Modeling and Animation

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Modeling and Animation

• Lecture 5

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Physics Based Animation in 3DS Max

• Simulation User specifies objects, forces and
  processes to govern object and/or particle
  motion.
• Dynamic Space Warp Mechanism for specifying
  forces or constraints on motion of objects and/or
  particles.
• Path Follow, (PUS)dynaflect, (PUS)omniflect,
  (SU)deflector.
• Gravity, Wind, Push, Motor, Field, Pbomb, etc.
• Particle System Process that generates a
  collection of particles, with specified,
  randomized motion, over a region of space and a
  period of time
• (Super) Spray, Snow, Blizzard, PCloud, PArray.

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Example Max Files

• Dynamics
• A sphere falls under the influence of gravity and
  bounces off the floor bouncing-sphere.max
• One block falls and bounces while dangling from a
  damped spring attached to another block
  boxes-and-spring.max
• Particle Systems
• A stream of particles is emitted at a point and
  follows a spline path smoke-stack.max
• A stream of particles is emitted at a point, is
  blown by the wind, bounces off a wall and falls
  under the influence of gravity fountain.max

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Bouncing Sphere

• Create a small sphere in the ground plane.
• Go into Front View and pan vertically so you have
  room to watch the object fall downward.
• On the Command Panel, use Create, Space Warps,
  Particles and Dynamics to create a Gravity space
  warp in Top View.
• Check Front View to see that the arrow indicates
  a downward direction for gravity.

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Creating the Simulation

• Got to the Utilities tab on the Command Panel and
  click on Dynamics.
• Press New to create a new simulation, called
  Dynamics00.
• Press Edit Object List, select Sphere01 and use
  the gt button to include it in the simulation.
  Press OK to confirm.
• Press Edit Object and Assign Object Effects
  and use the gt button to include Gravity01 as an
  effect acting on Sphere01.

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Solve the Simulation

• Go to the Dynamics rollout on the Command Panel.
• Check the Update Display w/ Solve box.
• Press the Solve button The sphere accelerates
  downward, falling off the bottom of the window.
• Open Track View and look a the spheres Position
  track function curves.
• Notice that the curve is a parabola, described by
  lots of keys.
• Press Edit Time use the mouse to select the time
  range 0,100 and press Reduce Keys to reduce
  the number of keys.
• You may now edit this track as you wish.

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Adding Collisions

• Create a Box of size (W,L,H)(100,100,1) and
  location (x,y,z)(0,0,-100).
• Use Edit Object List on the Dynamics rollout on
  the Command Panel, to include Box01 in the
  Dynamics00 simulation.
• Press Edit Object, select Sphere01, press Assign
  Object Collisions and add Box01 to the
  collisions set for the sphere.
• Press Edit Object, select Box01 and check the box
  marked This object is unyielding under Dynamic
  Controls to make sure the box wont move.
• Press the Solve button and observe that the ball
  bounces.
• Go to track view to observe the function curves
  and reduce the number of keys, as before.

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Specification of Particle Systems

• Region of space over which particles are emitted.
  
• Period of time over which particles are emitted.
• Initial linear and rotational velocities of
  particles.
• Forces and/or process governing particles
  motion.
• Shape and material properties of particles.
• Lifetimes of particles.
• Probability distributions to specify randomness
  in any or all of the above.

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Fountain

• Use Create, Particle-Systems to create a Super
  Spray particle emitter in Perspective View at the
  center of the ground plane.
• Pull the Time Slide and see the particles that
  are emitted. Notice that no particles are emitted
  after the 30th frame.
• Use the Particle Generation rollout to arrange
  that particles are generated at a rage of 100 per
  second, over 100 frames and have a lifetime of
  100 frames.
• Increase the two Spread parameters in the Basic
  Parameters rollout to 45 degrees and 180.
• Pull the Time Slider again and observe the
  particle stream.

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Adding Wind

• Use Create, Space Warps, and Particles Dynamics
  on the Command Menu to create a Wind space warp
  in Left View.
• Use Bind Space Warp on the Main Toolbar to bind
  the Wind space warp to SuperSpray01.
• Notice that the particles are blown by the wind.

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Adding Gravity

• Use Create, Space Warps, and Particles Dynamics
  on the Command Menu to create a Gravity space
  warp in Left View.
• Set the Strength parameter of Gravity to 0.5
  units.
• Use Bind Space Warp on the Main Toolbar to bind
  the Gravity space warp to SuperSpray01.
• Notice that the particles are drawn downward by
  the Gravity.

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Adding a Deflector

• Use Create, Space Warps, and Particles Only on
  the Command Menu to create a POmniFlect space
  warp in Left View.
• Use Bind Space Warp on the Main Toolbar to bind
  the POmniFlect space warp to SuperSpray01.
• Rotate the POmniFlect space warp around the Y
  axis to deflect the particles upward.

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