Package armyc2.c2sd.graphics2d

Class QuadCurve2D

java.lang.Object

armyc2.c2sd.graphics2d.QuadCurve2D

public final class QuadCurve2D
extends Object

The QuadCurve2D class defines a quadratic parametric curve segment in (x,y) coordinate space.

This class is only the abstract superclass for all objects that store a 2D quadratic curve segment. The actual storage representation of the coordinates is left to the subclass.

Since:

1.2

Constructor Summary

Constructors

Constructor	Description
QuadCurve2D()

Method Summary

Modifier and Type	Method	Description
Object	clone()
static double	getFlatnessSq(double[] coords, int offset)	Returns the square of the flatness, or maximum distance of a control point from the line connecting the end points, of the quadratic curve specified by the control points stored in the indicated array at the indicated index.
static double	getFlatnessSq2(double x1, double y1, double ctrlx, double ctrly, double x2, double y2)	Returns the square of the flatness, or maximum distance of a control point from the line connecting the end points, of the quadratic curve specified by the indicated control points.
static int	solveQuadratic(double[] eqn)	Solves the quadratic whose coefficients are in the eqn array and places the non-complex roots back into the same array, returning the number of roots.
static int	solveQuadratic2(double[] eqn, double[] res)	Solves the quadratic whose coefficients are in the eqn array and places the non-complex roots into the res array, returning the number of roots.
static void	subdivide(double[] src, int srcoff, double[] left, int leftoff, double[] right, int rightoff)	Subdivides the quadratic curve specified by the coordinates stored in the src array at indices srcoff through srcoff + 5 and stores the resulting two subdivided curves into the two result arrays at the corresponding indices.

Methods inherited from class java.lang.Object

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

Constructor Details

QuadCurve2D

public QuadCurve2D()

Method Details

getFlatnessSq2

public static double getFlatnessSq2(double x1,
 double y1,
 double ctrlx,
 double ctrly,
 double x2,
 double y2)

Returns the square of the flatness, or maximum distance of a control point from the line connecting the end points, of the quadratic curve specified by the indicated control points.

Parameters:

x1 - the X coordinate of the start point

y1 - the Y coordinate of the start point

ctrlx - the X coordinate of the control point

ctrly - the Y coordinate of the control point

x2 - the X coordinate of the end point

y2 - the Y coordinate of the end point

Returns:

the square of the flatness of the quadratic curve defined by the specified coordinates.

Since:

1.2

getFlatnessSq

public static double getFlatnessSq(double[] coords,
 int offset)

Returns the square of the flatness, or maximum distance of a control point from the line connecting the end points, of the quadratic curve specified by the control points stored in the indicated array at the indicated index.

Parameters:

coords - an array containing coordinate values

offset - the index into coords from which to to start getting the values from the array

Returns:

the flatness of the quadratic curve that is defined by the values in the specified array at the specified index.

Since:

1.2

subdivide

public static void subdivide(double[] src,
 int srcoff,
 double[] left,
 int leftoff,
 double[] right,
 int rightoff)

Subdivides the quadratic curve specified by the coordinates stored in the src array at indices srcoff through srcoff + 5 and stores the resulting two subdivided curves into the two result arrays at the corresponding indices. Either or both of the left and right arrays can be null or a reference to the same array and offset as the src array. Note that the last point in the first subdivided curve is the same as the first point in the second subdivided curve. Thus, it is possible to pass the same array for left and right and to use offsets such that rightoff equals leftoff + 4 in order to avoid allocating extra storage for this common point.

Parameters:

src - the array holding the coordinates for the source curve

srcoff - the offset into the array of the beginning of the the 6 source coordinates

left - the array for storing the coordinates for the first half of the subdivided curve

leftoff - the offset into the array of the beginning of the the 6 left coordinates

right - the array for storing the coordinates for the second half of the subdivided curve

rightoff - the offset into the array of the beginning of the the 6 right coordinates

Since:

1.2

solveQuadratic

public static int solveQuadratic(double[] eqn)

Solves the quadratic whose coefficients are in the eqn array and places the non-complex roots back into the same array, returning the number of roots. The quadratic solved is represented by the equation:

     eqn = {C, B, A};
     ax^2 + bx + c = 0
 

A return value of -1 is used to distinguish a constant equation, which might be always 0 or never 0, from an equation that has no zeroes.

Parameters:

eqn - the array that contains the quadratic coefficients

Returns:

the number of roots, or -1 if the equation is a constant

Since:

1.2

solveQuadratic2

public static int solveQuadratic2(double[] eqn,
 double[] res)

Solves the quadratic whose coefficients are in the eqn array and places the non-complex roots into the res array, returning the number of roots. The quadratic solved is represented by the equation:

     eqn = {C, B, A};
     ax^2 + bx + c = 0
 

A return value of -1 is used to distinguish a constant equation, which might be always 0 or never 0, from an equation that has no zeroes.

Parameters:

eqn - the specified array of coefficients to use to solve the quadratic equation

res - the array that contains the non-complex roots resulting from the solution of the quadratic equation

Returns:

the number of roots, or -1 if the equation is a constant.

Since:

1.3

clone

public Object clone()

Overrides:

clone in class Object