public static Mesh Build(TreeData data, int generations, float length, float radius) { data.Setup(); TreeBranch root = new TreeBranch( generations, length, radius, data ); List <Vector3> vertices = new List <Vector3>(); List <Vector3> normals = new List <Vector3>(); List <Vector4> tangents = new List <Vector4>(); List <Vector2> uvs = new List <Vector2>(); List <int> triangles = new List <int>(); // 木の全長を取得 // 枝の長さを全長で割ることで、uv座標の高さ(uv.y)が // 根元から枝先に至るまで[0.0 ~ 1.0]で変化するように設定する float maxLength = TraverseMaxLength(root); // 再帰的に全ての枝を辿り、一つ一つの枝に対応するMeshを生成する Traverse(root, (TreeBranch branch) => { int offset = vertices.Count; float vOffset = branch.Offset / maxLength; float vLength = branch.Length / maxLength; // 一本の枝から頂点データを生成する for (int i = 0, n = branch.Segments.Count; i < n; i++) { float t = 1f * i / (n - 1); float v = vOffset + vLength * t; TreeSegment segment = branch.Segments[i]; Vector3 N = segment.Frame.Normal; Vector3 B = segment.Frame.Binormal; for (int j = 0; j <= data.radialSegments; j++) { // 0.0 ~ 2π float u = 1f * j / data.radialSegments; float rad = u * PI2; float cos = Mathf.Cos(rad), sin = Mathf.Sin(rad); Vector3 normal = (cos * N + sin * B).normalized; vertices.Add(segment.Position + segment.Radius * normal); normals.Add(normal); Vector3 tangent = segment.Frame.Tangent; tangents.Add(new Vector4(tangent.x, tangent.y, tangent.z, 0f)); uvs.Add(new Vector2(u, v)); } } // 一本の枝の三角形を構築する for (int j = 1; j <= data.heightSegments; j++) { for (int i = 1; i <= data.radialSegments; i++) { int a = (data.radialSegments + 1) * (j - 1) + (i - 1); int b = (data.radialSegments + 1) * j + (i - 1); int c = (data.radialSegments + 1) * j + i; int d = (data.radialSegments + 1) * (j - 1) + i; a += offset; b += offset; c += offset; d += offset; triangles.Add(a); triangles.Add(d); triangles.Add(b); triangles.Add(b); triangles.Add(d); triangles.Add(c); } } }); Mesh mesh = new Mesh(); mesh.vertices = vertices.ToArray(); mesh.normals = normals.ToArray(); mesh.tangents = tangents.ToArray(); mesh.uv = uvs.ToArray(); mesh.triangles = triangles.ToArray(); mesh.RecalculateBounds(); return(mesh); }
protected TreeBranch(int generation, int generations, Vector3 from, Vector3 tangent, Vector3 normal, Vector3 binormal, float length, float radius, float offset, TreeData data) { this.generation = generation; this.fromRadius = radius; // 枝先である場合は先端の太さが0になる this.toRadius = (generation == 0) ? 0f : radius *data.radiusAttenuation; this.from = from; // 枝先ほど分岐する角度が大きくなる float scale = Mathf.Lerp(1f, data.growthAngleScale, 1f - 1f * generation / generations); // normal方向の回転 Quaternion qn = Quaternion.AngleAxis(scale * data.GetRandomGrowthAngle(), normal); // binormal方向の回転 Quaternion qb = Quaternion.AngleAxis(scale * data.GetRandomGrowthAngle(), binormal); // 枝先が向いているtangent方向にqn * qbの回転をかけつつ、枝先の位置を決める this.to = from + (qn * qb) * tangent * length; this.length = length; this.offset = offset; // モデル生成に必要な節を構築 segments = BuildSegments(data, fromRadius, toRadius, normal, binormal); children = new List <TreeBranch>(); if (generation > 0) { // 分岐する数を取得 int count = data.GetRandomBranches(); for (int i = 0; i < count; i++) { float ratio; // [0.0 ~ 1.0] if (count == 1) { // 分岐数が1である場合(0除算を回避) ratio = 1f; } else { ratio = Mathf.Lerp(0.5f, 1f, (1f * i) / (count - 1)); } // 分岐元の節を取得 int index = Mathf.FloorToInt(ratio * (segments.Count - 1)); TreeSegment segment = segments[index]; // 分岐元の節が持つベクトルをTreeBranchに渡すことで滑らかな分岐を得る Vector3 nt = segment.Frame.Tangent; Vector3 nn = segment.Frame.Normal; Vector3 nb = segment.Frame.Binormal; TreeBranch child = new TreeBranch( this.generation - 1, generations, segment.Position, nt, nn, nb, length * Mathf.Lerp(1f, data.lengthAttenuation, ratio), radius * Mathf.Lerp(1f, data.radiusAttenuation, ratio), offset + length, data ); children.Add(child); } } }