Rac. Angle

Angle measured by a turn value in the range [0,1) that represents the amount of turn in a full circle.

Most functions through RAC that can receive an Angle parameter can also receive a number value that will be used as turn to instantiate a new Angle. The main exception to this behaviour are constructors, which always expect to receive Angle objects.

For drawing operations the turn value is interpreted to be pointing to the following directions:

  • 0/4 - points right
  • 1/4 - points downwards
  • 2/4 - points left
  • 3/4 - points upwards

Constructor

new Angle(rac, turn)

# | source: drawable/Angle.js, line 26

Creates a new Angle instance.

The turn value is constrained to the rance [0, 1), any value outside is reduced back into range using a modulo operation.

new Rac.Angle(rac, 1/4)  // turn is 1/4
new Rac.Angle(rac, 5/4)  // turn is 1/4
new Rac.Angle(rac, -1/4) // turn is 3/4
new Rac.Angle(rac, 1)    // turn is 0
new Rac.Angle(rac, 4)    // turn is 0
Parameters:
Name Type Description
rac Rac

Instance to use for drawing and creating other objects
turn number

The turn value

Members

rac :Rac

# | source: drawable/Angle.js, line 54

Intance of Rac used for drawing and passed along to any created object.

turn :number

# | source: drawable/Angle.js, line 65

Turn value of the angle, constrained to the range [0, 1).

Methods

(static) from(rac, something) → {Rac.Angle}

# | source: drawable/Angle.js, line 126

Returns an Angle derived from something.

  • When something is an instance of Angle, returns that same object.
  • When something is a number, returns a new Angle with something as turn.
  • When something is a Rac.Ray, returns its angle.
  • When something is a Rac.Segment, returns its angle.
  • Otherwise an error is thrown.
Parameters:
Name Type Description
rac Rac

Instance to pass along to newly created objects
something Rac.Angle | Rac.Ray | Rac.Segment | number

An object to derive an Angle from

(static) fromRadians(rac, radians) → {Rac.Angle}

# | source: drawable/Angle.js, line 151

Returns an Angle derived from radians.

Parameters:
Name Type Description
rac Rac

Instance to pass along to newly created objects
radians number

The measure of the angle, in radians

add(angle) → {Rac.Angle}

# | source: drawable/Angle.js, line 231

Returns a new Angle with the sum of this and the angle derived from angle.

Parameters:
Name Type Description
angle Rac.Angle | number

An Angle to add

degrees() → {number}

# | source: drawable/Angle.js, line 211

Returns the measure of the angle in degrees.

distance(angle, clockwiseopt) → {Rac.Angle}

# | source: drawable/Angle.js, line 287

Returns a new Angle that represents the distance from this to the angle derived from angle.

rac.Angle(1/4).distance(1/2, true)  // turn is 1/2
rac.Angle(1/4).distance(1/2, false) // turn in 3/4
Parameters:
Name Type Attributes Default Description
angle Rac.Angle | number

An Angle to measure the distance to
clockwise boolean <optional>
 true

The orientation of the measurement

equals(angle) → {boolean}

# | source: drawable/Angle.js, line 95

Returns true when the difference with the turn value of the angle derived from angle is under Rac#unitaryEqualityThreshold, otherwise returns false.

For this method otherAngle can only be Angle or number, any other type returns false.

This method will consider turn values in the oposite ends of the range [0, 1) as equals. E.g. Angle objects with turn values of 0 and 1 - rac.unitaryEqualityThreshold/2 will be considered equal.

Parameters:
Name Type Description
angle Rac.Angle | number

An Angle to compare

inverse() → {Rac.Angle}

# | source: drawable/Angle.js, line 168

Returns a new Angle pointing in the opposite direction to this.

rac.Angle(1/8).inverse() // turn is 1/8 + 1/2 = 5/8
rac.Angle(7/8).inverse() // turn is 7/8 + 1/2 = 3/8

mult(factor) → {Rac.Angle}

# | source: drawable/Angle.js, line 252

Returns a new Angle with turn`` set to this.turn * factor`.

Parameters:
Name Type Description
factor number

The factor to multiply turn by

multOne(factor) → {number}

# | source: drawable/Angle.js, line 271

Returns a new Angle with turn set to this.turnOne() * factor.

Useful when doing ratio calculations where a zero angle corresponds to a complete-circle since:

rac.Angle(0).mult(0.5)    // turn is 0
// whereas
rac.Angle(0).multOne(0.5) // turn is 0.5
Parameters:
Name Type Description
factor number

The factor to multiply turn by

negative() → {Rac.Angle}

# | source: drawable/Angle.js, line 181

Returns a new Angle with a turn value equivalent to -turn.

rac.Angle(1/4).negative() // -1/4 becomes turn 3/4
rac.Angle(3/8).negative() // -3/8 becomes turn 5/8

perpendicular() → {Rac.Angle}

# | source: drawable/Angle.js, line 195

Returns a new Angle which is perpendicular to this in the clockwise orientation.

rac.Angle(1/8).perpendicular(true)  // turn is 1/8 + 1/4 = 3/8
rac.Angle(1/8).perpendicular(false) // turn is 1/8 - 1/4 = 7/8

radians() → {number}

# | source: drawable/Angle.js, line 203

Returns the measure of the angle in radians.

shift(angle, clockwiseopt) → {Rac.Angle}

# | source: drawable/Angle.js, line 312

Returns a new Angle result of shifting the angle derived from angle to have this as its origin.

This operation is the equivalent to

  • this.add(angle) when clockwise
  • this.subtract(angle) when counter-clockwise
rac.Angle(0.1).shift(0.3, true)  // turn is 0.1 + 0.3 = 0.4
rac.Angle(0.1).shift(0.3, false) // turn is 0.1 - 0.3 = 0.8
Parameters:
Name Type Attributes Default Description
angle Rac.Angle | number

An Angle to be shifted
clockwise boolean <optional>
 true

The orientation of the shift

shiftToOrigin(origin, clockwiseopt) → {Rac.Angle}

# | source: drawable/Angle.js, line 337

Returns a new Angle result of shifting this to have the angle derived from origin as its origin.

This operation is the equivalent to

  • origin.add(this) when clockwise
  • origin.subtract(this) when counter-clockwise
rac.Angle(0.1).shiftToOrigin(0.3, true)  // turn is 0.3 + 0.1 = 0.4
rac.Angle(0.1).shiftToOrigin(0.3, false) // turn is 0.3 - 0.1 = 0.2
Parameters:
Name Type Attributes Default Description
origin Rac.Angle | number

An Angle to use as origin
clockwise boolean <optional>
 true

The orientation of the shift

subtract(angle) → {Rac.Angle}

# | source: drawable/Angle.js, line 242

Returns a new Angle with the angle derived from angle subtracted to this.

Parameters:
Name Type Description
angle Rac.Angle | number

An Angle to subtract

toString(digitsopt) → {string}

# | source: drawable/Angle.js, line 75

Returns a string representation intended for human consumption.

Parameters:
Name Type Attributes Default Description
digits number <optional>
 null

The number of digits to print after the decimal point, when ommited all digits are printed

turnOne() → {number}

# | source: drawable/Angle.js, line 220

Returns the turn value in the range (0, 1]. When turn is equal to 0 returns 1 instead.