unitycoder

UNITY_MATRIX_IT_MV[0].xyz = ???
UNITY_MATRIX_IT_MV[1].xyz = Camera Up
UNITY_MATRIX_IT_MV[2].xyz = Camera Forward

float3 forward = -normalize(UNITY_MATRIX_V._m20_m21_m22);
float3 up = normalize(UNITY_MATRIX_V._m10_m11_m12);
float3 right = normalize(UNITY_MATRIX_V._m00_m01_m02);

float3 cameraUp = unity_CameraInvProjection[1].xyz;
float3 camRight = cross(unity_CameraInvProjection[2].xyz, cameraUp);

Dan-Piker

//Moebius transformations in 3d, by reverse stereographic projection to the 3-sphere,
//rotation in 4d space, and projection back.
//by Daniel Piker 09/08/20
//Feel free to use, adapt and reshare. I'd appreciate a mention if you post something using this.
//You can also now find this transformation as a component in Grasshopper/Rhino
//I first wrote about these transformations here:
//https://spacesymmetrystructure.wordpress.com/2008/12/11/4-dimensional-rotations/

//If you want to transform about a given circle. Points on the circle and its axis stay on those curves.
//You can skip these 2 lines if you want to always use the origin centred unit circle.