ScienceLab.UniformLinearMotion/Assets/Scripts/Lesson_1/ApplyDissolveShaderToTerrain.cs

using UnityEngine;

[RequireComponent (typeof(Terrain))]
public class ApplyDissolveShaderToTerrain : MonoBehaviour
{
    public Terrain terrain;
    public float dissolveAmount = 0f;
    public Shader shader;

    private Material originalMaterial;
    private Material overrideMaterial;

    void Start()
    {
        terrain = GetComponent<Terrain>();
        overrideMaterial = new Material(shader);
        originalMaterial = terrain.materialTemplate;
        SetOriginalMaterial();
    }

    private void Update()
    {
        terrain.materialTemplate.SetFloat("_dissolveAmount", dissolveAmount);
    }

    public void SetOriginalMaterial()
    {
        terrain.materialTemplate = originalMaterial;
    }

    public void SetOverrideMaterial()
    {
        terrain.materialTemplate = overrideMaterial;
    }
}