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/* _____ _ __ ________ ___ *\
** / ___/(_) |/ / ___/ |__ \ Simple Mechanics Simulator 2 **
** \__ \/ / /|_/ /\__ \ __/ / copyright (c) 2011 Jakob Odersky **
** ___/ / / / / /___/ / / __/ **
** /____/_/_/ /_//____/ /____/ **
\* */
package sims.dynamics
import sims.dynamics.constraints._
import sims.math._
/** A revolute joint, used to keep two bodies fixed relatively at one point.
*
* This joint removes two degrees of freedom between two bodies,
* hence it contains two [[sims.dynamics.constraints.Constraint]]s.
*
* @param body1 first body connected by this joint
* @param body2 second body connected by this joint
* @param anchor anchor point where bodies are fixed relatively */
class RevoluteJoint(val body1: Body, val body2: Body, val anchor: Vector2D) extends Joint {
def this(body1: Body, body2: Body) = this(body1, body2, body1.position)
private val self = this
private val local1 = anchor - body1.position
private val local2 = anchor - body2.position
private val rotation01 = body1.rotation
private val rotation02 = body2.rotation
def r1 = (local1 rotate (body1.rotation - rotation01))
def r2 = (local2 rotate (body2.rotation - rotation02))
def x1 = body1.position + r1
def x2 = body2.position + r2
def x = x2 - x1
val constraints = List(
new Constraint {
val body1 = self.body1
val body2 = self.body2
def value = x.x
def jacobian = new Jacobian(-Vector2D(1, 0), r1.y, Vector2D(1, 0), -r2.y)
},
new Constraint {
val body1 = self.body1
val body2 = self.body2
def value = x.y
def jacobian = new Jacobian(-Vector2D(0, 1), -r1.x, Vector2D(0, 1), r2.x)
}
)
}
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