SceneKit 相机，如何补偿欧拉规则(方向)变化 [英] SceneKit camera, how to compensate for euler rules (orientation) changes

问题描述

也许这更像是一道数学题，但我希望有人能帮助我了解如何补偿相机方向的变化.

Maybe this is more of a math question, but I am hoping somebody can help me understand how I would compensate for changes to my camera's orientation.

我想做的是能够使用类似游戏的控件在场景中移动我的相机.我设置了 W S A D 键来分别向前、向后、向左和向右移动相机.我通过更改相机节点的位置向量的值来做到这一点.我还有右左上和下箭头键映射到转动和倾斜相机.我通过调整相机节点的欧拉规则(俯仰和偏航)来做到这一点.

What I would like to do is to be able to move my camera around the scene using game-like controls. I have W S A D keys set up to move the camera forward, backward, left and right respectively. I do this by changing the values of the camera node's position vector. I also have the right left up and down arrow keys mapped to turning and tilting the camera. I do this by adjusting the camera node's euler rules (pitch and yaw).

在我用左右箭头转动相机之前，一切正常.在此之后按 W 将相机移动到它在我对其应用偏航之前所面对的方向.这种行为对我来说很有意义，但我无法弄清楚我需要对位置矢量调整做什么来补偿我应用的偏航.

Things work well until I turn the camera with the right and left arrows. Pressing W after this moves the camera in the direction it was facing before I applied yaw to it. The behavior makes sense to me, but I cannot figure out what I need to do to my position-vector tweaking to compensate for the yaw I've applied.

我是否需要以某种方式将我的位置向量乘以新的变换?或者更好的是还有其他一些属性，比如我可以更改的枢轴，以便我可以保持我的位置代码相同?

Do I need to multiply my position vector somehow by new transform? Or better yet is there some other property like the pivot that I can change, so that I can keep my position code the same?

感谢您的任何指点.

这里更新的是我目前正在使用的代码:

Update here is the code I'm working with so far:

public func displayTimerDidFire(timer: MyCustomDisplayTimer!) {
    if timer === cameraMoveTimer {

        var cameraTransform = cameraNode.transform
        var x = CGFloat(0.0)
        var y = CGFloat(0.0)
        var z = CGFloat(0.0)

        var step : CGFloat = 10.0

        if moveUpKeyDown {
            y += step
        }
        if moveDownKeyDown {
            y -= step
        }
        if moveLeftKeyDown {
            x -= step
        }
        if moveRightKeyDown {
            x += step
        }
        if moveForwardKeyDown {
            z -= step
        }
        if moveBackwardKeyDown {
            z += step
        }

        cameraTransform = SCNMatrix4Translate(cameraTransform, x, y, z)
        cameraNode.transform = cameraTransform
    }
    else if timer === cameraTiltTimer {
        var angles = cameraNode.eulerAngles
        var stepAngle : CGFloat = CGFloat(M_PI_2 / 90.0)

        if turnLeftKeyDown {
            angles.y += stepAngle
        }
        if turnRightKeyDown {
            angles.y -= stepAngle
        }
        if tiltForwardKeyDown {
            angles.x -= stepAngle
        }
        if tiltBackwardKeyDown {
            angles.x += stepAngle
        }

        cameraNode.eulerAngles = angles
    }
}

我有两个计时器，一个更新相机位置，另一个更新其方向.

I have two timers, one that updates the cameras position, and the other that updates its orientation.

我坚持的部分是我知道我的新变换(旧位置加上 ASDW 的移动增量)，并且我知道相机的旋转，但我不知道如何将这两者结合到我真正的新变换中转变.Transform 是 SCNMatrix4，rotation 是 SCNVector4.

The part I'm stuck on is that I know my new transform (old position plus the move increment from A S D W), and I know the camera's rotation, but I don't know how to combine those two into my true new transform. Transform is a SCNMatrix4, and rotation is a SCNVector4.

更新 2

这是代码的修改版本.我改为使用转换.但是，我仍然找不到正确的操作来解释旋转.

Here is a reworked version of the code. I switched to working with the transform instead. I still cannot find the right manipulation to account for the rotation however.

public func displayTimerDidFire(timer: MyDisplayTimer!) {
    var cameraTransform = cameraNode.transform
    var x = CGFloat(0.0)
    var y = CGFloat(0.0)
    var z = CGFloat(0.0)

    var step : CGFloat = 10.0

    if moveUpKeyDown {
        y += step
    }
    if moveDownKeyDown {
        y -= step
    }
    if moveLeftKeyDown {
        x -= step
    }
    if moveRightKeyDown {
        x += step
    }
    if moveForwardKeyDown {
        z -= step
    }
    if moveBackwardKeyDown {
        z += step
    }

    cameraTransform = SCNMatrix4Translate(cameraTransform, x, y, z)
    // Do something with the transform to compensate for rotation..
    // ???

    cameraNode.transform = cameraTransform

    var angles = cameraNode.eulerAngles
    var stepAngle : CGFloat = CGFloat(M_PI_2 / 90.0)

    if turnLeftKeyDown {
        angles.y += stepAngle
    }
    if turnRightKeyDown {
        angles.y -= stepAngle
    }
    if tiltForwardKeyDown {
        angles.x -= stepAngle
    }
    if tiltBackwardKeyDown {
        angles.x += stepAngle
    }

    cameraNode.eulerAngles = angles
   // printNode(cameraNode)
}

<小时>

上次更新

---

Last Update

感谢您的建议.这是对我有用的实现

Thanks for the suggestions. Here is the implementation that is working for me

我需要这个 objc 助手，因为其中一些函数在 Swift 中似乎不可用:

I needed this objc helper, as some of these functions to not seem to be available in Swift:

@implementation MySceneKitUtils
+ (SCNVector3)position:(SCNVector3)position multipliedByRotation:(SCNVector4)rotation
{
    if (rotation.w == 0) {
        return position;
    }
    GLKVector3 gPosition = SCNVector3ToGLKVector3(position);
    GLKMatrix4 gRotation = GLKMatrix4MakeRotation(rotation.w, rotation.x, rotation.y, rotation.z);
    GLKVector3 r = GLKMatrix4MultiplyVector3(gRotation, gPosition);
    return SCNVector3FromGLKVector3(r);
}
@end

以及实现

public func displayTimerDidFire(timer: MyDisplayTimer!) {
    var x = CGFloat(0.0)
    var y = CGFloat(0.0)
    var z = CGFloat(0.0)

    var step : CGFloat = 10.0

    if moveUpKeyDown {
        y += step
    }
    if moveDownKeyDown {
        y -= step
    }
    if moveLeftKeyDown {
        x -= step
    }
    if moveRightKeyDown {
        x += step
    }
    if moveForwardKeyDown {
        z -= step
    }
    if moveBackwardKeyDown {
        z += step
    }

    var cameraTransform = cameraNode.transform
    var rotation = cameraNode.rotation
    var rotatedPosition = MySceneKitUtils.position(SCNVector3Make(x, y, z), multipliedByRotation: cameraNode.rotation)
    cameraTransform = SCNMatrix4Translate(cameraTransform, rotatedPosition.x, rotatedPosition.y, rotatedPosition.z)

    cameraNode.transform = cameraTransform

    // The rotation

    cameraTransform = cameraNode.transform
    var stepAngle = CGFloat(0.05)
    if turnLeftKeyDown {
        cameraTransform = SCNMatrix4Rotate(cameraTransform, stepAngle, 0.0, 1.0, 0.0);
    }
    if turnRightKeyDown {
        cameraTransform = SCNMatrix4Rotate(cameraTransform, -stepAngle, 0.0, 1.0, 0.0);
    }
    if tiltForwardKeyDown {
        cameraTransform = SCNMatrix4Rotate(cameraTransform, stepAngle, 1.0, 0.0, 0.0);
    }
    if tiltBackwardKeyDown {
        cameraTransform = SCNMatrix4Rotate(cameraTransform, -stepAngle, 1.0, 0.0, 0.0);
    }

    cameraNode.transform = cameraTransform
}

推荐答案

如果 t 是您从 WSAD 键计算的翻译，那么您不应该简单地添加它(node.position+= t) 但首先应用旋转然后添加它: node.position += node.rotation * t

if t is the translation you compute from the WSAD keys, then you should not simply add it (node.position += t) but first apply a rotation and then add it : node.position += node.rotation * t

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