import pybullet as p
import pybullet_data
import time

p.connect(p.GUI)
p.setAdditionalSearchPath(pybullet_data.getDataPath())
p.loadSDF("stadium.sdf")
p.setGravity(0, 0, -10)
objects = p.loadMJCF("mjcf/sphere.xml")
sphere = objects[0]
p.resetBasePositionAndOrientation(sphere, [0, 0, 1], [0, 0, 0, 1])
p.changeDynamics(sphere, -1, linearDamping=0.9)
p.changeVisualShape(sphere, -1, rgbaColor=[1, 0, 0, 1])
forward = 0
turn = 0

forwardVec = [2, 0, 0]
cameraDistance = 1
cameraYaw = 35
cameraPitch = -35

while (1):

  spherePos, orn = p.getBasePositionAndOrientation(sphere)

  cameraTargetPosition = spherePos
  p.resetDebugVisualizerCamera(cameraDistance, cameraYaw, cameraPitch, cameraTargetPosition)
  camInfo = p.getDebugVisualizerCamera()
  camForward = camInfo[5]

  keys = p.getKeyboardEvents()
  for k, v in keys.items():

    if (k == p.B3G_RIGHT_ARROW and (v & p.KEY_WAS_TRIGGERED)):
      turn = -0.5
    if (k == p.B3G_RIGHT_ARROW and (v & p.KEY_WAS_RELEASED)):
      turn = 0
    if (k == p.B3G_LEFT_ARROW and (v & p.KEY_WAS_TRIGGERED)):
      turn = 0.5
    if (k == p.B3G_LEFT_ARROW and (v & p.KEY_WAS_RELEASED)):
      turn = 0

    if (k == p.B3G_UP_ARROW and (v & p.KEY_WAS_TRIGGERED)):
      forward = 1
    if (k == p.B3G_UP_ARROW and (v & p.KEY_WAS_RELEASED)):
      forward = 0
    if (k == p.B3G_DOWN_ARROW and (v & p.KEY_WAS_TRIGGERED)):
      forward = -1
    if (k == p.B3G_DOWN_ARROW and (v & p.KEY_WAS_RELEASED)):
      forward = 0

  force = [forward * camForward[0], forward * camForward[1], 0]
  cameraYaw = cameraYaw + turn

  if (forward):
    p.applyExternalForce(sphere, -1, force, spherePos, flags=p.WORLD_FRAME)

  p.stepSimulation()
  time.sleep(1. / 240.)
