Create a camera from position, direction, and an optional X-axis.
If xAxis is omitted, it is derived automatically from the direction.
xAxis
Camera position in world coordinates.
View direction (camera looks along this vector).
Optional
Optional horizontal axis; derived automatically if not provided.
Result<Camera> -- an error if direction is zero-length.
Result<Camera>
Create a camera from position, direction, and an optional X-axis.
If
xAxisis omitted, it is derived automatically from the direction.