Create a mesh from a Playground Spline

playground-mesh-spline.cs

using UnityEngine;
using System.Collections;
 
namespace PlaygroundSplines {
        /// <summary>
        /// The PlaygroundSplineMesh class lets you create a mesh from a Playground Spline.
        /// </summary>
        [ExecuteInEditMode()]
        public class PlaygroundSplineMesh : MonoBehaviour {
 
                public PlaygroundSpline spline;
                [Range(2,1000)]
                public int points = 100;
                [Range(.01f, 100f)]
                public float width = 1f;
 
                int prevPoints;
                float prevWidth;
 
                void OnEnable ()
                {
                        if (GetComponent<Renderer>() == null)
                                gameObject.AddComponent<MeshRenderer>();
                        if (spline == null)
                                spline = GetComponent<PlaygroundSpline>();
                        if (spline != null)
                                BuildSplineMesh(spline, points, width);
                        prevPoints = points;
                        prevWidth = width;
                }
 
                void Update ()
                {
                        if (prevPoints!=points || prevWidth!=width)
                        {
                                if (spline != null)
                                        BuildSplineMesh(spline, points, width);
                                prevPoints = points;
                                prevWidth = width;
                        }
                }
               
                public void BuildSplineMesh (PlaygroundSpline spline, int points, float width)
                {
                        if (points<2)
                                points = 2;
                        int totalVertices = points*2;
                        MeshFilter _mf = GetComponent<MeshFilter>()!=null? GetComponent<MeshFilter>() : gameObject.AddComponent<MeshFilter>();
                        Mesh _m = new Mesh();
                        Vector3[] verts = new Vector3[totalVertices];
                        Vector2[] uvs = new Vector2[totalVertices];
                        int[] tris = new int[(points-1)*6];
 
                        // Construct the mesh
                        for (int i = 0; i<points; i++)
                        {
                                // Create a normalized time value
                                float t = (i*1f)/(points-1);
                                float tNext = ((i*1f)+1)/(points-1);
                                if (t>=1)
                                        t = .9999f;
                                if (tNext>=1)
                                        tNext = .99999f;
 
                                // Get the current and next position from the spline on time
                                Vector3 currentPosition = spline.GetPoint (t);
                                Vector3 nextPosition = spline.GetPoint (tNext);
 
                                // Raycast down to determine up direction (especially practical for roads / rivers)
                                RaycastHit hit;
                                Vector3 up = Vector3.up;
                                if (Physics.Raycast (currentPosition, Vector3.down, out hit))
                                    up = hit.normal;
 
                                // Create two width point references based on current and next position
                                Vector3 dir = (Vector3.Cross(up, nextPosition - currentPosition)).normalized;
                                Vector3 lPoint = currentPosition + dir * (width/2);
                                Vector3 rPoint = currentPosition - dir * (width/2);
 
                                // Draw debug
                                Debug.DrawLine(lPoint, rPoint);
 
                                verts[i*2] = lPoint;
                                verts[(i*2)+1] = rPoint;
                                uvs[i*2] = new Vector2(t,0);
                                uvs[(i*2)+1] = new Vector2(t,1f);
 
                                if (i>0)
                                {
                                        int triIndex = (i-1)*6;
                                        int vertIndex = i*2;
 
                                        tris[triIndex] = vertIndex-2;
                                        tris[triIndex+1] = vertIndex-1;
                                        tris[triIndex+2] = vertIndex;
                                        tris[triIndex+3] = vertIndex;
                                        tris[triIndex+4] = vertIndex-1;
                                        tris[triIndex+5] = vertIndex+1;
                                }
                        }
 
                        // Assign the data to the mesh
                        _m.vertices = verts;
                        _m.uv = uvs;
                        _m.triangles = tris;
                        _m.RecalculateNormals();
 
                        // Assign the mesh to the MeshFilter
                        _mf.mesh = _m;
                }
        }
}

Source: http://pastebin.com/aJ4tvsVx