Add all_cars_in_dragway python demo; Remove C++ automotive_demo

[apojomovsky]

Fixes the first item of the first list in #378

• Removes the demo_launcher.py as well as the automotive_demo.cc.
• Adds the all_cars_in_dragway python demo, with the same basic functionality as the pair demo_launcher + automotive_demo.

Missing:

• A trajectory-car for the demo. We might need to bind or at least mimic the functionality found in drake's CreateTrajectoryParams function, in order to generate the parameters for the car.

[basicNew]

@stonier just to double check: last time we spoke about python bindings I recall we decided not to work on the trajectory car, as that was (is?) undergoing a refactoring in drake. As we port this demo from C++ to port we would remove the last demo that showed that car. Is that ok? Want me to add an issue for milestone 3 to bring it back?

[basicNew]

Thanks @apojomovsky , just left a comment about refactoring car-creation functions.

[basicNew]

I know this is not specific of this issue, but seems like a good time to do it. Could you please move this functions to simulation_utils.py and make them parametrizable? Then you could use them in loadable_agent_simulation.py and railcar_in_multilane.py (as well as refactoring the build_simple_car_simulator in simulation_utils.py).

[apojomovsky]

sounds good! done!

[hidmic]

Just a couple nit-picks. Overall looks great!

[hidmic]

@apojomovsky here and below, typo instanciates -> instantiates.

[apojomovsky]

oops, thanks! done!

[hidmic]

@apojomovsky Instantiate -> Instantiates

[apojomovsky]

sorry for that, fixed!

[apojomovsky]

Thanks for the review @basicNew and @hidmic , I just finished addressing your comments. Could you PTAL?

[stonier]

Some minor things:

• get the generate_python_docs.sh to populate items in alphabetical order
• do we still need loadable_agent_simulation.py? The all_cars_in_dragway` should provide demo coverage (for the cars at least, should still have something for non-road, dragway, multilane variations)
• fix conflicts from recent merge of [infra] python un-nested #391
• update python_examples.md.template.in to point to the delphyne guide for installation instructions
• update the delphyne guide to point to the all_cars_in_dragway instead of the demo_launcher as the defacto example

The add_xyz() scripts are very useful! I'll let @hidmic confirm the review.

[stonier]

@stonier just to double check: last time we spoke about python bindings I recall we decided not to work on the trajectory car, as that was (is?) undergoing a refactoring in drake. As we port this demo from C++ to port we would remove the last demo that showed that car. Is that ok? Want me to add an issue for milestone 3 to bring it back?

Yes, a new trajectory agent just went into Drake. Mostly RobotLocomotion/drake#8720 and RobotLocomotion/drake#8725. I'll probably play with them as I do this 'has-a' relationship between delphyne loadable wrappers and Drake agents.

[basicNew]

Ack, thanks for the heads-up @stonier on new trajectory agents in Drake.

[apojomovsky]

Thanks for you feedback @stonier ! I just finished addressing your comments.
Regarding the loadable_agent_simulation.py, you're right that it's not needed anymore, so I just removed it. As per multilane road, and since we already have the railcar_in_multilane.py around, do you think we should add another demo?

[stonier]

Should at least have something that tickles the possibility of loading without roads (~ loadable_agents_demo with simple car previously). If that's just in as a test, that's also fine - i.e. doesn't have to be a demo.

[apojomovsky]

There are a couple of demos that already exercises this no-road functionality: time_bounded_simulation, start_simulation_paused, keyboard_controlled_demo, among others. Adding this as an option for this demo would involve having only a simple car on stage, so I'd chose to leave this particular demo as is. What do you think @stonier ?

[stonier]

Agreed