[Unity3D]Shader编程之动态屏幕遮罩

转载 https://blog.csdn.net/u012741077/article/details/78425834

屏幕可视范围跟随目标物体移动，可修改可视范围大小，边缘渐变大小、以及遮罩颜色，支持最高物体数量可在Shader中修改，当前版本支持最多9个物体。

效果图如下：

控制面板如下：

Shader代码如下：

Shader "Peter/DarkEffect"{ Properties { _MainTex ("Texture", 2D) = "white" {} }

SubShader { // No culling or depth Cull Off ZWrite Off ZTest Always

Pass { CGPROGRAM #pragma vertex vert #pragma fragment frag

#include "UnityCG.cginc"

//追踪物体最多个数 #define ItemSize 9

struct appdata { float4 vertex : POSITION; float2 uv : TEXCOORD0; };

struct v2f { float2 uv : TEXCOORD0; float4 vertex : SV_POSITION; };

sampler2D _MainTex;

fixed4 _DarkColor; float _SmoothLength; fixed _ItemCnt; float4 _Item[ItemSize];

v2f vert (appdata v) { v2f o; o.vertex = UnityObjectToClipPos(v.vertex); o.uv = v.uv; return o; }

fixed CalcAlpha(float4 vt, float4 pt) { if(pt.z < 0) { return 1; }

float distPow2 = pow(vt.x - pt.x, 2) + pow(vt.y - pt.y, 2); float dist = (distPow2 > 0) ? sqrt(distPow2) : 0;

float smoothLength = _SmoothLength; if(smoothLength < 0) { smoothLength = 0; }

float maxValue = pt.z; float minValue = pt.z - smoothLength; if(minValue < 0) { minValue = 0; smoothLength = pt.z; }

if(dist <= minValue) { return 0; } else if (dist > maxValue) { return 1; }

fixed retVal = (dist - minValue) / smoothLength;

return retVal; }

fixed4 frag (v2f i) : SV_Target { fixed alphaVal = 1; fixed tmpVal = 1;

for(fixed index = 0; index < _ItemCnt; ++index) { tmpVal = CalcAlpha(i.vertex, _Item[index]); if(tmpVal < alphaVal) { alphaVal = tmpVal; } }

alphaVal *= _DarkColor.a;

return tex2D(_MainTex, i.uv) * ( 1 - alphaVal) + _DarkColor * alphaVal; }

ENDCG } }}C#调用代码如下：

using System.Collections;using System.Collections.Generic;using UnityEngine;

[ExecuteInEditMode][RequireComponent(typeof(Camera))]public class DarkEffect : MonoBehaviour{ [System.Serializable] public class Item { [SerializeField] public Transform target;

[SerializeField] public int radius;

public Vector3 GetScreenPosition(Camera cam) { return cam.WorldToScreenPoint(target.position); } }

//渐变像素数量 public int _smoothLength = 20; //遮罩混合颜色 public Color _darkColor = Color.black; //目标物体 public List _items = new List();

protected Material _mainMaterial; protected Camera _mainCamera;

Vector4[] _itemDatas; Item _tmpItem; Vector4 _tmpVt; Vector3 _tmpPos; int _tmpScreenHeight;

private void OnEnable() { _mainMaterial = new Material(Shader.Find("Peter/DarkEffect")); _mainCamera = GetComponent(); }

private void OnRenderImage(RenderTexture source, RenderTexture destination) {

if (_itemDatas == null || _itemDatas.Length != _items.Count) { _itemDatas = new Vector4[_items.Count]; }

_tmpScreenHeight = Screen.height;

for (int i = 0; i < _items.Count; i++) { _tmpItem = _items[i]; _tmpPos = _tmpItem.GetScreenPosition(_mainCamera);

_tmpVt.x = _tmpPos.x; _tmpVt.y = _tmpScreenHeight - _tmpPos.y; _tmpVt.z = _tmpItem.radius; _tmpVt.w = 0;

_itemDatas[i] = _tmpVt; }

_mainMaterial.SetInt("_SmoothLength", _smoothLength); _mainMaterial.SetColor("_DarkColor", _darkColor); _mainMaterial.SetInt("_ItemCnt", _itemDatas.Length); _mainMaterial.SetVectorArray("_Item", _itemDatas);

Graphics.Blit(source, destination, _mainMaterial); }}

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