swift - simd_float4x4 列

Question

我想在不旋转图像的情况下平移平面。出于任何原因，我的图像正在旋转。

var translation = matrix_identity_float4x4
translation.colum = -0.2
let transform = simd_mul(currentFrame.camera.transform, translation)
planeNode.simdWorldTransform = matrix_multiply(currentFrame.camera.transform, translation)

此外，我注意到 matrix_identity_float4x4 包含 4 列，但文档不可用。

为什么是 4 列？有飞机的框架吗？

Answer 1

最简单的方法就是使用下面的代码进行定位:

let planeNode = SCNNode()
planeNode.geometry = SCNPlane(width: 20, height: 20)
// At first we need to rotate a plane about its x axis in radians:
planeNode.rotation = SCNVector4(1, 0, 0, -Double.pi/2)  
planeNode.geometry?.materials.first?.diffuse.contents = UIColor.red

planeNode.position.x = 10
planeNode.position.z = 10

// planeNode.position = SCNVector3(x: 10, y: 0, z: 10)

scene.rootNode.addChildNode(planeNode)

或者这样:

let cameraNode = SCNNode()
cameraNode.camera = SCNCamera()
cameraNode.position = SCNVector3(x: 0, y: 0, z: 15)
scene.rootNode.addChildNode(cameraNode)

let planeNode = SCNNode()
planeNode.geometry = SCNPlane(width: 20, height: 20)
planeNode.rotation = SCNVector4(1, 0, 0, -Double.pi/2)
planeNode.geometry?.materials.first?.diffuse.contents = UIColor.red

let distance: Float = 50
planeNode.simdPosition = cameraNode.simdWorldFront * distance  // -Z axis
planeNode.simdPosition = cameraNode.simdWorldRight * distance  // +X axis

scene.rootNode.addChildNode(planeNode)

If you wanna know more about matrices used in ARKit and SceneKit frameworks just look at Figure 1-8 Matrix configurations for common transformations.

希望这对您有所帮助。