net.cscott.sdr.calls
Class ExactRotation

java.lang.Object
  net.cscott.sdr.calls.Rotation
      net.cscott.sdr.calls.ExactRotation

All Implemented Interfaces:

Comparable<ExactRotation>

public class ExactRotation
extends Rotation
implements Comparable<ExactRotation>

Rotations are represented as fractions, where '0' is facing north (away from the caller), and '1/4' is facing east. Positive denotes clockwise rotation.

Field Summary

static ExactRotation	EAST Common absolute rotations.
static ExactRotation	FIVE_EIGHTHS Common rotations.
static ExactRotation	mONE_QUARTER Common rotations.
static ExactRotation	NORTH Common absolute rotations.
static ExactRotation	ONE Common rotations.
static ExactRotation	ONE_EIGHTH Common rotations.
static ExactRotation	ONE_HALF Common rotations.
static ExactRotation	ONE_QUARTER Common rotations.
static ExactRotation	SEVEN_EIGHTHS Common rotations.
static ExactRotation	SOUTH Common absolute rotations.
static ExactRotation	THREE_EIGHTHS Common rotations.
static ExactRotation	THREE_QUARTERS Common rotations.
static ExactRotation	WEST Common absolute rotations.
static ExactRotation	ZERO Common rotations.

Fields inherited from class net.cscott.sdr.calls.Rotation

amount, modulus

Constructor Summary

ExactRotation(Fraction amount)
Constructor from a Fraction object.

Method Summary

ExactRotation	add(Fraction f) Add the given amount to this rotation direction.
int	compareTo(ExactRotation r) Compare unnormalized rotation amounts.
static ExactRotation	fromAbsoluteString(String s) Converts a string (one of n/s/e/w, ne/nw/se/sw) to the appropriate rotation object.
static ExactRotation	fromRelativeString(String s) Returns a ExactRotation corresponding to one of the strings "right", "left", or "none".
static ExactRotation	fromXY(Fraction x, Fraction y) Convert an x/y displacement to a rotation, using our 'squared off' circle.
boolean	isExact() Return true iff this rotation is exact (that is, if the modulus is one).
Fraction	minSweep(ExactRotation er) Compute the minimum angle (in absolute value) between this heading and the given heading er.
ExactRotation	negate() Negate this rotation (mirror image).
ExactRotation	normalize() Normalize rotation to the range [0, 1).
String	repr() Return an executable representation of this Rotation.
ExactRotation	subtract(Fraction f) Subtract the given amount from this rotation direction.
String	toAbsoluteString() Returns a human-readable description of the rotation.
char	toDiagramChar() Convert rotation to an appropriate ascii-art representation.
String	toRelativeString() Returns a human-readable description of the rotation.
String	toString() Returns a human-readable description of the rotation.
Fraction	toX() Return the X offset of a one-unit step in the rotation direction.
Fraction	toY() Return the Y offset of a one-unit step in the rotation direction.

Methods inherited from class net.cscott.sdr.calls.Rotation

create, equals, hashCode, included, includes, union, union

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

mONE_QUARTER

public static final ExactRotation mONE_QUARTER

Common rotations.

ZERO

public static final ExactRotation ZERO

Common rotations.

ONE_EIGHTH

public static final ExactRotation ONE_EIGHTH

Common rotations.

ONE_QUARTER

public static final ExactRotation ONE_QUARTER

Common rotations.

THREE_EIGHTHS

public static final ExactRotation THREE_EIGHTHS

Common rotations.

ONE_HALF

public static final ExactRotation ONE_HALF

Common rotations.

FIVE_EIGHTHS

public static final ExactRotation FIVE_EIGHTHS

Common rotations.

THREE_QUARTERS

public static final ExactRotation THREE_QUARTERS

Common rotations.

SEVEN_EIGHTHS

public static final ExactRotation SEVEN_EIGHTHS

Common rotations.

ONE

public static final ExactRotation ONE

Common rotations.

NORTH

public static final ExactRotation NORTH

Common absolute rotations.

EAST

public static final ExactRotation EAST

Common absolute rotations.

SOUTH

public static final ExactRotation SOUTH

Common absolute rotations.

WEST

public static final ExactRotation WEST

Common absolute rotations.

Constructor Detail

ExactRotation

public ExactRotation(Fraction amount)

Constructor from a Fraction object.

Method Detail

isExact

public boolean isExact()

Description copied from class: Rotation

Return true iff this rotation is exact (that is, if the modulus is one).

Overrides:

isExact in class Rotation

add

public ExactRotation add(Fraction f)

Add the given amount to this rotation direction.

Overrides:

add in class Rotation

subtract

public ExactRotation subtract(Fraction f)

Subtract the given amount from this rotation direction.

Overrides:

subtract in class Rotation

negate

public ExactRotation negate()

Negate this rotation (mirror image).

Overrides:

negate in class Rotation

normalize

public ExactRotation normalize()

Normalize rotation to the range [0, 1).

Overrides:

normalize in class Rotation

compareTo

public int compareTo(ExactRotation r)

Compare unnormalized rotation amounts.

Specified by:

compareTo in interface Comparable<ExactRotation>

minSweep

public Fraction minSweep(ExactRotation er)

Compute the minimum angle (in absolute value) between this heading and the given heading er. The result is positive or negative, and can be added to this heading to yield a rotation equivalent to the given heading er.

Tests:

js> ExactRotation.ONE_EIGHTH.minSweep(ExactRotation.SEVEN_EIGHTHS);
-1/4
js> ExactRotation.SEVEN_EIGHTHS.minSweep(ExactRotation.ONE_EIGHTH);
1/4

toAbsoluteString

public String toAbsoluteString()

Returns a human-readable description of the rotation. The output is a valid input to ExactRotation.fromAbsoluteString(String).

Overrides:

toAbsoluteString in class Rotation

toRelativeString

public String toRelativeString()

Returns a human-readable description of the rotation. The output is a valid input to ExactRotation.fromAbsoluteString(String).

fromAbsoluteString

public static ExactRotation fromAbsoluteString(String s)

Converts a string (one of n/s/e/w, ne/nw/se/sw) to the appropriate rotation object. 'n' is facing away from the caller.

repr

public String repr()

Description copied from class: Rotation

Return an executable representation of this Rotation.

Overrides:

repr in class Rotation

fromRelativeString

public static ExactRotation fromRelativeString(String s)

Returns a ExactRotation corresponding to one of the strings "right", "left", or "none".

Parameters:

s -

Returns:

ExactRotation.ZERO if s is "none", ExactRotation.ONE_QUARTER if s is "right", or ExactRotation.mONE_QUARTER if s is "left".

Throws:

IllegalArgumentException - if s is not one of "right", "left", "none", or a number.

toX

public Fraction toX()

Return the X offset of a one-unit step in the rotation direction. Zero indicates north (towards positive y). Use a 'squared off' circle to avoid irrational numbers. This is roughly equivalent to sin(amount).

See Also:

toY()

Tests:

js> importPackage(net.cscott.sdr.util);
js> for (n=-8; n<20; n++) {
  >  er = new ExactRotation(Fraction.valueOf(n, 16));
  >  print("toX("+er+")="+er.toX().toProperString());
  > }; undefined
toX(-1/2)=0
toX(-7/16)=-1/2
toX(-3/8)=-1
toX(-5/16)=-1
toX(-1/4)=-1
toX(-3/16)=-1
toX(-1/8)=-1
toX(-1/16)=-1/2
toX(0)=0
toX(1/16)=1/2
toX(1/8)=1
toX(3/16)=1
toX(1/4)=1
toX(5/16)=1
toX(3/8)=1
toX(7/16)=1/2
toX(1/2)=0
toX(9/16)=-1/2
toX(5/8)=-1
toX(11/16)=-1
toX(3/4)=-1
toX(13/16)=-1
toX(7/8)=-1
toX(15/16)=-1/2
toX(1)=0
toX(1 1/16)=1/2
toX(1 1/8)=1
toX(1 3/16)=1

toY

public Fraction toY()

Return the Y offset of a one-unit step in the rotation direction. Zero indicates north (towards positive y). Use a 'squared off' circle to avoid irrational numbers. This is roughly equivalent to cos(amt).

See Also:

toX()

Tests:

js> importPackage(net.cscott.sdr.util);
js> for (n=-8; n<20; n++) {
  >  er = new ExactRotation(Fraction.valueOf(n, 16));
  >  print("toY("+er+")="+er.toY().toProperString());
  > }; undefined
toY(-1/2)=-1
toY(-7/16)=-1
toY(-3/8)=-1
toY(-5/16)=-1/2
toY(-1/4)=0
toY(-3/16)=1/2
toY(-1/8)=1
toY(-1/16)=1
toY(0)=1
toY(1/16)=1
toY(1/8)=1
toY(3/16)=1/2
toY(1/4)=0
toY(5/16)=-1/2
toY(3/8)=-1
toY(7/16)=-1
toY(1/2)=-1
toY(9/16)=-1
toY(5/8)=-1
toY(11/16)=-1/2
toY(3/4)=0
toY(13/16)=1/2
toY(7/8)=1
toY(15/16)=1
toY(1)=1
toY(1 1/16)=1
toY(1 1/8)=1
toY(1 3/16)=1/2

fromXY

public static ExactRotation fromXY(Fraction x,
                                   Fraction y)

Convert an x/y displacement to a rotation, using our 'squared off' circle. Roughly equivalent to atan2().

toString

public String toString()

Description copied from class: Rotation

Returns a human-readable description of the rotation. The output is a valid input to ExactRotation.valueOf(String).

Overrides:

toString in class Rotation

toDiagramChar

public char toDiagramChar()

Convert rotation to an appropriate ascii-art representation. The character '.' is used for "unrepresentable rotations". The southeast and northwest characters are a little funny.

Overrides:

toDiagramChar in class Rotation

Tests:

Show rotations going CW from north:

js> function c2s(c) { return String.fromCharCode(c) }
js> [c2s(r.toDiagramChar()) for each (r in 
  >  [ExactRotation.NORTH, ExactRotation.EAST,
  >   ExactRotation.SOUTH, ExactRotation.WEST])]
^,>,v,<
js> [c2s(r.toDiagramChar()) for each (r in 
  >  [ExactRotation.ONE_EIGHTH, ExactRotation.THREE_EIGHTHS,
  >   ExactRotation.FIVE_EIGHTHS, ExactRotation.SEVEN_EIGHTHS])]
7,Q,L,`
js> c2s(new ExactRotation(net.cscott.sdr.util.Fraction.valueOf(1,3))
  >     .toDiagramChar())
.