Phaser.Hermite

new Hermite(p1x, p1y, p2x, p2y, v1x, v1y, v2x, v2y, accuracy)

A data representation of a Hermite Curve (seehttp://en.wikipedia.org/wiki/Cubic_Hermite_spline)

A Hermite curve has a start and end point and tangent vectors for both of them. The curve will always pass through the two control points and the shape of it is controlled by the length and direction of the tangent vectors. At the control points the curve will be facing exactly in the vector direction.

As these curves change speed (speed = distance between points separatedby an equal change in 't' value - see Hermite.getPoint) this class attempts to reduce the variation by pre-calculating the accuracy number of points on the curve. The straight-line distances to these points are stored in the private 'points' array, and this information is used by Hermite.findT() to convert a pixel distance along the curve into a 'time' value.

Higher accuracy values will result in more even movement, but require more memory for the points list. 5 works, but 10 seems to be an ideal value for the length of curves found in most games on a desktop screen. If you use very long curves (more than 400 pixels) you may need to increase this value further.

Parameters:

Name

Type

Argument

Default

Description

p1x

number

The x coordinate of the start of the curve.

p1y

number

The y coordinate of the start of the curve.

p2x

number

The x coordinate of the end of the curve.

p2y

number

The y coordinate of the end of the curve.

v1x

number

The x component of the tangent vector for the start of the curve.

v1y

number

The y component of the tangent vector for the start of the curve.

v2x

number

The x component of the tangent vector for the end of the curve.

v2y

number

The y component of the tangent vector for the end of the curve.

accuracy

number

<optional>

10

The amount of points to pre-calculate on the curve.

Source - geom/Hermite.js, line 39

Members

accuracy:number

The amount of points to pre-calculate on the curve.

Source - geom/Hermite.js, line 396

p1x:number

The x coordinate of the start of the curve. Setting this value will recalculate the curve.

Source - geom/Hermite.js, line 420

p1y:number

The y coordinate of the start of the curve. Setting this value will recalculate the curve.

Source - geom/Hermite.js, line 444

p2x:number

The x coordinate of the end of the curve. Setting this value will recalculate the curve.

Source - geom/Hermite.js, line 468

p2y:number

The y coordinate of the end of the curve. Setting this value will recalculate the curve.

Source - geom/Hermite.js, line 492

v1x:number

The x component of the tangent vector for the start of the curve. Setting this value will recalculate the curve.

Source - geom/Hermite.js, line 516

v1y:number

The y component of the tangent vector for the start of the curve. Setting this value will recalculate the curve.

Source - geom/Hermite.js, line 540

v2x:number

The x component of the tangent vector for the end of the curve. Setting this value will recalculate the curve.

Source - geom/Hermite.js, line 564

v2y:number

The y component of the tangent vector for the end of the curve. Setting this value will recalculate the curve.

Source - geom/Hermite.js, line 588

calculateEvenPoints()→ {number}

Calculate a number of points along the curve, based on Hermite.accuracy, and stores them in the private _points array.

Returns:

number-

The total length of the curve approximated as straight line distances between the points.

Source - geom/Hermite.js, line 146

findT(distance)→ {number}

Convert a distance along this curve into a time value which will be between 0 and 1.

For example if this curve has a length of 100 pixels then findT(50) would return 0.5.

Parameters:

Name

Type

Description

distance

integer

The distance into the curve in pixels. Should be a positive integer.

Returns:

number-

The time (t) value, a float between 0 and 1.

Source - geom/Hermite.js, line 173

getAngle(t)→

{number}

Calculate and return the angle, in radians, of the curves tangent based on time.

Parameters:

Name

Type

Argument

Default

Description

t

number

<optional>

0

The t (time) value at which to find the angle. Must be between 0 and 1.

Returns:

number-

The angle of the line at the specified t time value along the curve. The value is in radians.

Source - geom/Hermite.js, line 336

getAngleWithDistance(distance)→ {number}

Calculate and return the angle, in radians, of the curves tangent at the given pixel distance along the curves length.

Parameters:

Name

Type

Argument

Default

Description

distance

number

<optional>

0

The distance along the curve to get the angle from, in pixels.

Returns:

number-

The angle of the line at the specified distance along the curve. The value is in radians.

Source - geom/Hermite.js, line 354

getEntryTangent(point)→ {Phaser.Point}

Get the angle of the curves entry point.

Parameters:

Name

Type

Description

point

Phaser.Point | Object

The Phaser.Point object, or an Object with public x and y properties, in which the tangent vector values will be stored.

Returns:

Phaser.Point-

A Point object containing the tangent vector of this Hermite curve.

Source - geom/Hermite.js, line 376

getPoint(t,point)→ {Phaser.Point}

Get a point on the curve using the t (time) value, which must be between 0 and 1.

Parameters:

Name

Type

Argument

Default

Description

t

number

<optional>

0

The time value along the curve from which to extract a point. This is a value between 0 and 1, where 0 represents the start of the curve and 1 the end.

point

Phaser.Point | Object

<optional>

An optional Phaser.Point, or Object containing public x and y properties. If given the resulting values will be stored in the Objects x and y properties. If omitted a new Phaser.Point object is created.

Returns:

Phaser.Point-

An Object with the x, y coordinate of the curve at the specified t value set in its x and y properties.

Source - geom/Hermite.js, line 276

getPointWithDistance(distance, point)→

{Phaser.Point}

Get a point on the curve using the distance, in pixels, along the curve.

Parameters:

Name

Type

Argument

Default

Description

distance

integer

<optional>

0

The distance along the curve to get the point from, given in pixels.

point

Phaser.Point | Object

<optional>

An optional Phaser.Point, or Object containing public x and y properties. If given the resulting values will be stored in the Objects x and y properties. If omitted a new Phaser.Point object is created.

Returns:

Phaser.Point-

The point on the line at the specified 'distance' along the curve.

Source - geom/Hermite.js, line 309

getX(t)→

{number}

Get the X component of a point on the curve based on the t (time) value, which must be between 0 and 1.

Parameters:

Name

Type

Argument

Default

Description

t

number

<optional>

0

The time value along the curve from which to extract a point. This is a value between 0 and 1, where 0 represents the start of the curve and 1 the end.

Returns:

number-

The X component of a point on the curve based on the t (time) value.

Source - geom/Hermite.js, line 210

getY(t)→

{number}

Get the Y component of a point on the curve based on the t (time) value, which must be between 0 and 1.

Parameters:

Name

Type

Argument

Default

Description

t

number

<optional>

0

The time value along the curve from which to extract a point. This is a value between 0 and 1, where 0 represents the start of the curve and 1 the end.

Returns:

number-

The Y component of a point on the curve based on the t (time) value.

Source - geom/Hermite.js, line 243

recalculate()→ {Phaser.Hermite}

Performs the curve calculations.

This is called automatically if you change any of the curves public properties, such as Hermite.p1x or Hermite.v2y.

If you adjust any of the internal private values, then call this to update the points.

Returns:

Phaser.Hermite-

This object.

Source - geom/Hermite.js, line 123