fix stroke preview, use hmd pose instead of eye, fix vr fullscreen mode

src/hmd.cpp

@@ -201,7 +201,7 @@ void Vive::Draw()
         }
 
         if (on_draw)
-            on_draw(proj[eye], view[eye]);
+            on_draw(proj[eye], view[eye], mat_pose);
 
         eyes[eye].unbindFramebuffer();
     }