CSE 683: Lab #77
tentatively Due Monday, Nov. 15

LAB 7: Spring-mass-damper mesh flag

Implement a 10x10 spring-mass-damper mesh to simulate a flag: the mesh should be in the x-y plane. Fix the leftmost vertices in space. Implement gravity and a pseudo-random wind field as global forces.

Getting a spring-damper system to behave the way you want it to requires trial-and-error to set the appropriate values for time-delta, mass, spring constant, damper constant, and wind strength.

Suggestions:

• code it so you can easily change the resolution of the 'cloth' (helps to use low-res cloth when debugging)
• display with a checkerboard pattern - alternate colors for each grid of cloth, or some other interesting pattern of your choice.
• each vertex has the following attributes:
  • mass
  • current position
  • current velocity
  • accumulated force
  • 'fixed' flag (set if this vertex is not allowed to move)
  each spring has the following attributes:
  • pointer to the two masses it attaches to
  • spring constant
  • damper constant
  • rest length (length in original configuration, for example)
  use following pseudo-code

  for each mass, set force to gravity + wind field
  for each spring, compute force and add to masses' force (one +f, one -f)
  for each mass, if not fixed, compute acceleration from force and update velocity and position
  

Extra Credit:

• compare simulations:
  • with and without diagonal springs
  • with and without angular springs
• map a really interesting texture onto the cloth
• animate the fixed points to create interesting animation
• try clamping the length of a spring and/or the spring length velocity for more robust cloth