86 lines
2.6 KiB
C#
86 lines
2.6 KiB
C#
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// -----------------------------------------------------------------------
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// <copyright file="TriangleSampler.cs">
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// Original Triangle code by Jonathan Richard Shewchuk, http://www.cs.cmu.edu/~quake/triangle.html
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// Triangle.NET code by Christian Woltering, http://triangle.codeplex.com/
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// </copyright>
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// -----------------------------------------------------------------------
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namespace TriangleNet
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{
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using System;
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using System.Collections.Generic;
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using TriangleNet.Topology;
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/// <summary>
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/// Used for triangle sampling in the <see cref="TriangleLocator"/> class.
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/// </summary>
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class TriangleSampler : IEnumerable<Triangle>
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{
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private const int RANDOM_SEED = 110503;
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// Empirically chosen factor.
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private const int samplefactor = 11;
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private Random random;
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private Mesh mesh;
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// Number of random samples for point location (at least 1).
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private int samples = 1;
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// Number of triangles in mesh.
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private int triangleCount = 0;
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public TriangleSampler(Mesh mesh)
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: this(mesh, new Random(RANDOM_SEED))
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{
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}
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public TriangleSampler(Mesh mesh, Random random)
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{
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this.mesh = mesh;
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this.random = random;
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}
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/// <summary>
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/// Reset the sampler.
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/// </summary>
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public void Reset()
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{
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this.samples = 1;
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this.triangleCount = 0;
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}
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/// <summary>
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/// Update sampling parameters if mesh changed.
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/// </summary>
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public void Update()
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{
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int count = mesh.triangles.Count;
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if (triangleCount != count)
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{
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triangleCount = count;
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// The number of random samples taken is proportional to the cube root
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// of the number of triangles in the mesh. The next bit of code assumes
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// that the number of triangles increases monotonically (or at least
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// doesn't decrease enough to matter).
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while (samplefactor * samples * samples * samples < count)
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{
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samples++;
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}
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}
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}
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public IEnumerator<Triangle> GetEnumerator()
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{
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return mesh.triangles.Sample(samples, random).GetEnumerator();
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}
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System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
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{
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return GetEnumerator();
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}
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}
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}
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