩弄任何摩擦力都不起作用，也许一些步骤黑客可以帮助，但我认为我需要的是实现某种弹跳反作用力或类似的东西。
我是 box2d 的新手，对物理不太了解。
同样重要的是我使用 SetLinearVelocity 方法设置物体速度。
也许我只是错过了一些东西，也许有一些 box2d 原生的方法来实现这一点。任何帮助表示赞赏。
So i have some bodies(which i can create more and more at runtime), and i need them to be magnetized to the screen center. Let it be a (480/2 / WORLD_SCALE, 320/2 / WORLD_SCALE) in the world space. I am new to box2d so maybe there is an easy way to achieve this, but i am trying to do it as following:
- I subtract each bodie's position and screen center position - to get a direction to where i need to move my body to.
- Normalize the direction vector(which i've found in p.1)
- Multiply this normalized vector to my gravity power value
- Add the vector(that i've got in the p. 3) to the current bodie's speed
So after that i get what i want - bodies do magnetize to the screen center, i also add some frictions, and dampings so that bodies could ever stop. But, as i assume, because of my gravity vector to be constant length - i cannot force the bodies to stop moving completely. It always tries to move itself to the screen center and the smallest possible speed for them - is the length of this gravity vector.
If i only had one body, i would not perform steps 2,3 when the body is closer to the screen center then the gravity size is. But i can not bind bodie's position to the magnetic field center because the two bodies will never take the exact middle screen place since they will collide with each other. So i cannot make my gravity vector variable, and playing around with any frictions do not do the trick, maybe some step hack could help, but i think what i need is to implement some sort of bouncing counter force or something of that kind.
I am new to box2d, and not very good with physics.
What may also be important is that i set the bodies speed with the SetLinearVelocity method.
Maybe i am just missing something, maybe there is some native for box2d way to achieve this. Any help appreciated.
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（1）
确实通过改变世界规模解决了这个问题。 “当碰撞速度较小时，Box2D 也会使用非弹性碰撞。这样做是为了防止抖动。” http://www.box2d.org/manual.html
读完后，我发现我应该使加速度矢量足够小，以便 box2d 使用这种非弹性碰撞并防止其以“本机”方式抖动。因此，将 WORLD_SCALE 增加 4 倍可以使物体与屏幕中心之间的距离足够大。尝试使用新的引力和摩擦力数字就成功了。
问候，伊戈尔
Did solve this issue by changing world scale. "Box2D also uses inelastic collisions when the collision velocity is small. This is done to prevent jitter." http://www.box2d.org/manual.html
After reading that i figured out that i should make my acceleration vector small enough so that box2d used this inelastic collisions and prevent its jittering in "native" way. So increasing WORLD_SCALE by 4 times made the distances between bodies and the screen center big enough. Playing around with new numbers for gravitation and friction powers made the trick.
Regards, Igor