org.oscim.utils.geom

Class GeometryUtils

java.lang.Object

org.oscim.utils.geom.GeometryUtils

public final class GeometryUtils
extends java.lang.Object

Method Summary

Modifier and Type	Method and Description
static float	area(float[] points, int size) Returns the unsigned area of polygon.
static float	area(float[] a, int p1, int p2, int p3)
static float	area(float ax, float ay, float bx, float by, float cx, float cy)
static float[]	bisectionNorm2D(float[] v1, float[] v2)
static float[]	center(float[] points, int pointPos, int n, float[] out) Calculates the center of a set of points.
static float[]	diffVec(float[] a, float[] b)
static double	distance(float[] p, int a, int b)
static double	distance2D(float[] a, float[] b)
static float	distancePointLine2D(float[] pP, float[] pL, float[] vL)
static float	dotProduct(float[] a, float[] b)
static double	dotProduct(float[] p, int a, int b, int c)
static float[]	intersectionLinePlane(float[] pL, float[] vL, float[] pP, float[] vP) Calculate intersection of a plane with a line
static float[]	intersectionLines2D(float[] pA, float[] vA, float[] pB, float[] vB)
static float	isClockwise(float[] points, int size) Is polygon clockwise.
static float	isTrisClockwise(float[] pA, float[] pB, float[] pC) Indicates the turn of tris pA-pB-pC.
static double	length(float[] vec)
static float[]	normalize(float[] vec)
static java.util.List<float[]>	normalizedVectors2D(java.util.List<float[]> points, java.util.List<java.lang.Float> outLengths) Calculate the normalized direction vectors of point list (polygon)
static float[]	normalOfPlane(float[] pA, float[] pB, float[] pC)
static boolean	pointInPoly(float x, float y, float[] vertices, int length, int offset) Test if point x/y is in polygon defined by vertices[offset ...
static float[]	scale(float[] v, float scale)
static float	squaredDistance(float[] p, int a, int b)
static float	squareSegmentDistance(float[] p, int a, int b, int c) square distance from a point a to a segment b,c
static float[]	sumVec(float[] a, float[] b)

Methods inherited from class java.lang.Object

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

Method Detail

pointInPoly

public static boolean pointInPoly(float x,
                                  float y,
                                  float[] vertices,
                                  int length,
                                  int offset)

Test if point x/y is in polygon defined by vertices[offset ... offset+length]

-- from www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html

If there is only one connected component, then it is optional to repeat the first vertex at the end. It's also optional to surround the component with zero vertices.

The polygon may contain multiple separate components, and/or holes, provided that you separate the components and holes with a (0,0) vertex, as follows.

First, include a (0,0) vertex. Then include the first component' vertices, repeating its first vertex after the last vertex. Include another (0,0) vertex. Include another component or hole, repeating its first vertex after the last vertex. Repeat the above two steps for each component and hole. Include a final (0,0) vertex.

Each component or hole's vertices may be listed either clockwise or counter-clockwise.

area

public static float area(float[] points,
                         int size)

Returns the unsigned area of polygon.

Parameters:

size - the number of point coordinates

Returns:

unsigned polygon area

area

public static float area(float ax,
                         float ay,
                         float bx,
                         float by,
                         float cx,
                         float cy)

area

public static float area(float[] a,
                         int p1,
                         int p2,
                         int p3)

bisectionNorm2D

public static float[] bisectionNorm2D(float[] v1,
                                      float[] v2)

Parameters:

v1 - the first normalized vector

v2 - the second normalized vector

Returns:

the bisection of the to vectors

center

public static float[] center(float[] points,
                             int pointPos,
                             int n,
                             float[] out)

Calculates the center of a set of points.

Parameters:

points - the points array

pointPos - the start position of points

n - the number of points

out - the center output

Returns:

the center of points

diffVec

public static float[] diffVec(float[] a,
                              float[] b)

Parameters:

a - first vector

b - second vector

Returns:

a - b

sumVec

public static float[] sumVec(float[] a,
                             float[] b)

Parameters:

a - first vector

b - second vector

Returns:

a + b

squaredDistance

public static float squaredDistance(float[] p,
                                    int a,
                                    int b)

squareSegmentDistance

public static float squareSegmentDistance(float[] p,
                                          int a,
                                          int b,
                                          int c)

square distance from a point a to a segment b,c

distance

public static double distance(float[] p,
                              int a,
                              int b)

distance2D

public static double distance2D(float[] a,
                                float[] b)

Parameters:

a - point a[x,y]

b - point b[x,y]

Returns:

the distance between a and b.

distancePointLine2D

public static float distancePointLine2D(float[] pP,
                                        float[] pL,
                                        float[] vL)

Parameters:

pP - point

pL - point of line

vL - vector of line

Returns:

the minimum distance between line and point

dotProduct

public static double dotProduct(float[] p,
                                int a,
                                int b,
                                int c)

dotProduct

public static float dotProduct(float[] a,
                               float[] b)

Parameters:

a - first vector

b - second vector

Returns:

the dot product

intersectionLines2D

public static float[] intersectionLines2D(float[] pA,
                                          float[] vA,
                                          float[] pB,
                                          float[] vB)

Parameters:

pA - position vector of A

vA - direction vector of A

pB - position vector of B

vB - direction vector of B

Returns:

the intersection point

intersectionLinePlane

public static float[] intersectionLinePlane(float[] pL,
                                            float[] vL,
                                            float[] pP,
                                            float[] vP)

Calculate intersection of a plane with a line

Parameters:

pL - position vector of line

vL - direction vector of line

pP - position vector of plane

vP - normal vector of plane

Returns:

the intersection point

isClockwise

public static float isClockwise(float[] points,
                                int size)

Is polygon clockwise. Note that the coordinate system is left hand side.

Parameters:

points - the points array

size - the number of point coordinates

Returns:

the signed area of the polygon positive: clockwise negative: counter-clockwise 0: collinear

isTrisClockwise

public static float isTrisClockwise(float[] pA,
                                    float[] pB,
                                    float[] pC)

Indicates the turn of tris pA-pB-pC. Note that the coordinate system is left hand side.

Returns:

positive: clockwise negative: counter-clockwise 0: collinear

length

public static double length(float[] vec)

Returns:

the length of the vector

normalize

public static float[] normalize(float[] vec)

Returns:

the normalized vector (with length 1)

normalizedVectors2D

public static java.util.List<float[]> normalizedVectors2D(java.util.List<float[]> points,
                                                          java.util.List<java.lang.Float> outLengths)

Calculate the normalized direction vectors of point list (polygon)

Parameters:

points - the list of 2D points

outLengths - the optional list to store lengths of vectors

Returns:

the normalized direction vectors

normalOfPlane

public static float[] normalOfPlane(float[] pA,
                                    float[] pB,
                                    float[] pC)

Parameters:

pA - first point of plane

pB - second point of plane

pC - third point of plane

Returns:

the normal of plane

scale

public static float[] scale(float[] v,
                            float scale)

Parameters:

v - the vector

scale - the scale

Returns:

the scaled vector