Matrix for AR

matrixAR.swift

projectionMatrix = arCameraData.projectionMatrix
viewMatrix = arCameraData.viewMatrix



var floorDepthMap : [Float] = []
if let tempDepthMap = groundPlaneDepthMap {
    floorDepthMap = tempDepthMap
}

if let segmentationInstance = segmentationFrameData?.instance(forPersonId: person.personId) {
                    boundingBoxBottomMidpoint = float2(x: Float(segmentationInstance.center.x), y: Float(segmentationInstance.maxY))
                    segId = Int(segmentationInstance.segmentationId)
}


/// Sample our depth map
let depthMapIndex = boundingBoxBottomMidpoint.x + boundingBoxBottomMidpoint.y * Float(octi.videoSize.width)

if let tempDepthVal = floorDepthMap[safe: Int(depthMapIndex)] {
    depthVal = tempDepthVal
}

let worldPos: float3 = ARFloorFinder.screenToWorld(screenPoint: CGPoint(x: CGFloat(boundingBoxBottomMidpoint.x), y: CGFloat(boundingBoxBottomMidpoint.y)),
                                                           zDepth: depthVal,
                                                           screenSize: videoSize,
                                                           projectionMatrix: projectionMatrix,
                                                           viewMatrix: viewMatrix)
                                                           
var modelMatrix = matrix_identity_float4x4
modelMatrix = modelMatrix.translatedBy(x: worldPos.x, y: worldPos.y, z: worldPos.z)

if billboard {
    modelMatrix = modelMatrix.rotatedBy(rotationAngle: -arCameraData.eulerAngles.y, x: 0, y: 1, z: 0)
}

modelMatrix = modelMatrix.scaledBy(x: modelWorldSize.x, y: modelWorldSize.y, z: 1)

let modelViewProjectionMatrix = projectionMatrix * viewMatrix * modelMatrix