364 lines
13 KiB
C#
364 lines
13 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Text;
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using OpenSim.Framework.Console;
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namespace OpenSim.Region.Physics.Meshing
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{
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// A simple hull is a set of vertices building up to simplices that border a region
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// The word simple referes to the fact, that this class assumes, that all simplices
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// do not intersect
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// Simple hulls can be added and subtracted.
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// Vertices can be checked to lie inside a hull
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// Also note, that the sequence of the vertices is important and defines if the region that
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// is defined by the hull lies inside or outside the simplex chain
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public class SimpleHull
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{
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List<Vertex> vertices = new List<Vertex>();
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List<Vertex> holeVertices = new List<Vertex>(); // Only used, when the hull is hollow
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// Adds a vertex to the end of the list
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public void AddVertex(Vertex v) {
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vertices.Add(v);
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}
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override public String ToString()
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{
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String result="";
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foreach (Vertex v in vertices)
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{
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result += "b:" + v.ToString() + "\n";
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}
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return result;
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}
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public List<Vertex> getVertices() {
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List<Vertex> newVertices = new List<Vertex>();
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newVertices.AddRange(vertices);
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newVertices.Add(null);
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newVertices.AddRange(holeVertices);
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return newVertices;
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}
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public SimpleHull Clone()
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{
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SimpleHull result = new SimpleHull();
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foreach (Vertex v in vertices)
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{
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result.AddVertex(v.Clone());
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}
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foreach (Vertex v in this.holeVertices)
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{
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result.holeVertices.Add(v.Clone());
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}
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return result;
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}
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public bool IsPointIn(Vertex v1)
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{
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int iCounter=0;
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List<Simplex> simplices=buildSimplexList();
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foreach (Simplex s in simplices)
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{
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// Send a ray along the positive X-Direction
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// Note, that this direction must correlate with the "below" interpretation
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// of handling for the special cases below
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Manager.PhysicsVector intersection = s.RayIntersect(v1, new Manager.PhysicsVector(1.0f, 0.0f, 0.0f), true);
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if (intersection == null)
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continue; // No intersection. Done. More tests to follow otherwise
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// Did we hit the end of a simplex?
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// Then this can be one of two special cases:
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// 1. we go through a border exactly at a joint
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// 2. we have just marginally touched a corner
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// 3. we can slide along a border
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// Solution: If the other vertex is "below" the ray, we don't count it
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// Thus corners pointing down are counted twice, corners pointing up are not counted
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// borders are counted once
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if (intersection.IsIdentical(s.v1, 0.001f)) {
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if (s.v2.Y < v1.Y)
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continue;
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}
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// Do this for the other vertex two
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if (intersection.IsIdentical(s.v2, 0.001f)) {
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if (s.v1.Y<v1.Y)
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continue;
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}
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iCounter++;
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}
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return iCounter % 2 == 1; // Point is inside if the number of intersections is odd
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}
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public bool containsPointsFrom(SimpleHull otherHull)
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{
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foreach (Vertex v in otherHull.vertices)
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{
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if (IsPointIn(v))
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return true;
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}
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return false;
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}
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List<Simplex> buildSimplexList() {
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List<Simplex> result = new List<Simplex>();
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// Not asserted but assumed: at least three vertices
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for (int i=0; i<vertices.Count-1; i++) {
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Simplex s=new Simplex(vertices[i], vertices[i+1]);
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result.Add(s);
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}
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Simplex s1=new Simplex(vertices[vertices.Count-1], vertices[0]);
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result.Add(s1);
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if (holeVertices.Count==0)
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return result;
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// Same here. At least three vertices in hole assumed
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for (int i = 0; i < holeVertices.Count - 1; i++)
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{
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Simplex s = new Simplex(holeVertices[i], holeVertices[i + 1]);
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result.Add(s);
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}
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s1 = new Simplex(holeVertices[holeVertices.Count - 1], holeVertices[0]);
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result.Add(s1);
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return result;
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}
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bool InsertVertex(Vertex v, int iAfter)
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{
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vertices.Insert(iAfter + 1, v);
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return true;
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}
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Vertex getNextVertex(Vertex currentVertex)
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{
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int iCurrentIndex;
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iCurrentIndex = vertices.IndexOf(currentVertex);
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// Error handling for iCurrentIndex==-1 should go here (and probably never will)
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iCurrentIndex++;
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if (iCurrentIndex == vertices.Count)
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iCurrentIndex = 0;
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return vertices[iCurrentIndex];
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}
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public Vertex FindVertex(Vertex vBase, float tolerance) {
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foreach (Vertex v in vertices) {
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if (v.IsIdentical(vBase, tolerance))
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return v;
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}
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return null;
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}
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public void FindIntersection(Simplex s, ref Vertex Intersection, ref Vertex nextVertex)
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{
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Vertex bestIntersection=null;
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float distToV1=Single.PositiveInfinity;
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Simplex bestIntersectingSimplex=null;
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List<Simplex> simple = buildSimplexList();
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foreach (Simplex sTest in simple)
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{
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Manager.PhysicsVector vvTemp = Simplex.Intersect(sTest, s, -.001f, -.001f, 0.999f, .999f);
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Vertex vTemp=null;
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if (vvTemp != null)
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vTemp = new Vertex(vvTemp);
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if (vTemp!=null) {
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Manager.PhysicsVector diff=(s.v1-vTemp);
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float distTemp=diff.length();
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if (bestIntersection==null || distTemp<distToV1) {
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bestIntersection=vTemp;
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distToV1=distTemp;
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bestIntersectingSimplex = sTest;
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}
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} // end if vTemp
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} // end foreach
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Intersection = bestIntersection;
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if (bestIntersectingSimplex != null)
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nextVertex = bestIntersectingSimplex.v2;
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else
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nextVertex = null;
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}
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public static SimpleHull SubtractHull(SimpleHull baseHull, SimpleHull otherHull)
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{
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SimpleHull baseHullClone = baseHull.Clone();
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SimpleHull otherHullClone = otherHull.Clone();
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bool intersects = false;
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MainLog.Instance.Debug("State before intersection detection");
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MainLog.Instance.Debug("The baseHull is:\n{1}", 0, baseHullClone.ToString());
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MainLog.Instance.Debug("The otherHull is:\n{1}", 0, otherHullClone.ToString());
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{
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int iBase, iOther;
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// Insert into baseHull
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for (iBase = 0; iBase < baseHullClone.vertices.Count; iBase++)
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{
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int iBaseNext = (iBase + 1) % baseHullClone.vertices.Count;
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Simplex sBase = new Simplex(baseHullClone.vertices[iBase], baseHullClone.vertices[iBaseNext]);
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for (iOther = 0; iOther < otherHullClone.vertices.Count; iOther++)
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{
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int iOtherNext = (iOther + 1) % otherHullClone.vertices.Count;
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Simplex sOther = new Simplex(otherHullClone.vertices[iOther], otherHullClone.vertices[iOtherNext]);
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Manager.PhysicsVector intersect = Simplex.Intersect(sBase, sOther, 0.001f, -.001f, 0.999f, 1.001f);
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if (intersect != null)
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{
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Vertex vIntersect = new Vertex(intersect);
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baseHullClone.vertices.Insert(iBase + 1, vIntersect);
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sBase.v2 = vIntersect;
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intersects = true;
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}
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}
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}
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}
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MainLog.Instance.Debug("State after intersection detection for the base hull");
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MainLog.Instance.Debug("The baseHull is:\n{1}", 0, baseHullClone.ToString());
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{
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int iOther, iBase;
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// Insert into otherHull
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for (iOther = 0; iOther < otherHullClone.vertices.Count; iOther++)
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{
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int iOtherNext = (iOther + 1) % otherHullClone.vertices.Count;
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Simplex sOther = new Simplex(otherHullClone.vertices[iOther], otherHullClone.vertices[iOtherNext]);
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for (iBase = 0; iBase < baseHullClone.vertices.Count; iBase++)
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{
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int iBaseNext = (iBase + 1) % baseHullClone.vertices.Count;
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Simplex sBase = new Simplex(baseHullClone.vertices[iBase], baseHullClone.vertices[iBaseNext]);
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Manager.PhysicsVector intersect = Simplex.Intersect(sBase, sOther, -.001f, 0.001f, 1.001f, 0.999f);
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if (intersect != null)
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{
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Vertex vIntersect = new Vertex(intersect);
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otherHullClone.vertices.Insert(iOther + 1, vIntersect);
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sOther.v2 = vIntersect;
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intersects = true;
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}
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}
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}
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}
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MainLog.Instance.Debug("State after intersection detection for the base hull");
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MainLog.Instance.Debug("The otherHull is:\n{1}", 0, otherHullClone.ToString());
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bool otherIsInBase = baseHullClone.containsPointsFrom(otherHullClone);
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if (!intersects && otherIsInBase)
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{
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// We have a hole here
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baseHullClone.holeVertices = otherHullClone.vertices;
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return baseHullClone;
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}
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SimpleHull result = new SimpleHull();
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// Find a good starting Simplex from baseHull
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// A good starting simplex is one that is outside otherHull
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// Such a simplex must exist, otherwise the result will be empty
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Vertex baseStartVertex = null;
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{
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int iBase;
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for (iBase = 0; iBase < baseHullClone.vertices.Count; iBase++)
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{
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int iBaseNext = (iBase + 1) % baseHullClone.vertices.Count;
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Vertex center = new Vertex((baseHullClone.vertices[iBase] + baseHullClone.vertices[iBaseNext]) / 2.0f);
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bool isOutside = !otherHullClone.IsPointIn(center);
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if (isOutside)
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{
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baseStartVertex = baseHullClone.vertices[iBaseNext];
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break;
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}
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}
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}
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if (baseStartVertex == null) // i.e. no simplex fulfilled the "outside" condition.
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// In otherwords, subtractHull completely embraces baseHull
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{
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return result;
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}
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// The simplex that *starts* with baseStartVertex is outside the cutting hull,
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// so we can start our walk with the next vertex without loosing a branch
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Vertex V1 = baseStartVertex;
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bool onBase = true;
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// And here is how we do the magic :-)
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// Start on the base hull.
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// Walk the vertices in the positive direction
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// For each vertex check, whether it is a vertex shared with the other hull
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// if this is the case, switch over to walking the other vertex list.
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// Note: The other hull *must* go backwards to our starting point (via several orther vertices)
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// Thus it is important that the cutting hull has the inverse directional sense than the
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// base hull!!!!!!!!! (means if base goes CW around it's center cutting hull must go CCW)
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bool done = false;
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while (!done)
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{
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result.AddVertex(V1);
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Vertex nextVertex = null;
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if (onBase)
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{
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nextVertex = otherHullClone.FindVertex(V1, 0.001f);
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}
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else
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{
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nextVertex = baseHullClone.FindVertex(V1, 0.001f);
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}
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if (nextVertex != null) // A node that represents an intersection
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{
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V1 = nextVertex; // Needed to find the next vertex on the other hull
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onBase = !onBase;
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}
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if (onBase)
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V1 = baseHullClone.getNextVertex(V1);
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else
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V1 = otherHullClone.getNextVertex(V1);
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if (V1 == baseStartVertex)
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done = true;
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}
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MainLog.Instance.Debug("The resulting Hull is:\n{1}", 0, result.ToString());
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return result;
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}
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}
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}
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