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/* _____ _ __ ________ ___ *\
** / ___/(_) |/ / ___/ |__ \ Simple Mechanics Simulator 2 **
** \__ \/ / /|_/ /\__ \ __/ / copyright (c) 2011 Jakob Odersky **
** ___/ / / / / /___/ / / __/ **
** /____/_/_/ /_//____/ /____/ **
\* */
package sims.dynamics
import sims.dynamics._
import sims.dynamics.constraints._
import sims.collision.{Collision => CCollision}
/** A class representing a physical collision,
* implementing constraints to handle collision response. */
class Collision(collision: CCollision[Shape]) extends Constraining {
private def getNonPenetrationConstraints() = for (point <- collision.points) yield
new Constraint {
val body1 = collision.item1.body
val body2 = collision.item2.body
def v = body2.velocityOfPoint(point) - body1.velocityOfPoint(point)
val e = {
if ((v dot collision.normal.unit) > 0) 0.0
else if ((v dot collision.normal.unit) > -1) 0.0
else math.min(collision.item1.restitution, collision.item2.restitution)
}
def jacobian = new Jacobian(-collision.normal, -((point - body1.position) cross collision.normal),
collision.normal, ((point - body2.position) cross collision.normal))
override def bias = (v dot collision.normal.unit) * e
def value = -collision.overlap
override def inequality = true
override val limit = Some((0.0, Double.PositiveInfinity))
val slop = 0.005
override def error =
if (collision.overlap > slop)
-(collision.overlap - slop)
else 0.0
}
val constraints = getNonPenetrationConstraints()
}
object Collision {
/**Converts a collision to a physical collision
* (sims.collision.Collision to a sims.dynamics.Collision)*/
implicit def collision2Physical(c: sims.collision.Collision[Shape]) = new Collision(c)
implicit def collision2Constructor(c: sims.collision.Collision[Shape]) = new { def toPhysical = new Collision(c) }
}
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