Speed Velocity, Acceleration and Deceleration:

To run the program

• Program: Click here to download/run the program. Here is the source code to this program (download and unzip).
• How to run:
  • Left-Mouse-Button (LMB) click define the guide ball (G_p). The direction for the hero velocity (V) is defined to be from current hero center (H_p) towards the guide ball (G_p).
  • LMB-Drag distance defines the speed (S) for the velocity.
• What:
  • The hero ball shoots toward the guide ball accelerating by 5% of current speed.
  • When the hero speed exceeds 1000 pixels/second, a deceleration of 90% of current speed is applied to stop the hero ball.

Implementation:

• Direction of hero Velocity: from Hero towards guid ball.
  • V = (G_p - H_p).Normalize() (Normaliize: to get unit vector for direction.)
  • Implementation: WindowHandler::OnMouseButton() function: lines 93 and 94.

   

• Speed for hero Velocity: distance between guide ball position (G_p) and current mouse position (M_p).
  • S = Length(M_p - G_p).
  • Implementation: WindowHandler::OnMouseButton() function: line 92.
  • Setting the hero velocity (S * V) to hero: lines 95 and 96.

   

• Acceleration for hero Velocity: increase by 5% of current speed.
  • CurrentSpeed = Length(Hero.Velocity)
  • Hero.Velocity = CurrentSpeed * 1.05 * Normalize(Hero.Velocity)
  • Implementation: Model::UpdateABall() function:
    • Line 40: Compute CurrentSpeed.
    • Lines 41 and 48: sets Hero.Velocity

     

• Deceleration for hero Velocity: when current hero speed exceed 1000 pixel/sec, begin decelerate by 90% of current speed until stops.
  • CurrentSpeed = Length(Hero.Velocity), check CurrentSpeed against 1000.
  • If too fast, set acceration to 0.9.
  • Hero.Velocity = CurrentSpeed * 0.9 * Normalize(Hero.Velocity)
  • Implementation: Model::UpdateABall() function:
    • Line 42: check CurrentSpeed for beginning of deceleration.
    • Lines 45 and 46: sets acceleration to be slowing down.