hmi.graphics.geometry
Class Polygon

java.lang.Object
  hmi.graphics.geometry.Polygon

public class Polygon
extends Object

A utility class for operations on polygons, like triangulation.

Field Summary

private int[]	index
private int[]	indices
private static Logger	logger
private float	nx
private float	ny
private float	nz
private int	vCount
private float[]	vertexCoords
private int	vertexOffset
private int	vertexStride

Constructor Summary

Polygon()
creates an empty/uninitialzed polgon object

Polygon(float[] vertexCoords, int vertexStride, int[] indices)

Method Summary

private void	calcNormal() calculates the normal vector for a polygon representing its surface area and orientation.
private void	delete(int pi) remove polgon vertex nr pi, within the rangle 0 .. vCount-1;
float	getArea()
private boolean	insideTriangle(int pi0, int pi1, int pi2, int q)
boolean	isEar(int pi) check whether the pi-1 mod vCount, pi, pi+1 mod vCount triangle forms an ear: left turn, and no other polgon point inside (or on the border of) the triangle.
private int	next(int p)
private int	prev(int p)
void	setVertexData(float[] vertexCoords, int vertexStride, int[] indices)
void	setVertices(int indexOffset, int vCount) assumes that setVertices has been called before,
private boolean	toLeft(int pi, int qi, int ri)
String	toString() Returns a String representation for debugging purposes
int	triangulate(int[] triangles, int triangleOffset) turn polygon into triangles.

Methods inherited from class java.lang.Object

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

Field Detail

vertexCoords

private float[] vertexCoords

indices

private int[] indices

vertexStride

private int vertexStride

vertexOffset

private int vertexOffset

index

private int[] index

vCount

private int vCount

nx

private float nx

ny

private float ny

nz

private float nz

logger

private static Logger logger

Constructor Detail

Polygon

public Polygon()

creates an empty/uninitialzed polgon object

Polygon

public Polygon(float[] vertexCoords,
               int vertexStride,
               int[] indices)

Method Detail

setVertexData

public void setVertexData(float[] vertexCoords,
                          int vertexStride,
                          int[] indices)

setVertices

public void setVertices(int indexOffset,
                        int vCount)

assumes that setVertices has been called before,

calcNormal

private void calcNormal()

calculates the normal vector for a polygon representing its surface area and orientation. The polygon vertices are allocated as floats within the vertices array; three consecutive floats represent one vertex. The offsets for the polygon vertices within the vertices array are provided within a set of indices, stored within the indices array. It is assumed that these indices are stored consecutively, starting at indexOffset, and that the number of vertices (therefore the number of indices) is specified by vCount.

getArea

public float getArea()

toLeft

private boolean toLeft(int pi,
                       int qi,
                       int ri)

insideTriangle

private boolean insideTriangle(int pi0,
                               int pi1,
                               int pi2,
                               int q)

isEar

public boolean isEar(int pi)

check whether the pi-1 mod vCount, pi, pi+1 mod vCount triangle forms an ear: left turn, and no other polgon point inside (or on the border of) the triangle.

prev

private int prev(int p)

next

private int next(int p)

delete

private void delete(int pi)

remove polgon vertex nr pi, within the rangle 0 .. vCount-1;

triangulate

public int triangulate(int[] triangles,
                       int triangleOffset)

turn polygon into triangles. The vertex coordinate data still resides in the vertexCoord datat array used by this polygon; This method requires an initialized int array, plus an offset into that array. The triangles will be added to this array, starting at the position denoted by offset, in the form of indices. The total number of triangles is returned.

toString

public String toString()

Returns a String representation for debugging purposes

Overrides:

toString in class Object