如何使 b2body 多边形绕其质心旋转？
这应该不难，但我无法让它发挥作用。
基本上，用户通过在屏幕上绘制线条来创建 b2body 多边形。我希望 b2body 旋转（或绕其质心旋转）。我可以对我制作的所有其他形状执行此操作，因为它们的位置已经设置为中心。但是当我制作 b2PolygonShape 时，位置设置为 0,0。因为用户正在制作形状，所以我无法确定它的质心在哪里。即使我确实知道，我似乎也无法围绕它旋转。我尝试了ApplyAngularVelocity，但对象绕原点（0,0）旋转。我尝试了ApplyTorque，但该对象完全没有执行任何操作。它就坐在那里。请帮忙。
This shouldn't be hard but I can't get it to work.
Basically, the user creates a b2body polygon by making lines on the screen. I want that b2body to spin (or rotate around it's mass center). I can do this with all the other shapes I make because their position is already set to their center. But when I make a b2PolygonShape the position is set to 0,0. Because the user is making the shape I can't be sure where it's mass center is. And even if I did know I can't seem to rotate around it. I tried ApplyAngularVelocity but the object spun around the origin (0,0). I tried ApplyTorque and the object did absolutely nothing. It just sat there. Please help.
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ApplyTorque 或 ApplyAngularImpulse 应该可以做到。检查主体是否具有非零转动惯量且未设置为固定旋转。
可以使用 GetWorldCenter() 找到质心。
ApplyTorque or ApplyAngularImpulse should do it. Check that the body has a non-zero rotational inertia and is not set to be fixedRotation.
The center of mass can be found with GetWorldCenter().