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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 (2010/10/01)
#ifndef WM5CREATECLODMESH_H
#define WM5CREATECLODMESH_H
#include "Wm5CollapseRecord.h"
#include "Wm5EdgeKey.h"
#include "Wm5MinHeap.h"
#include "Wm5TriangleKey.h"
#include "Wm5TriMesh.h"
// CreateClodMesh computes an array of CollapseRecord that represents edge
// collapses in a triangle mesh. An edge <V0,V1> is collapsed by replacing
// V1 (the "throw" vertex) by V0 (the "keep" vertex). No new vertices or
// surface attributes are introduced. Moreover, the vertex and index buffers
// are reordered so that vertices and triangles that are removed first in the
// collapse process occur at the ends of their arrays. This supports sending
// the vertices as static geometry to the hardware renderer. The level of
// detail selection only needs to (1) change the active vertex and triangle
// counts, and (2) update the index buffer based on the CollapseRecord
// index values.
//
// Some lighting artifacts may occur when normal vectors are present in the
// vertex buffer. The artifacts can be reduced if the normals are
// recalculated using the triangle topology of the index buffer each time
// the target record changes. In this case, the vertex buffer becomes
// dynamic, so you have to tell the renderer to update the video memory
// copy each frame.
//
// The CollapseRecord class can be modified to store new vertices and
// attributes for incremental updates. For example, you might want to
// replace V0 and V1 by (V0+V1)/2, and then average their corresponding
// attributes. In this case, the vertex buffer becomes dynamic, and you have
// to tell the renderer to update the video memory copy each frame.
#include "Wm5GraphicsLIB.h"
namespace Wm5
{
class WM5_GRAPHICS_ITEM CreateClodMesh
{
public:
// Construction and destruction.
CreateClodMesh (TriMesh* mesh, int& numRecords, CollapseRecord*& records);
~CreateClodMesh ();
private:
// Vertex-edge-triangle graph.
typedef std::set<TriangleKey> TriangleKeySet;
typedef std::set<EdgeKey> EdgeKeySet;
class Vertex
{
public:
Vertex ();
EdgeKeySet AdjEdges;
TriangleKeySet AdjTriangles;
bool Collapsible;
};
class Edge
{
public:
Edge ();
TriangleKeySet AdjTriangles;
const MinHeapRecord<EdgeKey,float>* Record;
};
typedef int Triangle;
typedef std::vector<Vertex> VertexArray;
typedef std::map<EdgeKey,Edge> EdgeMap;
typedef std::map<TriangleKey,Triangle> TriangleMap;
// Information about the edge collapse.
class CollapseInfo
{
public:
CollapseInfo (int vKeep = -1, int vThrow = -1);
int VKeep, VThrow, TThrow0, TThrow1;
};
bool ValidBuffers () const;
void InsertTriangle (const TriangleKey& tKey, Triangle t);
void RemoveTriangle (const TriangleKey& tKey);
void ClassifyCollapsibleVertices ();
float ComputeMetric (const EdgeKey& eKey);
int CanCollapse (const EdgeKey& eKey);
void Collapse (const EdgeKey& eKey, int indexThrow);
bool ValidResults ();
void ReorderBuffers ();
void ComputeRecords (int& numRecords, CollapseRecord*& records);
// Triangle mesh to be decimated.
int mNumVertices, mNumIndices, mNumTriangles;
int* mIndices;
VertexBufferAccessor mVBA;
// The vertex-edge-triangle graph.
VertexArray mVertices;
EdgeMap mEdges;
TriangleMap mTriangles;
// The edge heap to support collapse operations.
MinHeap<EdgeKey,float> mHeap;
// The sequence of edge collapses.
std::vector<CollapseInfo> mCollapses;
// Postprocessing of the edge collapses.
std::vector<int> mVerticesRemaining;
std::vector<int> mTrianglesRemaining;
};
}
#endif
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