ARTC 312  The Classic Ball Bounce Assignment 1   Dena Eber

 

Due Tuesday, September 10      Playblast of Ball Bounce Animation

 

For Thursday, August 29

Bring an assortment of balls to class, rubber balls, deflated balls, superballs, etc.

Review the following urls:

For Conceptual Help, See:

ballbounce physics 1

http://rabi.phys.virginia.edu/HTW//bouncing_balls.html

 

ballbounce physics 2

http://electron4.phys.utk.edu/141/sep26/September26.html

 

Ball Bounce Example:

http://www.rsad.edu/~jkennedy/SchoolCAbounce.shtml

 

Rules:

  1. At least 2 balls, with different characteristics must be used.
  2. Laws of the real-world and of physics apply. Balls may not sprout wings, morph into pacmen, or become autonomous characters.
  3. Balls must effect at least two other objects (not counting the walls and floors)
  4. NO Camera cuts.

 

In Class Exercise:

The Classic Ball bounce:

 

  1. Make plane and ball
  2. Scale Plane and position Ball on far left of plane (-x)
  3. Group Ball to itself 3 times
  4. Name each Node in the Outliner (order is important)

 

TransBall

ScaleBall

RotateBall

 

  1. Modify -> Center Pivot for each group node
  2. In Channels set key on Translate X on the TransBall Group on Frame 1
  3. Frame 60 move ball to other end of plane and set key on X on TransBall
  4. Move to Frame 30 and set key frame
  5. Frame 1, 30, and 60  set key on TransBall Y(with Ball on floor)
  6. Frame 15 and Frame 45 set key on Y with Ball up in the air

 

In Graph Editor:

  1. Select View->Frame All
  2. Select all bottom keyframes on the Y curve
  3. Break the tangents (Keys->Break) and Free the weight (Keys->Free Tangent)
  4. Adjust Tangents so the ball hits the ground fast (MM Drag manipulator)
  5. Make sure second bounce is not as high as first bounce.
  6. Edit -> Copy the Frame 30 Translate X key
  7. Go to frame 31 in Timeline, return to Graph Editor, and select Edit->Paste
  8. Go to frame 29 in Timeline, return to Graph Editor, and select Edi->Paste
  9. In the Graph Editor, copy Value in 2nd Stats Box, frame 29, into 2nd Stats Boxes
  10. For frames 30 and 31.
  11. Marque-Select keyframes 29,30 and 31 for the Translate X
  12. Go to Tangent -> In Tangent Linear.

 

In the Outliner:

  1. Select the Scale Node and move Pivot to the bottom of the ball (INSERT (HOME on Mac) key ON then OFF)
  2. At Frame 15, Select All Three ScaleBall Nodes in Channel Box, RMB and Key Selected
  3. Repeat above step for frame 45.
  4. At Frame 1 scale the ball down on Y and set key on ScaleBall on the Y.
  5. MMB Drag to Frame  30 in Timeline, and set Key, repeat for Frame 60.
  6. At Frames 5, 29, 35, and 59 scale the ball to 1 and set keys on XYZ.  (Easiest to set first)
  7. One, then MMB Drag in Timeline to next and set key.

 

Adjust Volume:

 

  1. On Frame 1, 30 and 60 adjust the X and Z scaling to maintain equal volume and set keys on scale X and Z

 

Rotate the Ball:

 

  1. See if you can get the ball to Rotate using the RotateBall Node (only two key frames are needed)
  2. Make the ball bounce in half the time –
  3. Shift select the 3 nodes in the Outliner

 

Stretching key frames - scaling

 

In Graph Editor:

 

  1. Select All the Nodes in the Outliner
  2. In the Graph Editor - View Frame All
  3. Select All nodes
  4. Edit ->Scale Options
  5. Select Start-End method, enter in New Start/End Times, hit Enter
  6. Click Scale Keys
  7. Remember to change the end time on the time slider

 

 

Problems for you to solve:

 

  1. Ball should stop rotation when it touches the ground.  Can you fix it?
  2. Ball’s rotation rate would decrease, can you fix that?
  3. Balls with different properties will bounce differently, use different kinds of balls.