Switching projection matrix?

strong texti wan to move from unity world space to my device camera space?

This is not related to the projection matrix. The projection matrix controls how points are converted to the unit cube, also known as clip space, during the final stage of the transformation pipeline. Camera space is the stage just prior to that. The full order is:

Model space → World space → Camera space → Clip space

The transitions are done using matrix multiplications. Model->World is the model matrix, World->Camera is the view matrix and camera → clip is the projection matrix. When concatenated, they become the “ModelViewProjection” matrix, or sometimes “MVP” for short.

If you want to transform a point from world space to camera space, you need to multiply it by the view matrix. In Unity, the camera’s view matrix is available through Camera.worldToCameraMatrix.

This transforms a point in world coordinates to that camera’s local space.