All Implemented Interfaces:

Copyable<Mass>
```
public class Mass
extends Object
implements Copyable<Mass>
```
Represents Mass data for an object about a given point.
Stores the center of mass, the mass, and inertia.
The center point may be something other than the origin (0, 0). In this case, the mass and inertia are about this point, not the origin.
A Mass can also take on special MassTypes. These mass types allow for interesting effects during interaction.
When the mass type is changed, the original mass and inertia values are not lost. This allows the swapping of mass types without recomputing the mass.

Since:

1.0.0

Version:

5.0.0

Author:

William Bittle

See Also:

MassType

Constructor Summary

Constructors
Constructor	Description
`Mass()`	Default constructor.
`Mass(Mass mass)`	Copy constructor.
`Mass(Vector2 center, double mass, double inertia)`	Full Constructor.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`Mass`	`copy()`	Returns a deep copy of this object.
`static Mass`	`create(List<Mass> masses)`	Creates a `Mass` object from the given array of masses.
`boolean`	`equals(Object other)`
`Vector2`	`getCenter()`	Returns the center of mass.
`double`	`getInertia()`	Returns the inertia tensor.
`double`	`getInverseInertia()`	Returns the inverse inertia tensor.
`double`	`getInverseMass()`	Returns the inverse mass.
`double`	`getMass()`	Returns the mass.
`MassType`	`getType()`	Returns the mass type.
`int`	`hashCode()`
`boolean`	`isInfinite()`	Returns true if this `Mass` object is of type `MassType.INFINITE`.
`void`	`setType(MassType type)`	Sets the mass type.
`String`	`toString()`

Methods inherited from class Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - Mass
```
public Mass()
```
    Default constructor.
    Creates an infinite mass centered at the origin.
  - Mass
```
public Mass(Vector2 center,
            double mass,
            double inertia)
```
    Full Constructor.
    The center parameter will be copied.
    
    Parameters:
    
    center - center of Mass in local coordinates
    
    mass - mass in kg
    
    inertia - inertia tensor in kg · m²
    
    Throws:
    
    NullPointerException - if center is null
    
    IllegalArgumentException - if mass or inertia is less than zero
  - Mass
```
public Mass(Mass mass)
```
    Copy constructor.
    Performs a deep copy.
    
    Parameters:
    
    mass - the Mass to copy
    
    Throws:
    
    NullPointerException - if mass is null
- Method Detail
  - copy
```
public Mass copy()
```
    Description copied from interface: Copyable
    
    Returns a deep copy of this object.
    
    Specified by:
    
    copy in interface Copyable<Mass>
    
    Returns:
    
    T
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - equals
```
public boolean equals(Object other)
```
    Overrides:
    
    equals in class Object
  - create
```
public static Mass create(List<Mass> masses)
```
    Creates a Mass object from the given array of masses.
    Uses the Parallel Axis Theorem to obtain the inertia tensor about the center of all the given masses:
    I_dis = I_cm + mr² I_total = ∑ I_dis
    The center for the resulting mass will be a mass weighted center.
    This method will produce unexpected results if any mass contained in the list is infinite.
    
    Parameters:
    
    masses - the list of Mass objects to combine
    
    Returns:
    
    Mass the combined Mass
    
    Throws:
    
    NullPointerException - if masses is null or contains null elements
    
    IllegalArgumentException - if masses is empty
  - isInfinite
```
public boolean isInfinite()
```
    Returns true if this Mass object is of type MassType.INFINITE.
    A mass will still be treated as an infinite mass in physical modeling if the mass and inertia are zero. This method simply checks the mass type.
    
    Returns:
    
    boolean
  - setType
```
public void setType(MassType type)
```
    Sets the mass type.
    NOTE: This method will only set the MassType when it's valid to do so. The following logic describes this:
    
    The given type is MassType.NORMAL and both the mass and inertia are non-zero
    
    The given type is MassType.FIXED_LINEAR_VELOCITY and inertia is non-zero
    
    The given type is MassType.FIXED_ANGULAR_VELOCITY and the mass is non-zero
    
    Otherwise, the operation will be ignored and the current mass type left as is.
    Parameters:
    
    type - the mass type
    
    Throws:
    
    NullPointerException - if type is null
  - getType
```
public MassType getType()
```
    Returns the mass type.
    
    Returns:
    
    MassType
  - getCenter
```
public Vector2 getCenter()
```
    Returns the center of mass.
    
    Returns:
    
    Vector2
  - getMass
```
public double getMass()
```
    Returns the mass.
    NOTE: if this mass is type MassType.INFINITE or MassType.FIXED_LINEAR_VELOCITY this method returns zero.
    
    Returns:
    
    double
  - getInertia
```
public double getInertia()
```
    Returns the inertia tensor.
    NOTE: if this mass is type MassType.INFINITE or MassType.FIXED_ANGULAR_VELOCITY this method returns zero.
    
    Returns:
    
    double
  - getInverseMass
```
public double getInverseMass()
```
    Returns the inverse mass.
    NOTE: if this mass is type MassType.INFINITE or MassType.FIXED_LINEAR_VELOCITY this method returns zero.
    
    Returns:
    
    double
  - getInverseInertia
```
public double getInverseInertia()
```
    Returns the inverse inertia tensor.
    NOTE: if this mass is type MassType.INFINITE or MassType.FIXED_ANGULAR_VELOCITY this method returns zero.
    
    Returns:
    
    double

Class Mass

Constructor Summary

Method Summary

Methods inherited from class Object

Constructor Detail

Mass

Mass

Mass

Method Detail

copy

toString

hashCode

equals

create

isInfinite

setType

getType

getCenter

getMass

getInertia

getInverseMass

getInverseInertia