1 前言

        选中物体消融特效中基于 Shader 实现了消融特效，本文将基于 Shader Graph 实现消融特效，两者原理一样，只是表达方式不同，另外，选中物体消融特效中通过 discard 丢弃片元，本文通过 alpha 测试丢弃片元。

        Shader Graph环境搭建、简单应用详见→Shader Graph简介。

        本文完整资源见→Unity3D消融特效。

2 消融特效实现

        创建 Unlit Shader Graph，重命名为 DissolveEffect，编辑如下。 

        其中，Alpha 测试需要在 Graph Settings 中开启，如下。

        为实现点击消失效果，需要编写脚本如下。

        DieController.cs

using UnityEngine;
 
public class DieController : MonoBehaviour {
    private RaycastHit hit; // 碰撞信息
 
    private void Start() {
        hit = new RaycastHit();
    }

    private void Update() {
        if (Input.GetMouseButtonUp(0)) {
            GameObject hitObj = GetHitObj();
            if (hitObj != null) {
                GameObject rootObj = GetRootObj(hitObj);
                rootObj.AddComponent<DissolveEffect>();
            }
        }
    }

    private GameObject GetHitObj() { // 获取屏幕射线碰撞的物体
        Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
        if (Physics.Raycast(ray, out hit)) {
            return hit.collider.gameObject;
        }
        return null;
    }

    private GameObject GetRootObj(GameObject obj) { // 获取根对象
        while (obj.transform.parent != null && obj.layer == obj.transform.parent.gameObject.layer) {
            obj = obj.transform.parent.gameObject;
        }
        return obj;
    }
}

        DissolveEffect.cs

using UnityEngine;
 
[DisallowMultipleComponent] // 不允许在同一对象上挂载多个该组件
public class DissolveEffect : MonoBehaviour {
    private Renderer[] renderers; // 渲染器
    private Material dissolveMat; // 消融材质
    private float burnSpeed = 0.25f; // 燃烧速度
    private float burnAmount = 0; // 燃烧量, 值越大模型镂空的越多
 
    private void Awake() {
        dissolveMat = Resources.Load<Material>("DissolveMat");
        renderers = GetComponentsInChildren<Renderer>();
    }

    private void OnEnable() {
        foreach (Renderer renderer in renderers) {
            Material[] materials = renderer.sharedMaterials;
            Material[] dissolveMaterials = new Material[materials.Length];
            for (int i = 0; i < materials.Length; i++) {
                Material newMaterial = new Material(dissolveMat);
                SetTexture(materials[i], newMaterial);
                SetColor(materials[i], newMaterial);
                newMaterial.SetFloat("_BurnAmount", 0);
                dissolveMaterials[i] = newMaterial;
            }
            renderer.sharedMaterials = dissolveMaterials;
        }
    }

    private void Update() {
        burnAmount += Time.deltaTime * burnSpeed;
        foreach (Renderer renderer in renderers) {
            Material[] materials = renderer.sharedMaterials;
            foreach (Material material in materials) {
                material.SetFloat("_BurnAmount", burnAmount);
            }
        }
        if (burnAmount >= 1f) {
            Destroy(gameObject);
        }
    }

    private void SetTexture(Material oldMaterial, Material newMaterial) { // 设置材质
        if (oldMaterial.HasTexture("_MainTex")) {
            Texture texture = oldMaterial.GetTexture("_MainTex");
            newMaterial.SetTexture("_MainTex", texture);
        }
    }

    private void SetColor(Material oldMaterial, Material newMaterial) { // 设置颜色
        Color color = Color.white;
        if (oldMaterial.HasColor("_Color")) {
            color = oldMaterial.GetColor("_Color");
        }
        newMaterial.SetColor("_Color", color);
    }
}

        运行效果如下。