Writing Custom Gizmos

The following skeleton code shows how gizmo behaviors typically work:

Context& ctx = GetContext();
const AppData& appData = ctx.getAppData();
Ray ray(appData.m_cursorRayOrigin, appData.m_cursorRayDirection);
float intersectionDepth;
bool intersects = // intersect ray with the gizmo primitive and get intersectionDepth
Vec3 intersection = ray.m_origin + ray.m_direction * intersectionDepth; // world space intersection

if (gizmoId == ctx.getActiveId()) {  // gizmo is active
	if (ctx.isKeyDown(Action_Select)) {
	  // interaction is ongoing, update outputs, etc.
	} else {
	  // interaction stopped, deactivate the gizmo (return to a hot state)
		ctx.setActiveId(Id_Invalid);
	}

} else if (gizmoId == ctx.getHotId()) {  // gizmo is hot
	if (intersects) {
	 // hot state is valid, can make active
		if (ctx.isKeyDown(Action_Select)) {
			ctx.setActiveId(gizmoId);
		}
	} else {
	 // return to a cold state
		ctx.resetId();
	}

} else {  // gimo is cold
	ctx.makeHot(gizmoId, intersectionDepth, intersects);
}