RealityKit – transform.rotate() 使对象的比例更大 [英] RealityKit – transform.rotate() makes object bigger in scale

问题描述

我正在尝试旋转 RealityKit 入门代码中给出的钢盒，我使用此代码

I'm trying to rotate the steel box given in the starter code for RealityKit, and I use this code

steelBox.transform.rotation += simd_quatf(angle: radians,
                                           axis: SIMD3<Float>(0, 1, 0)) 

尝试旋转对象.

然而，当物体旋转时，它也会在一维上变大.

When the object rotates, however, it grows bigger in one dimension as well.

这是为什么?

推荐答案

如果您正在累积四元数旋转，您可能希望使用:

If it's a quaternion rotation you are accumulating, you probably want to be using either:

steelBox.transform.rotation = 
   simd_mul(steelBox.transform.rotation, 
           simd_quatf(angle: radians,
                      axis: SIMD3<Float>(0, 1, 0)) )

或

steelBox.transform.rotation = 
   simd_mul(simd_quatf(angle: radians,
                       axis: SIMD3<Float>(0, 1, 0)),
            steelBox.transform.rotation )

取决于您是要在初始方向之前还是之后添加"旋转(我不确定是哪个，因为这取决于 simd_mul 是 parent * child 还是 child * parent - 苹果文档没有说明哪个?).

depending on whether you want to 'add' the rotation in pre or post the initial orientation (I'm not sure which, because it depends on whether simd_mul does parent * child, or child * parent - the apple docs don't state which?).

四元数遵循与变换矩阵相同的规则.因此，如果您在谈论添加"(累积) 轮换，则实际上是指乘以".在四元数上使用加法运算符将传递缩放操作.

quaternions follow the same rules as with transformation matrices. So if you are talking about 'adding' (accumulating) a rotation, you actually mean 'multiply'. Using the addition operator on a quaternion will impart a scaling operation.

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