jump

1. Square ascends at upSpeed until just before targetHT is reached
2. Right before targetHT is reached (90% of targetHT?), upSpeed slows dramatically, becoming finalUpSpeed
3. Once targetHT is reached, before falling back to the ground, square will pause and hover very briefly
4. This simulates the effect of gravity taking over after the upward force has been expended

TargetHT determined by buttonPressDuration

• Minimum targetHT is 100px from ground.
• Maximum targetHT is 300px from ground.
• What is upSpeed?
  • What % of upSpeed is finalUpSpeed?
• What is downSpeed?
  • downSpeed is constant
• Are upSpeed/downSpeed the same?
• If not, which is greater?
• (actually, downSpeed should be greater)
  • Min speed is 1 ms, so is this even possible?
  • (maybe decrement squareTop by more than 1px)

handleJumpButton()

• if jump already in progress, return/handle appropriately
• else set state jumping boolean to true
• determine targetHT based on buttonPressDuration
• invoke handleJumpPhysics(targetHT)

handleButtonDuration()

• Stop buttonTimer

handleJumpPhysics(tH)

• send square up at upSpeed until 90% of targetHT reached
• reduce upSpeed to finalUpSpeed until targetHT reached
• pause, letting square hover briefly
  • (a few milliseconds or so at most)
• send square down at downSpeed
• reset state buttonPressDuration to 0
• set state jumping boolean to false