Integration
// From a tutor engine or host page:
frame.contentWindow.postMessage(
{type: "state", state: "EXPLAINING"}, "*");
// Or in this page:
teacher.handle({type: "look", target: "x_squared"});
teacher.handle({type: "board", command:
{action: "HIGHLIGHT", target: "x_squared"}});
Event types: state, gesture, say, look, turn, face, board, camera, caption. Same schema as the Blender runtime.