I want to add FrontImage and BackImage in signal/roadsign's desc.
For one-way roadsign and signals (especially for driving-left), Front/Back image can be wrong.
In addition, why does signal_t::calc_image() not use roadsign_desc_t::ONLY_BACKIMAGE?
It has been suggest ed before. But signals have back and foregroundimages already. The problem with explicitely defined front and backimage is that it
1) they have to swap somewhat on switching left side and right side driving (current code should do this)
2) they have to be backward compatible
3) any new system should be able to deal with also with switches
The roadsign_desc_t::ONLY_BACKIMAGE is no neede since when offset_left=0, the signal is not to be shifted and thus the right side rules should apply (unless there is an error in the routines).