hmi.graphics.geometry
Class Triangulator

java.lang.Object
  hmi.graphics.geometry.Triangulator

public class Triangulator
extends Object

A utility class for operations on polygons, like triangulation.

Field Summary

private static Logger	logger
private float	nx
private float	ny
private float	nz
private int[]	polyIndex
private int	polyVCount
private float[]	vertexCoords
private int	vertexOffset
private int	vertexStride

Constructor Summary

Triangulator()
Creates a new Triangulator object, specifying vertex coordinates, vertex indices, and polygon vertex counts.

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;
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)
private boolean	toLeft(int pi, int qi, int ri)
String	toString() Returns a String representation for debugging purposes
int[]	triangulate(float[] vertexCoords, int vertexStride, int[] indices, int[] vCounts) triangulates the polygons of this Triangulator object, and returns the result in a new index array.
private int	triangulatePolygon(int[] triangles, int triangleOffset) turn a single 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

vertexStride

private int vertexStride

vertexOffset

private int vertexOffset

polyIndex

private int[] polyIndex

polyVCount

private int polyVCount

nx

private float nx

ny

private float ny

nz

private float nz

logger

private static Logger logger

Constructor Detail

Triangulator

public Triangulator()

Creates a new Triangulator object, specifying vertex coordinates, vertex indices, and polygon vertex counts. Vertex coordinates are stored inside vertexCoords, by means of three consecutive floats. Indices refer to these vertices: index i refers to a vertex starting at position i * vertexStride. Each element of vCounts defines the size of a polygon. The indices of each of these polygons are assumed to be stored consecutively in the indices array.

Method Detail

triangulate

public int[] triangulate(float[] vertexCoords,
                         int vertexStride,
                         int[] indices,
                         int[] vCounts)

triangulates the polygons of this Triangulator object, and returns the result in a new index array.

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.

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;

triangulatePolygon

private int triangulatePolygon(int[] triangles,
                               int triangleOffset)

turn a single 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