DynamicCreateMesh3.cs

using UnityEngine;
using System.Collections;

/// <summary>
/// 頂点カラーで三角形を描画します
/// </summary>
[RequireComponent (typeof(MeshRenderer))]
[RequireComponent (typeof(MeshFilter))]
public class DynamicCreateMesh : MonoBehaviour
{
  [SerializeField]
  private Material _mat;

  private void Start ()
  {
    var mesh = new Mesh ();
    mesh.vertices = new Vector3[] {
      new Vector3 (0, 1f),
      new Vector3 (1f, -1f),
      new Vector3 (-1f, -1f),
    };
    mesh.triangles = new int[] {
      0, 1, 2	
    };

    // 変更箇所 : 各頂点に色情報を設定
    mesh.colors = new Color[] {
      Color.white,
      Color.red,
      Color.green
    };

    var filter = GetComponent<MeshFilter> ();
    filter.sharedMesh = mesh;

    var renderer = GetComponent<MeshRenderer> ();
    renderer.material = _mat;
  }
}