Package jsim.collision

Class ContactPoint

java.lang.Object

jsim.collision.ContactPoint

public final class ContactPoint
extends Object

A single contact between two rigid bodies.

Convention: the contact normal points from body B toward body A (i.e. the direction body A is pushed to resolve the overlap). Penetration depth is positive when overlapping.

Field Summary

Fields

Modifier and Type	Field	Description
double	accumulatedNormalImpulse	Accumulated normal impulse for warm-starting (N·s), reset each tick.
double	accumulatedTangentImpulse	Accumulated tangent impulse magnitude (N·s).
RigidBody	bodyA	First body (the one pushed in the normal direction).
RigidBody	bodyB	Second body.
double	combinedFriction	Combined friction coefficient (dimensionless), filled in by the constraint builder.
double	combinedRestitution	Combined restitution coefficient (dimensionless), filled in by the constraint builder.
double	contactX	World-space contact point (midpoint of overlap region), in metres.
double	contactY	World-space contact point (midpoint of overlap region), in metres.
double	contactZ	World-space contact point (midpoint of overlap region), in metres.
double	normalX	World-space contact normal (unit vector, dimensionless, points A←B).
double	normalY	World-space contact normal (unit vector, dimensionless, points A←B).
double	normalZ	World-space contact normal (unit vector, dimensionless, points A←B).
double	penetration	Penetration depth (positive = overlapping), in metres.

Constructor Summary

Constructors

Constructor	Description
ContactPoint()	Creates an unpopulated contact point; call set(jsim.dynamics.RigidBody, jsim.dynamics.RigidBody, double, double, double, double, double, double, double) to fill it in.

Method Summary

Modifier and Type	Method	Description
void	set(RigidBody a, RigidBody b, double cx, double cy, double cz, double nx, double ny, double nz, double penetration)	Populate this contact with the given collision data.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

bodyA

public RigidBody bodyA

First body (the one pushed in the normal direction).

bodyB

public RigidBody bodyB

Second body.

contactX

public double contactX

World-space contact point (midpoint of overlap region), in metres.

contactY

public double contactY

World-space contact point (midpoint of overlap region), in metres.

contactZ

public double contactZ

World-space contact point (midpoint of overlap region), in metres.

normalX

public double normalX

World-space contact normal (unit vector, dimensionless, points A←B).

normalY

public double normalY

World-space contact normal (unit vector, dimensionless, points A←B).

normalZ

public double normalZ

World-space contact normal (unit vector, dimensionless, points A←B).

penetration

public double penetration

Penetration depth (positive = overlapping), in metres.

combinedFriction

public double combinedFriction

Combined friction coefficient (dimensionless), filled in by the constraint builder.

combinedRestitution

public double combinedRestitution

Combined restitution coefficient (dimensionless), filled in by the constraint builder.

accumulatedNormalImpulse

public double accumulatedNormalImpulse

Accumulated normal impulse for warm-starting (N·s), reset each tick.

accumulatedTangentImpulse

public double accumulatedTangentImpulse

Accumulated tangent impulse magnitude (N·s).

Constructor Details

ContactPoint

public ContactPoint()

Creates an unpopulated contact point; call set(jsim.dynamics.RigidBody, jsim.dynamics.RigidBody, double, double, double, double, double, double, double) to fill it in.

Method Details

set

public void set(RigidBody a,
 RigidBody b,
 double cx,
 double cy,
 double cz,
 double nx,
 double ny,
 double nz,
 double penetration)

Populate this contact with the given collision data.

Parameters:

a - first body

b - second body

cx - contact point X (metres)

cy - contact point Y (metres)

cz - contact point Z (metres)

nx - contact normal X (unit vector)

ny - contact normal Y (unit vector)

nz - contact normal Z (unit vector)

penetration - overlap depth (positive = overlapping, metres)