Terrain.treeBillboardDistance

설명

Distance from the camera where trees will be rendered as billboards only.

Decreasing this value improves performance but makes the transition look worse because the difference between billboards and trees will be more obvious.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    void Start() {
        Terrain.activeTerrain.treeBillboardDistance = 100;
    }
}