fix clock speed in car mode

[zimmy87]

Fixes: #4241
Fixes: #4232

About

The car mode currently utilizes a default clock for returning the CarState's timestamp, so the clock speed from the settings isn't reflected in the timestamp. This change adds logic for initializing the appropriate clock type from settings as well as logic for reading the timestamp from the newly initialized clock.

How Has This Been Tested?

The following script was used in car mode to confirm the clock was advancing at the proper clock speed. This script outputs the delta of the simulation clock after 1 real-world second elapses. If everything is working correctly, this script should output the same value as the ClockSpeed in the settings:

import setup_path 
import airsim

import pprint
import time

# connect to the AirSim simulator 
#client = airsim.MultirotorClient()
client = airsim.CarClient()
client.confirmConnection()
client.enableApiControl(True)

#prev = client.getMultirotorState().timestamp
prev = client.getCarState().timestamp
curr = prev
print(prev)
while True:
    #curr = client.getMultirotorState().timestamp
    curr = client.getCarState().timestamp
    delta = curr - prev
    prev = curr
    print(delta / 1000000000)
    time.sleep(1.0)

client.enableApiControl(False)

Screenshots (if appropriate):

[rhalaly]

Does it also support pause and resume? If the simulation is paused for 10 seconds, will the timestamp be the same?

[jonyMarino]

Thanks @zimmy87 !!!

[zimmy87]

Hi @rhalaly, thank you for taking a look at this PR. From testing locally with pause_continue_car.py, it looks like the new clock does respond to pause and resume commands correctly.