82 lines
3.2 KiB
C#
82 lines
3.2 KiB
C#
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using System.Collections.Generic;
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using UnityEngine;
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using BrainFailProductions.PolyFew.AsImpL.MathUtil;
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namespace BrainFailProductions.PolyFew.AsImpL
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{
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/// <summary>
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/// Implements triangulation of a face of a data set.
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/// </summary>
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public static class Triangulator
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{
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/// <summary>
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/// Triangulate a face of the given dataset.
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/// </summary>
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/// <param name="dataSet">Input data set.</param>
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/// <param name="face">Face to be triangulated (with more than 3 vertices)</param>
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public static void Triangulate(DataSet dataSet, DataSet.FaceIndices[] face)
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{
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int numVerts = face.Length;
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//Debug.LogFormat("Triangulating a face with {0} vertices of {1}...", numVerts, dataSet.CurrGroupName);
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Vector3 planeNormal = FindPlaneNormal(dataSet, face);
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// setup the data structure used for triangluation
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List<MathUtil.Vertex> poly = new List<MathUtil.Vertex>();
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for (int i = 0; i < numVerts; i++)
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{
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int idx = face[i].vertIdx;
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poly.Add(new MathUtil.Vertex(i, dataSet.vertList[idx]));
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}
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// use the ear clipping triangulation
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List<MathUtil.Triangle> newTris = Triangulation.TriangulateByEarClipping(poly, planeNormal, dataSet.CurrGroupName);
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// copy the data structure used for triangluation back to the data set
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for (int t = 0; t < newTris.Count; t++)
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{
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int idx1 = newTris[t].v1.OriginalIndex;
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int idx2 = newTris[t].v2.OriginalIndex;
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int idx3 = newTris[t].v3.OriginalIndex;
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dataSet.AddFaceIndices(face[idx1]);
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dataSet.AddFaceIndices(face[idx3]);
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dataSet.AddFaceIndices(face[idx2]);
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}
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}
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/// <summary>
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/// Get a normal of a plane used for polygon projection.
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/// </summary>
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/// <param name="dataSet">Input data set.</param>
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/// <param name="face">Face to be triangulated</param>
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/// <returns>The mean of the normals if available or a vector perpendicular to the first triangle</returns>
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public static Vector3 FindPlaneNormal(DataSet dataSet, DataSet.FaceIndices[] face)
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{
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int vertCount = face.Length;
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bool hasNormals = dataSet.normalList.Count > 0;
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Vector3 planeNormal = Vector3.zero;
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if (hasNormals)
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{
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// if it has normals use the mean of the normals of the vertices
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for (int i = 0; i < vertCount; i++)
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{
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int normalIdx = face[i].normIdx;
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planeNormal += dataSet.normalList[normalIdx];
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}
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planeNormal.Normalize();
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}
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else
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{
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// else calculate a vector perpendicular to the first triangle
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Vector3 v0 = dataSet.vertList[face[0].vertIdx];
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Vector3 v1 = dataSet.vertList[face[1].vertIdx];
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Vector3 vn = dataSet.vertList[face[vertCount - 1].vertIdx];
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planeNormal = MathUtility.ComputeNormal(v0, v1, vn);
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}
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return planeNormal;
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}
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}
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}
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