org.jmol.util

Class MeshCapper

java.lang.Object

org.jmol.util.MeshCapper

public class MeshCapper
extends java.lang.Object

A class to properly cap a convoluted, closed slice of an isosurface inspired by: Computational Geometry: Algorithms and Applications Mark de Berg, Marc van Kreveld, Mark Overmars, and Otfried Schwarzkopf Springer-Verlag, Berlin Heidelberg 1997 Chapter 3. Polygon Triangulation Thanks given to Olaf Hall-Holt for pointing me to this reference. Extensively modified: - quaternion transform from 3D plane to XY plane for best precision - using directional edges -- no angle measurements necessary - continuous splitting off of triangles - independent dynamic monotonic regions created and processed as one stream - no need for vertex typing - no push/pop stacks INPUT: stream of [a b] ordered-vertex edges such that triangle a-b-c is interior if (ab.cross.ac).dot.planeNormal > 0 (right-hand rule; counter-clockwise edge flow) Bob Hanson - Jan 11, 2015

Author:

Bob Hanson, hansonr@stolaf.edu

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private class	MeshCapper.CapVertex A class to provide linked vertices for MeshCapper

Field Summary

Fields

Modifier and Type	Field and Description
private static int	ASCENDER
private java.util.Map<java.lang.Integer,MeshCapper.CapVertex>	capMap initialization only
private static int	DESCENDER
private boolean	dumping for debugging
private static int	LAST
private javajs.util.Lst<MeshCapper.CapVertex[]>	lstRegions dynamic region processing.
private int	nRegions informational only
private int	nTriangles informational only
private MeshSlicer	slicer source of edges; consumer of triangles
private boolean	testing for debugging
private javajs.util.Lst<MeshCapper.CapVertex>	vertices

Constructor Summary

Constructors

Constructor and Description
MeshCapper()

Method Summary

Modifier and Type	Method and Description
(package private) void	addEdge(int ipt1, int ipt2, int thisSet) Input method from MeshSlicer.
private MeshCapper.CapVertex	addPoint(int thisSet, int i) The MeshSlicer class manages all introduction of vertices; we must pass on to it the subset of vertices from the original Jmol isosurface being capped.
private void	addTriangle(MeshCapper.CapVertex v0, MeshCapper.CapVertex v1, MeshCapper.CapVertex v2, java.lang.String note) Add the triangle and remove v1 from the chain.
private boolean	checkWinding(MeshCapper.CapVertex v0, MeshCapper.CapVertex v1, MeshCapper.CapVertex v2) Check for CCW winding.
(package private) void	clear()
(package private) void	createCap(javajs.util.V3 norm) Entry point when finished generating edges.
private void	drawTriangle(int index, MeshCapper.CapVertex v0, MeshCapper.CapVertex v1, MeshCapper.CapVertex v2, java.lang.String color) for debugging
private javajs.util.T3	getInputPoint(MeshCapper.CapVertex v) for debugging
private MeshCapper.CapVertex	getLastPoint(MeshCapper.CapVertex v) Find the lowest ascender or descender above scan line bounding the region for this point.
private void	newRegion(MeshCapper.CapVertex v) Add a new region to the list of regions.
private void	outputTriangle(int ipt1, int ipt2, int ipt3) Export triangle to MeshSlicer
private MeshCapper.CapVertex	process(MeshCapper.CapVertex v) Handle the point; mark as processed.
private void	processMonotonic(MeshCapper.CapVertex v, boolean isDescending) Process a standard monotonic region, cleaving off as many triangles as possible.
private MeshCapper.CapVertex	processSplit(MeshCapper.CapVertex v, MeshCapper.CapVertex last) Process what M3O refer to as a "split" vertex, which we handle differently here, cloning the "helper" point and the "split" point, creating a new region if necessary, and then swapping pointers.
(package private) MeshCapper	set(MeshSlicer slicer)
private MeshCapper.CapVertex[]	test(MeshCapper.CapVertex[] vs)

Methods inherited from class java.lang.Object

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

Field Detail

slicer

private MeshSlicer slicer

source of edges; consumer of triangles

dumping

private boolean dumping

for debugging

testing

private boolean testing

for debugging

capMap

private java.util.Map<java.lang.Integer,MeshCapper.CapVertex> capMap

initialization only

vertices

private javajs.util.Lst<MeshCapper.CapVertex> vertices

lstRegions

private javajs.util.Lst<MeshCapper.CapVertex[]> lstRegions

dynamic region processing. These are just [DESCENDER, ASCENDER, LAST] for each region

DESCENDER

private static final int DESCENDER

See Also:

Constant Field Values

ASCENDER

private static final int ASCENDER

See Also:

Constant Field Values

LAST

private static final int LAST

See Also:

Constant Field Values

nTriangles

private int nTriangles

informational only

nRegions

private int nRegions

informational only

Constructor Detail

MeshCapper

public MeshCapper()

Method Detail

set

MeshCapper set(MeshSlicer slicer)

Parameters:

slicer -

Returns:

this

clear

void clear()

addEdge

void addEdge(int ipt1,
             int ipt2,
             int thisSet)

Input method from MeshSlicer. Pointers are into MeshSlicer.m.vs[]

Parameters:

ipt1 -

ipt2 -

thisSet -

addPoint

private MeshCapper.CapVertex addPoint(int thisSet,
                                      int i)

The MeshSlicer class manages all introduction of vertices; we must pass on to it the subset of vertices from the original Jmol isosurface being capped.

Parameters:

thisSet -

i -

Returns:

a CapVertex pointing to this new point in the isosurface or one we already have

getInputPoint

private javajs.util.T3 getInputPoint(MeshCapper.CapVertex v)

for debugging

Parameters:

v -

Returns:

external point or test point

outputTriangle

private void outputTriangle(int ipt1,
                            int ipt2,
                            int ipt3)

Export triangle to MeshSlicer

Parameters:

ipt1 -

ipt2 -

ipt3 -

test

private MeshCapper.CapVertex[] test(MeshCapper.CapVertex[] vs)

createCap

void createCap(javajs.util.V3 norm)

Entry point when finished generating edges.

Parameters:

norm -

process

private MeshCapper.CapVertex process(MeshCapper.CapVertex v)

Handle the point; mark as processed.

Parameters:

v -

Returns:

next point to process

processMonotonic

private void processMonotonic(MeshCapper.CapVertex v,
                              boolean isDescending)

Process a standard monotonic region, cleaving off as many triangles as possible.

Parameters:

v -

isDescending -

processSplit

private MeshCapper.CapVertex processSplit(MeshCapper.CapVertex v,
                                          MeshCapper.CapVertex last)

Process what M3O refer to as a "split" vertex, which we handle differently here, cloning the "helper" point and the "split" point, creating a new region if necessary, and then swapping pointers.

Parameters:

v -

last - "helper" or left edge

Returns:

new point clone of this

newRegion

private void newRegion(MeshCapper.CapVertex v)

Add a new region to the list of regions.

Parameters:

v -

getLastPoint

private MeshCapper.CapVertex getLastPoint(MeshCapper.CapVertex v)

Find the lowest ascender or descender above scan line bounding the region for this point. In the case of a region that consists of a single edge with descender above ascender, this will return the ascender. In the case where there are two independent regions, it is possible for the lowest to be missed, but to no import. [This is MOST confusing in the M3O book.]

Parameters:

v -

Returns:

pt

checkWinding

private boolean checkWinding(MeshCapper.CapVertex v0,
                             MeshCapper.CapVertex v1,
                             MeshCapper.CapVertex v2)

Check for CCW winding.

Parameters:

v0 -

v1 -

v2 -

Returns:

true if properly wound -- (v1-v0).cross.(v2-v0).dot.norm > 0

addTriangle

private void addTriangle(MeshCapper.CapVertex v0,
                         MeshCapper.CapVertex v1,
                         MeshCapper.CapVertex v2,
                         java.lang.String note)

Add the triangle and remove v1 from the chain.

Parameters:

v0 -

v1 -

v2 -

note -

drawTriangle

private void drawTriangle(int index,
                          MeshCapper.CapVertex v0,
                          MeshCapper.CapVertex v1,
                          MeshCapper.CapVertex v2,
                          java.lang.String color)

for debugging

Parameters:

index -

v0 -

v1 -

v2 -

color -