Unity Shader Example 28 (Reuse Depth Buffer)

两个相机，同一个位置，渲染不同层次的物体，也可以有深度关系的一种做法。

1. 层次结构

SceneCamera 只渲染 除特效层以外的 物体，(特效层 cameraEffect)

EffectCamera 只渲染 特效层 的物体，

2. SceneCamera 的设置：

Culling Mask ： 去除 特效层次，cameraEffect

添加RenderTexture : EffectTexture

添加SceneCameraRTMgr ： 为了把 EffectTexture的颜色变成黑色，但是会保存 depth Buffer.

脚本：

using System.Collections;using System.Collections.Generic;using UnityEngine;public class SceneCamerRTMgr : MonoBehaviour {    public Shader delMainColShader;    private Material _delMainColMat;    void Start()    {        _delMainColMat = new Material(delMainColShader);    }    public void OnRenderImage(RenderTexture source, RenderTexture destination)    {        Graphics.Blit(source, destination, _delMainColMat);    }}

Shader:

Shader "Hidden/DelMainCol"{Properties{_MainTex ("Texture", 2D) = "white" {}}SubShader{// No culling or depthCull Off ZWrite Off ZTest AlwaysPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert (appdata v){v2f o;o.vertex = UnityObjectToClipPos(v.vertex);o.uv = v.uv;return o;}sampler2D _MainTex;fixed4 frag (v2f i) : SV_Target{return fixed4(0, 0, 0, 0);}ENDCG}}}

目的只渲染场景的物体。

3. EffectCamera 的设置：

Culling Mask ： cameraEffect ,(为了只渲染特效)

Clear Flags : Dont Clear. (因为EffectTexture被清空了颜色，这里就是为了不清空 EffectTexture的深度信息，可以让 EffectCamera 渲染的时候，利用 EffectTexture的深度缓存)

最后的结果就是， EffectCamera 利用 EffectTexture 的深度缓存来渲染，这样就可以进行深度测试。

4. Main Camera:

Culling Mask : 去掉CameraEffect, 不渲染特效。

脚本：

using System.Collections;using System.Collections.Generic;using UnityEngine;public class EffectBloom : MonoBehaviour {    public RenderTexture effectBloomRT;    public Shader blendFactorShader;    private Material _blendFactorMat;    public Shader bloomEffectShader;    private Material _bloomEffectMat;    private void Start()    {        _blendFactorMat = new Material(blendFactorShader);        _bloomEffectMat = new Material(bloomEffectShader);    }    public void OnRenderImage(RenderTexture source, RenderTexture destination)    {        RenderTexture tempBlendFactorRT = RenderTexture.GetTemporary(source.width, source.height, 0, source.format);        Graphics.Blit(effectBloomRT, tempBlendFactorRT, _blendFactorMat);        _bloomEffectMat.SetTexture("_BlendFactorTex", tempBlendFactorRT);        _bloomEffectMat.SetTexture("_EffectBloomTex", effectBloomRT);        Graphics.Blit(source, destination, _bloomEffectMat);        RenderTexture.ReleaseTemporary(tempBlendFactorRT);    }}

Shader :

Shader "Hidden/BlendFactor"{Properties{_MainTex("_MainTex", 2D) = "white" {}}SubShader{// No culling or depthCull Off ZWrite Off ZTest AlwaysPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert (appdata v){v2f o;o.vertex = UnityObjectToClipPos(v.vertex);o.uv = v.uv;return o;}sampler2D _MainTex;fixed4 frag (v2f i) : SV_Target{fixed4 col = tex2D(_MainTex, i.uv);return fixed4(col.a, 0, 0, 1);}ENDCG}}}

Shader "Hidden/BloomEffect"{Properties{_MainTex ("Texture", 2D) = "white" {}_BlendFactorTex("Blend Factor Textrue", 2D) = "white" {}_EffectBloomTex("Effect Bloom Textrue", 2D) = "white" {}}SubShader{// No culling or depthCull Off ZWrite Off ZTest AlwaysPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert (appdata v){v2f o;o.vertex = UnityObjectToClipPos(v.vertex);o.uv = v.uv;return o;}sampler2D _MainTex;sampler2D _BlendFactorTex;sampler2D _EffectBloomTex;fixed4 frag (v2f i) : SV_Target{fixed4 mainCol = tex2D(_MainTex, i.uv);fixed4 effectCol = tex2D(_EffectBloomTex, i.uv);fixed4 blendFactorCol = tex2D(_BlendFactorTex, i.uv);fixed factor = blendFactorCol.r;//fixed factor = (effectCol.r + effectCol.g + effectCol.b) * 0.333333;//fixed4 resCol = lerp(mainCol, effectCol, factor);fixed4 resCol = 3 * effectCol * factor + mainCol;return resCol;}ENDCG}}}