Added Stan Melax Convex Hull utility under Zlib license, Thanks Stan!

Use this Convex Hull to create a renderable shape, using btHullShape, Thanks to John McCutchan

src/LinearMath/btConvexHull.h

@@ -0,0 +1,143 @@
+
+/*
+Stan Melax Convex Hull Computation
+Copyright (c) 2008 Stan Melax http://www.melax.com/
+
+This software is provided 'as-is', without any express or implied warranty.
+In no event will the authors be held liable for any damages arising from the use of this software.
+Permission is granted to anyone to use this software for any purpose, 
+including commercial applications, and to alter it and redistribute it freely, 
+subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+*/
+
+///includes modifications/improvements by John Ratcliff, see BringOutYourDead below.
+
+#ifndef CD_HULL_H
+#define CD_HULL_H
+
+class HullResult
+{
+public:
+	HullResult(void)
+	{
+		mPolygons = true;
+		mNumOutputVertices = 0;
+		mOutputVertices = 0;
+		mNumFaces = 0;
+		mNumIndices = 0;
+		mIndices = 0;
+	}
+	bool                    mPolygons;                  // true if indices represents polygons, false indices are triangles
+	unsigned int            mNumOutputVertices;         // number of vertices in the output hull
+	float                  *mOutputVertices;            // array of vertices, 3 floats each x,y,z
+	unsigned int            mNumFaces;                  // the number of faces produced
+	unsigned int            mNumIndices;                // the total number of indices
+	unsigned int           *mIndices;                   // pointer to indices.
+
+// If triangles, then indices are array indexes into the vertex list.
+// If polygons, indices are in the form (number of points in face) (p1, p2, p3, ..) etc..
+};
+
+enum HullFlag
+{
+	QF_TRIANGLES         = (1<<0),             // report results as triangles, not polygons.
+	QF_REVERSE_ORDER     = (1<<1),             // reverse order of the triangle indices.
+	QF_SKIN_WIDTH        = (1<<2),             // extrude hull based on this skin width
+	QF_DEFAULT           = 0
+};
+
+
+class HullDesc
+{
+public:
+	HullDesc(void)
+	{
+		mFlags          = QF_DEFAULT;
+		mVcount         = 0;
+		mVertices       = 0;
+		mVertexStride   = sizeof(float)*3;
+		mNormalEpsilon  = 0.001f;
+		mMaxVertices		= 4096; // maximum number of points to be considered for a convex hull.
+		mMaxFaces				= 4096;
+		mSkinWidth			= 0.01f; // default is one centimeter
+	};
+
+	HullDesc(HullFlag flag,
+					 unsigned int vcount,
+					 const float *vertices,
+					 unsigned int stride)
+	{
+		mFlags          = flag;
+		mVcount         = vcount;
+		mVertices       = vertices;
+		mVertexStride   = stride;
+		mNormalEpsilon  = 0.001f;
+		mMaxVertices    = 4096;
+		mSkinWidth = 0.01f; // default is one centimeter
+	}
+
+	bool HasHullFlag(HullFlag flag) const
+	{
+		if ( mFlags & flag ) return true;
+		return false;
+	}
+
+	void SetHullFlag(HullFlag flag)
+	{
+		mFlags|=flag;
+	}
+
+	void ClearHullFlag(HullFlag flag)
+	{
+		mFlags&=~flag;
+	}
+
+	unsigned int      mFlags;           // flags to use when generating the convex hull.
+	unsigned int      mVcount;          // number of vertices in the input point cloud
+	const float      *mVertices;        // the array of vertices.
+	unsigned int      mVertexStride;    // the stride of each vertex, in bytes.
+	float             mNormalEpsilon;   // the epsilon for removing duplicates.  This is a normalized value, if normalized bit is on.
+	float             mSkinWidth;
+	unsigned int      mMaxVertices;               // maximum number of vertices to be considered for the hull!
+	unsigned int      mMaxFaces;
+};
+
+enum HullError
+{
+	QE_OK,            // success!
+	QE_FAIL           // failed.
+};
+
+class HullLibrary
+{
+public:
+
+	HullError CreateConvexHull(const HullDesc       &desc,           // describes the input request
+															HullResult           &result);        // contains the resulst
+
+	HullError ReleaseResult(HullResult &result); // release memory allocated for this result, we are done with it.
+
+private:
+
+	//BringOutYourDead (John Ratcliff): When you create a convex hull you hand it a large input set of vertices forming a 'point cloud'. 
+	//After the hull is generated it give you back a set of polygon faces which index the *original* point cloud.
+	//The thing is, often times, there are many 'dead vertices' in the point cloud that are on longer referenced by the hull.
+	//The routine 'BringOutYourDead' find only the referenced vertices, copies them to an new buffer, and re-indexes the hull so that it is a minimal representation.
+	void BringOutYourDead(const float *verts,unsigned int vcount, float *overts,unsigned int &ocount,unsigned int *indices,unsigned indexcount);
+
+	bool    CleanupVertices(unsigned int svcount,
+													const float *svertices,
+													unsigned int stride,
+													unsigned int &vcount,       // output number of vertices
+													float *vertices,                 // location to store the results.
+													float  normalepsilon,
+													float *scale);
+};
+
+
+#endif
+