100 lines
3.4 KiB
C++
100 lines
3.4 KiB
C++
/*
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Copyright (c) 2011 Ole Kniemeyer, MAXON, www.maxon.net
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This software is provided 'as-is', without any express or implied warranty.
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In no event will the authors be held liable for any damages arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it freely,
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subject to the following restrictions:
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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.
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2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#ifndef B3_CONVEX_HULL_COMPUTER_H
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#define B3_CONVEX_HULL_COMPUTER_H
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#include "Bullet3Common/b3Vector3.h"
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#include "Bullet3Common/b3AlignedObjectArray.h"
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/// Convex hull implementation based on Preparata and Hong
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/// See http://code.google.com/p/bullet/issues/detail?id=275
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/// Ole Kniemeyer, MAXON Computer GmbH
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class b3ConvexHullComputer
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{
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private:
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b3Scalar compute(const void* coords, bool doubleCoords, int stride, int count, b3Scalar shrink, b3Scalar shrinkClamp);
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public:
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class Edge
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{
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private:
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int next;
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int reverse;
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int targetVertex;
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friend class b3ConvexHullComputer;
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public:
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int getSourceVertex() const
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{
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return (this + reverse)->targetVertex;
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}
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int getTargetVertex() const
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{
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return targetVertex;
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}
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const Edge* getNextEdgeOfVertex() const // clockwise list of all edges of a vertex
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{
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return this + next;
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}
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const Edge* getNextEdgeOfFace() const // counter-clockwise list of all edges of a face
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{
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return (this + reverse)->getNextEdgeOfVertex();
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}
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const Edge* getReverseEdge() const
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{
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return this + reverse;
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}
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};
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// Vertices of the output hull
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b3AlignedObjectArray<b3Vector3> vertices;
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// Edges of the output hull
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b3AlignedObjectArray<Edge> edges;
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// Faces of the convex hull. Each entry is an index into the "edges" array pointing to an edge of the face. Faces are planar n-gons
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b3AlignedObjectArray<int> faces;
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/*
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Compute convex hull of "count" vertices stored in "coords". "stride" is the difference in bytes
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between the addresses of consecutive vertices. If "shrink" is positive, the convex hull is shrunken
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by that amount (each face is moved by "shrink" length units towards the center along its normal).
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If "shrinkClamp" is positive, "shrink" is clamped to not exceed "shrinkClamp * innerRadius", where "innerRadius"
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is the minimum distance of a face to the center of the convex hull.
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The returned value is the amount by which the hull has been shrunken. If it is negative, the amount was so large
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that the resulting convex hull is empty.
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The output convex hull can be found in the member variables "vertices", "edges", "faces".
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*/
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b3Scalar compute(const float* coords, int stride, int count, b3Scalar shrink, b3Scalar shrinkClamp)
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{
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return compute(coords, false, stride, count, shrink, shrinkClamp);
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}
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// same as above, but double precision
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b3Scalar compute(const double* coords, int stride, int count, b3Scalar shrink, b3Scalar shrinkClamp)
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{
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return compute(coords, true, stride, count, shrink, shrinkClamp);
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}
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};
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#endif //B3_CONVEX_HULL_COMPUTER_H
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