From cb07ba0d68eeb57bae1cb60f387483ff720cc29d Mon Sep 17 00:00:00 2001
From: Teravus Ovares
Date: Sat, 10 Nov 2007 19:13:52 +0000
Subject: * Moves the Meshmerizer to a separate plugin * Experimental.   Linux
 Prebuild needs testing. * One more update after this to remove the ODEMeshing
 directory....

---
 OpenSim/Region/Physics/Meshing/SimpleHull.cs | 363 +++++++++++++++++++++++++++
 1 file changed, 363 insertions(+)
 create mode 100644 OpenSim/Region/Physics/Meshing/SimpleHull.cs

(limited to 'OpenSim/Region/Physics/Meshing/SimpleHull.cs')

diff --git a/OpenSim/Region/Physics/Meshing/SimpleHull.cs b/OpenSim/Region/Physics/Meshing/SimpleHull.cs
new file mode 100644
index 0000000..c199949
--- /dev/null
+++ b/OpenSim/Region/Physics/Meshing/SimpleHull.cs
@@ -0,0 +1,363 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+using OpenSim.Framework.Console;
+
+namespace OpenSim.Region.Physics.Meshing
+{
+    // A simple hull is a set of vertices building up to simplices that border a region
+    // The word simple referes to the fact, that this class assumes, that all simplices
+    // do not intersect
+    // Simple hulls can be added and subtracted.
+    // Vertices can be checked to lie inside a hull
+    // Also note, that the sequence of the vertices is important and defines if the region that
+    // is defined by the hull lies inside or outside the simplex chain
+    public class SimpleHull
+    {
+        List<Vertex> vertices = new List<Vertex>();
+        List<Vertex> holeVertices = new List<Vertex>(); // Only used, when the hull is hollow
+
+        // Adds a vertex to the end of the list
+        public void AddVertex(Vertex v) {
+            vertices.Add(v);
+        }
+
+        override public String ToString()
+        {
+            String result="";
+            foreach (Vertex v in vertices)
+            {
+                result += "b:" + v.ToString() + "\n";
+            }
+
+            return result;
+        }
+
+
+        public List<Vertex> getVertices() {
+            List<Vertex> newVertices = new List<Vertex>();
+
+            newVertices.AddRange(vertices);
+            newVertices.Add(null);
+            newVertices.AddRange(holeVertices);
+
+            return newVertices;
+        }
+
+        public SimpleHull Clone()
+        {
+            SimpleHull result = new SimpleHull();
+            foreach (Vertex v in vertices)
+            {
+                result.AddVertex(v.Clone());
+            }
+
+            foreach (Vertex v in this.holeVertices)
+            {
+                result.holeVertices.Add(v.Clone());
+            }
+            
+            return result;
+        }
+
+        public bool IsPointIn(Vertex v1)
+        {
+            int iCounter=0;
+            List<Simplex> simplices=buildSimplexList();
+            foreach (Simplex s in simplices)
+            {
+                // Send a ray along the positive X-Direction
+                // Note, that this direction must correlate with the "below" interpretation
+                // of handling for the special cases below
+                Manager.PhysicsVector intersection = s.RayIntersect(v1, new Manager.PhysicsVector(1.0f, 0.0f, 0.0f), true);
+
+                if (intersection == null)
+                    continue;   // No intersection. Done. More tests to follow otherwise
+
+                // Did we hit the end of a simplex?
+                // Then this can be one of two special cases:
+                // 1. we go through a border exactly at a joint
+                // 2. we have just marginally touched a corner
+                // 3. we can slide along a border
+                // Solution: If the other vertex is "below" the ray, we don't count it
+                // Thus corners pointing down are counted twice, corners pointing up are not counted
+                // borders are counted once
+                if (intersection.IsIdentical(s.v1, 0.001f)) {
+                    if (s.v2.Y < v1.Y)
+                        continue;
+                }
+                // Do this for the other vertex two
+                if (intersection.IsIdentical(s.v2, 0.001f)) {
+                    if (s.v1.Y<v1.Y)
+                        continue;
+                }
+                iCounter++;
+            }
+
+            return iCounter % 2 == 1; // Point is inside if the number of intersections is odd
+        }
+
+        public bool containsPointsFrom(SimpleHull otherHull)
+        {
+            foreach (Vertex v in otherHull.vertices)
+            {
+                if (IsPointIn(v))
+                    return true;
+            }
+
+            return false;
+        }
+
+
+        List<Simplex> buildSimplexList() {
+
+            List<Simplex> result = new List<Simplex>();
+
+            // Not asserted but assumed: at least three vertices
+            for (int i=0; i<vertices.Count-1; i++) {
+                Simplex s=new Simplex(vertices[i], vertices[i+1]);
+                result.Add(s);
+            }
+            Simplex s1=new Simplex(vertices[vertices.Count-1], vertices[0]);
+            result.Add(s1);
+
+            if (holeVertices.Count==0)
+                return result;
+
+            // Same here. At least three vertices in hole assumed
+            for (int i = 0; i < holeVertices.Count - 1; i++)
+            {
+                Simplex s = new Simplex(holeVertices[i], holeVertices[i + 1]);
+                result.Add(s);
+            }
+            
+            s1 = new Simplex(holeVertices[holeVertices.Count - 1], holeVertices[0]);
+            result.Add(s1);
+            return result;
+        }
+
+        bool InsertVertex(Vertex v, int iAfter)
+        {
+            vertices.Insert(iAfter + 1, v);
+            return true;
+        }
+
+        Vertex getNextVertex(Vertex currentVertex)
+        {
+            int iCurrentIndex;
+            iCurrentIndex = vertices.IndexOf(currentVertex);
+
+            // Error handling for iCurrentIndex==-1 should go here (and probably never will)
+
+            iCurrentIndex++;
+            if (iCurrentIndex == vertices.Count)
+                iCurrentIndex = 0;
+
+            return vertices[iCurrentIndex];
+        }
+
+        public Vertex FindVertex(Vertex vBase, float tolerance) {
+            foreach (Vertex v in vertices) {
+                if (v.IsIdentical(vBase, tolerance))
+                    return v;
+            }
+
+            return null;
+        }
+
+        public void FindIntersection(Simplex s, ref Vertex Intersection, ref Vertex nextVertex)
+        {
+            Vertex bestIntersection=null;
+            float distToV1=Single.PositiveInfinity;
+            Simplex bestIntersectingSimplex=null;
+
+            List<Simplex> simple = buildSimplexList();
+            foreach (Simplex sTest in simple)
+            {
+                Manager.PhysicsVector vvTemp = Simplex.Intersect(sTest, s, -.001f, -.001f, 0.999f, .999f);
+                
+                Vertex vTemp=null;
+                if (vvTemp != null)
+                    vTemp = new Vertex(vvTemp);
+
+                if (vTemp!=null) {
+
+                    Manager.PhysicsVector diff=(s.v1-vTemp);
+                    float distTemp=diff.length();
+
+                    if (bestIntersection==null || distTemp<distToV1) {
+                        bestIntersection=vTemp;
+                        distToV1=distTemp;
+                        bestIntersectingSimplex = sTest;
+                    }
+
+                } // end if vTemp
+
+            } // end foreach
+
+            Intersection = bestIntersection;
+            if (bestIntersectingSimplex != null)
+                nextVertex = bestIntersectingSimplex.v2;
+            else
+                nextVertex = null;
+        }
+
+
+        public static SimpleHull SubtractHull(SimpleHull baseHull, SimpleHull otherHull)
+        {
+
+            SimpleHull baseHullClone = baseHull.Clone();
+            SimpleHull otherHullClone = otherHull.Clone();
+            bool intersects = false;
+
+            MainLog.Instance.Debug("State before intersection detection");
+            MainLog.Instance.Debug("The baseHull is:\n{1}", 0, baseHullClone.ToString());
+            MainLog.Instance.Debug("The otherHull is:\n{1}", 0, otherHullClone.ToString());
+
+            {
+                int iBase, iOther;
+
+                // Insert into baseHull
+                for (iBase = 0; iBase < baseHullClone.vertices.Count; iBase++)
+                {
+                    int iBaseNext = (iBase + 1) % baseHullClone.vertices.Count;
+                    Simplex sBase = new Simplex(baseHullClone.vertices[iBase], baseHullClone.vertices[iBaseNext]);
+
+                    for (iOther = 0; iOther < otherHullClone.vertices.Count; iOther++)
+                    {
+                        int iOtherNext = (iOther + 1) % otherHullClone.vertices.Count;
+                        Simplex sOther = new Simplex(otherHullClone.vertices[iOther], otherHullClone.vertices[iOtherNext]);
+
+                        Manager.PhysicsVector intersect = Simplex.Intersect(sBase, sOther, 0.001f, -.001f, 0.999f, 1.001f);
+                        if (intersect != null)
+                        {
+                            Vertex vIntersect = new Vertex(intersect);
+                            baseHullClone.vertices.Insert(iBase + 1, vIntersect);
+                            sBase.v2 = vIntersect;
+                            intersects = true;
+                        }
+                    }
+                }
+            }
+
+            MainLog.Instance.Debug("State after intersection detection for the base hull");
+            MainLog.Instance.Debug("The baseHull is:\n{1}", 0, baseHullClone.ToString());
+
+            {
+                int iOther, iBase;
+
+                // Insert into otherHull
+                for (iOther = 0; iOther < otherHullClone.vertices.Count; iOther++)
+                {
+                    int iOtherNext = (iOther + 1) % otherHullClone.vertices.Count;
+                    Simplex sOther = new Simplex(otherHullClone.vertices[iOther], otherHullClone.vertices[iOtherNext]);
+
+                    for (iBase = 0; iBase < baseHullClone.vertices.Count; iBase++)
+                    {
+                        int iBaseNext = (iBase + 1) % baseHullClone.vertices.Count;
+                        Simplex sBase = new Simplex(baseHullClone.vertices[iBase], baseHullClone.vertices[iBaseNext]);
+
+                        Manager.PhysicsVector intersect = Simplex.Intersect(sBase, sOther, -.001f, 0.001f, 1.001f, 0.999f);
+                        if (intersect != null)
+                        {
+                            Vertex vIntersect = new Vertex(intersect);
+                            otherHullClone.vertices.Insert(iOther + 1, vIntersect);
+                            sOther.v2 = vIntersect;
+                            intersects = true;
+                        }
+                    }
+                }
+            }
+
+            MainLog.Instance.Debug("State after intersection detection for the base hull");
+            MainLog.Instance.Debug("The otherHull is:\n{1}", 0, otherHullClone.ToString());
+
+
+            bool otherIsInBase = baseHullClone.containsPointsFrom(otherHullClone);
+            if (!intersects && otherIsInBase)
+            {
+                // We have a hole here
+                baseHullClone.holeVertices = otherHullClone.vertices;
+                return baseHullClone;
+            }
+
+
+            SimpleHull result = new SimpleHull();
+
+            // Find a good starting Simplex from baseHull
+            // A good starting simplex is one that is outside otherHull
+            // Such a simplex must exist, otherwise the result will be empty
+            Vertex baseStartVertex = null;
+            {
+                int iBase;
+                for (iBase = 0; iBase < baseHullClone.vertices.Count; iBase++)
+                {
+                    int iBaseNext = (iBase + 1) % baseHullClone.vertices.Count;
+                    Vertex center = new Vertex((baseHullClone.vertices[iBase] + baseHullClone.vertices[iBaseNext]) / 2.0f);
+                    bool isOutside = !otherHullClone.IsPointIn(center);
+                    if (isOutside)
+                    {
+                        baseStartVertex = baseHullClone.vertices[iBaseNext];
+                        break;
+                    }
+                }
+            }
+
+
+            if (baseStartVertex == null) // i.e. no simplex fulfilled the "outside" condition. 
+            // In otherwords, subtractHull completely embraces baseHull
+            {
+                return result;
+            }
+
+            // The simplex that *starts* with baseStartVertex is outside the cutting hull,
+            // so we can start our walk with the next vertex without loosing a branch
+            Vertex V1 = baseStartVertex;
+            bool onBase = true;
+
+            // And here is how we do the magic :-)
+            // Start on the base hull.
+            // Walk the vertices in the positive direction
+            // For each vertex check, whether it is a vertex shared with the other hull
+            // if this is the case, switch over to walking the other vertex list.
+            // Note: The other hull *must* go backwards to our starting point (via several orther vertices)
+            // Thus it is important that the cutting hull has the inverse directional sense than the
+            // base hull!!!!!!!!! (means if base goes CW around it's center cutting hull must go CCW)
+
+            bool done = false;
+            while (!done)
+            {
+                result.AddVertex(V1);
+                Vertex nextVertex = null;
+                if (onBase)
+                {
+                    nextVertex = otherHullClone.FindVertex(V1, 0.001f);
+                }
+                else
+                {
+                    nextVertex = baseHullClone.FindVertex(V1, 0.001f);
+                }
+
+                if (nextVertex != null) // A node that represents an intersection
+                {
+                    V1 = nextVertex;    // Needed to find the next vertex on the other hull
+                    onBase = !onBase;
+                }
+
+                if (onBase)
+                    V1 = baseHullClone.getNextVertex(V1);
+                else
+                    V1 = otherHullClone.getNextVertex(V1);
+
+                if (V1 == baseStartVertex)
+                    done = true;
+            }
+
+            MainLog.Instance.Debug("The resulting Hull is:\n{1}", 0, result.ToString());
+
+            return result;
+
+        }
+    }
+}
-- 
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