Before making the final AR avatar, I made a test version. Because I wanted to try out the effect I envisaged first to see if it would work. With what I learned in class on how to make the 3d glasses model track to the face and some tutorials I learned on the YouTube I made the following test version of the split face.
First, I create a face tracker, then add five face meshes 01234 underneath them, at the same time create five materials 01234, then assign the materials to each face meshes by number, then set the material map for 1234 to face tracking and the material for 0 to black because I like to create a sense that the original face is missing.
After that I drew four png layers in photoshop that divided a canvas into four parts（The black parts are transparent layers）
Then I put each of the four png images into the alpha setting（a control that masks the alpha chennel of texture） of the 1234 material, so that the face is divided equally into four parts.
After that, I moved the four face meshes to the position I wanted, by moving and rotating them (the rotation in the SparkAR is very difficult to use I don’t know how to set the coordinate system to the position I want instead of the world or object coordinate,and in blender there is this very good function for moving cursors)
Final result