How viewUp viewPlaneNormal work?

General
1

I have find oblique Volume Slice like this

case orientationOptions.oblique:
        // Some random oblique value for this dataset
        viewUp = [-0.5962687530844388, 0.5453181550345819, -0.5891448751239446];
        viewPlaneNormal = [
          -0.5962687530844388, 0.5453181550345819, -0.5891448751239446,
        ];

        viewport.setCamera({ viewUp, viewPlaneNormal });
        viewport.resetCamera();
        break;

I want to know how this two param（viewUp and viewPlaneNormal） work?
Any help?

2

I answered you on github