1. Particle Systems

2. Particle Systems dust stars people in a crowd hair (keep path)
Wikipedia: Particle Systems

3. particle2.c
link on webpage
options are in menu

4. Angel: Interactive Computer Graphics 5E © Addison-Wesley 2009
Newtonian Particle
Particle system is a set of particles
Each particle is an ideal point mass
Six degrees of freedom
Position
Velocity
Each particle obeys Newtons’ law
f = ma 4
Angel: Interactive Computer Graphics 5E © Addison-Wesley 2009

5. Angel: Interactive Computer Graphics 5E © Addison-Wesley 2009
Particle Equations
pi = (xi, yi zi)
vi = dpi /dt = pi' = (dxi /dt, dyi /dt , dzi /dt)
m vi'= fi
Hard part is defining force vector 5
Angel: Interactive Computer Graphics 5E © Addison-Wesley 2009

6. Force Vector Independent Particles Coupled Particles O(n)
Gravity
Wind forces
O(n) calulation
Coupled Particles O(n)
Meshes
Spring-Mass Systems
Coupled Particles O(n2)
Attractive and repulsive forces

7. Angel: Interactive Computer Graphics 5E © Addison-Wesley 2009
Collisions
Once we detect a collision, we can calculate new path
Use coefficient of resititution
Reflect vertical component
May have to use partial time step 7
Angel: Interactive Computer Graphics 5E © Addison-Wesley 2009

8. Angel: Interactive Computer Graphics 5E © Addison-Wesley 2009
Meshes
Connect each particle to its closest neighbors
O(n) force calculation
Use spring-mass system 8
Angel: Interactive Computer Graphics 5E © Addison-Wesley 2009

9. falling beam then melting on hot surface (from thesis David Love Tonnesen)

11. draping cloth from same thesis