几个坐标的解释,UNITY_MATRIX_MV, _Object2World,UNITY_MATRIX_MVP

1. World Matrix - Transforms 3D data from Model Space into World Space. You need to set this before rendering every entity in your world.
2. View Matrix - Transforms from World Space into View Space. You need to set this each time your camera changes position
3. Projection Matrix - Transforms from View Space into Screen Space. You normally set this just once during initialization.