ChristmasTree.Unity/Assets/TreeGenerator.cs

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class TreeGenerator : MonoBehaviour
{
    public int SliceX;
    public int SliceY;
    public int SliceZ;

    public int RootBranches = 3;

    public Vector3 TrunkSize = Vector3.one;
    private float branchStep;
    public float BranchAngle = 60;

    public ProceduralMeshData GenerateTrunk(Vector3 size){
        ProceduralMeshData m = new ProceduralMeshData();
        BoxGenerator box = new BoxGenerator();
        box.SliceX = SliceX;
        box.SliceY = SliceY;
        box.SliceZ = SliceZ;
        box.Size = size;
        box.Execute(m);

        TransformVertexNode offsetPivot = new TransformVertexNode();
        offsetPivot.Offset = Vector3.forward * size.z * 0.5f;
        offsetPivot.Execute(m);
        return m;
    }



    public void Generate() {
        var mf = GetComponent<MeshFilter>();
        if (mf == null) {
            mf = gameObject.AddComponent<MeshFilter>();
        }

        var mesh = mf.sharedMesh;
        if (mesh == null)
        {
            mesh = new Mesh();
            mf.sharedMesh = mesh;
        }
        branchStep = TrunkSize.z/(RootBranches + 1);

        var mTrunk = GenerateTrunk(TrunkSize);

        List<ProceduralMeshData> branches = new List<ProceduralMeshData>();
        for (int i = 0; i < RootBranches; ++i)
        {
            float zOffset = branchStep*(i + 1);
           

            var branchSize = TrunkSize;
            branchSize.x *= 0.7f;
            branchSize.y *= 0.7f;
            branchSize.z *= Mathf.Pow(0.65f, i + 1) * 0.5f;

            var l = GenerateTrunk(branchSize);
            var r = GenerateTrunk(branchSize);

            TransformVertexNode branchTransform = new TransformVertexNode();
            branchTransform.Rotation = Quaternion.AngleAxis(BranchAngle, Vector3.up);
            branchTransform.Offset = new Vector3(0,0, zOffset);
            branchTransform.Execute(r);

            branchTransform.Rotation = Quaternion.AngleAxis(-BranchAngle, Vector3.up);
            branchTransform.Execute(l);

            branches.Add(l);
            branches.Add(r);
        }


        CombineMeshNode combiner = new CombineMeshNode();
        combiner.Source.Add(mTrunk);
        combiner.Source.AddRange(branches);

        ProceduralMeshData result = new ProceduralMeshData();
        combiner.Execute(result);


        CombineSubmeshesNode submeshCombiner = new CombineSubmeshesNode();
        submeshCombiner.Execute(result);

        result.ApplyToMesh(mesh);
    }
}