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// Geometric Tools, LLC
// Copyright (c) 1998-2014
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
//
// File Version: 5.0.1 (2012/07/07)
#include "VertexCollapse.h"
#include "Wm5DistPoint3Segment3.h"
#include "Wm5Memory.h"
//----------------------------------------------------------------------------
VertexCollapse::VertexCollapse (int numVertices, Vector3f*& vertices,
bool closed, int*& indexMap, int& numEdges, int*& edges)
{
indexMap = new1<int>(numVertices);
if (closed)
{
numEdges = numVertices;
edges = new1<int>(2*numEdges);
if (numVertices == 3)
{
indexMap[0] = 0;
indexMap[1] = 1;
indexMap[2] = 3;
edges[0] = 0; edges[1] = 1;
edges[2] = 1; edges[3] = 2;
edges[4] = 2; edges[5] = 0;
return;
}
}
else
{
numEdges = numVertices - 1;
edges = new1<int>(2*numEdges);
if (numVertices == 2)
{
indexMap[0] = 0;
indexMap[1] = 1;
edges[0] = 0; edges[1] = 1;
return;
}
}
// Create the heap of weights.
mHeap = new0 MinHeap<int, float>(numVertices, 0, Mathf::MAX_REAL);
int qm1 = numVertices - 1;
if (closed)
{
int qm2 = numVertices - 2;
mHeap->Insert(0, GetWeight(qm1, 0, 1, vertices));
mHeap->Insert(qm1, GetWeight(qm2, qm1, 0, vertices));
}
else
{
mHeap->Insert(0, Mathf::MAX_REAL);
mHeap->Insert(qm1, Mathf::MAX_REAL);
}
for (int m = 0, z = 1, p = 2; z < qm1; ++m, ++z, ++p)
{
mHeap->Insert(z, GetWeight(m, z, p, vertices));
}
// Create the level of detail information for the polyline.
int* collapses = new1<int>(numVertices);
CollapseVertices(numVertices, collapses);
ComputeEdges(numVertices, closed, collapses, indexMap, numEdges, edges);
ReorderVertices(numVertices, vertices, collapses, numEdges, edges);
delete1(collapses);
}
//----------------------------------------------------------------------------
VertexCollapse::~VertexCollapse ()
{
delete0(mHeap);
}
//----------------------------------------------------------------------------
float VertexCollapse::GetWeight (int m, int z, int p, Vector3f* vertices)
{
Segment3f segment(vertices[m], vertices[p]);
if (segment.Extent > 0.0f)
{
float distance = DistPoint3Segment3f(vertices[z], segment).Get();
return 0.5f*distance/segment.Extent;
}
return Mathf::MAX_REAL;
}
//----------------------------------------------------------------------------
void VertexCollapse::CollapseVertices (int numVertices, int* collapses)
{
for (int i = numVertices - 1; i >= 0; --i)
{
float weight;
mHeap->Remove(collapses[i], weight);
}
}
//----------------------------------------------------------------------------
void VertexCollapse::ComputeEdges (int numVertices, bool closed,
int* collapses, int* indexMap, int numEdges, int* edges)
{
// Compute the edges (first to collapse is last in array). Do not
// collapse last line segment of open polyline. Do not collapse last
// triangle of closed polyline.
int i, vIndex, eIndex = 2*numEdges - 1;
if (closed)
{
for (i = numVertices - 1; i >= 0; --i)
{
vIndex = collapses[i];
edges[eIndex--] = (vIndex + 1) % numVertices;
edges[eIndex--] = vIndex;
}
}
else
{
for (i = numVertices - 1; i >= 2; --i)
{
vIndex = collapses[i];
edges[eIndex--] = vIndex + 1;
edges[eIndex--] = vIndex;
}
vIndex = collapses[0];
edges[0] = vIndex;
edges[1] = vIndex + 1;
}
// In the given edge order, find the index in the edge array that
// corresponds to a collapse vertex and save the index for the dynamic
// change in level of detail. This relies on the assumption that a
// vertex is shared by at most two edges.
eIndex = 2*numEdges - 1;
for (i = numVertices - 1; i >= 0; --i)
{
vIndex = collapses[i];
for (int e = 0; e < 2*numEdges; ++e)
{
if (vIndex == edges[e])
{
indexMap[i] = e;
edges[e] = edges[eIndex];
break;
}
}
eIndex -= 2;
if (closed)
{
if (eIndex == 5)
{
break;
}
}
else
{
if (eIndex == 1)
{
break;
}
}
}
// Restore the edge array to full level of detail.
if (closed)
{
for (i = 3; i < numVertices; ++i)
{
edges[indexMap[i]] = collapses[i];
}
}
else
{
for (i = 2; i < numVertices; ++i)
{
edges[indexMap[i]] = collapses[i];
}
}
}
//----------------------------------------------------------------------------
void VertexCollapse::ReorderVertices (int numVertices, Vector3f*& vertices,
int* collapses, int numEdges, int* edges)
{
int* permute = new1<int>(numVertices);
Vector3f* permutedVertex = new1<Vector3f>(numVertices);
int i;
for (i = 0; i < numVertices; ++i)
{
int vIndex = collapses[i];
permute[vIndex] = i;
permutedVertex[i] = vertices[vIndex];
}
for (i = 0; i < 2*numEdges; ++i)
{
edges[i] = permute[edges[i]];
}
delete1(permute);
delete1(vertices);
vertices = permutedVertex;
}
//----------------------------------------------------------------------------
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