Unity Shader 屏幕后处理之血屏

欢迎来到我的第一篇博客

看了冯乐乐老师的《Unity Shader入门精要》在感叹Shader牛逼的同时也对图形学产生了莫大的兴趣，推荐各位在学Unity已及对Shader有兴趣的小伙伴一定要看看。因为很基础，所以代码没什么注释。

话不多说，直接上图：
我实现的是一个呼吸效果，只截了在变化中的图。

然后上代码：

public class BloodScreen : PostEffectsBase {
	
	//本代码是放在摄像机上的，而且继承了《Unity Shader入门精要》中的 PostEffectsBase类
    public Shader m_BloodScreenShader;
    private Material m_BloodScreenMaterial;
    bool down = false;

    public Material material
    {
        get
        {
            return m_BloodScreenMaterial=
                CheckShaderAndCreateMaterial
                (m_BloodScreenShader,m_BloodScreenMaterial);
        }
    }
    public Texture2D m_BloodTexture;

    [Range(0.0f, 1.0f)]
    public float m_Alpha=0.5f;

    void OnRenderImage(RenderTexture src,RenderTexture dest)
    {
        if (material!=null&&m_BloodTexture!=null)
        {
        	//实现呼吸效果的判断，写得不太好
	        if (!down)
	        {
	            m_Alpha += Time.deltaTime;
	            if (m_Alpha >= 1.0) down = true;
	        }
	        else
	        {
	            m_Alpha -= Time.deltaTime;
	            if (m_Alpha <= 0) down = false;
	        }
            material.SetTexture("_BloodTex", m_BloodTexture);
            material.SetFloat("_Alpha", m_Alpha);
            Graphics.Blit(src, dest,material);
            
        }
        else
        {
            Graphics.Blit(src, dest);
        }
    }
}

PostEffectsBase类，怕大家找不着我就直接放上来吧
因为是我自己照着写的所以没有注释，如果看过书的小伙伴一定知道作用

using UnityEngine;
using System.Collections;

[ExecuteInEditMode]
[RequireComponent (typeof(Camera))]
public class PostEffectsBase : MonoBehaviour {

	// Called when start
	protected void CheckResources() {
		bool isSupported = CheckSupport();
		
		if (isSupported == false) {
			NotSupported();
		}
	}

	// Called in CheckResources to check support on this platform
	protected bool CheckSupport() {
		if (SystemInfo.supportsImageEffects == false) {
			Debug.LogWarning("This platform does not support image effects or render textures.");
			return false;
		}
		
		return true;
	}

	// Called when the platform doesn't support this effect
	protected void NotSupported() {
		enabled = false;
	}
	
	protected void Start() {
		CheckResources();
	}

	// Called when need to create the material used by this effect
	protected Material CheckShaderAndCreateMaterial(Shader shader, Material material) {
		if (shader == null) {
			return null;
		}
		
		if (shader.isSupported && material && material.shader == shader)
			return material;
		
		if (!shader.isSupported) {
			return null;
		}
		else {
			material = new Material(shader);
			material.hideFlags = HideFlags.DontSave;
			if (material)
				return material;
			else 
				return null;
		}
	}

接下来是Shader的代码，非常简单的代码，起最大作用的是后面的混合模式。
有关混合模式，链接: link.

Shader "Learn/BloodScreen"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_BloodTex ("Blood Texture", 2D) = "white" {}
		_Alpha("Alpha",Range(0.0,1.0))=0.5
	}
	SubShader
	{
		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#include "UnityCG.cginc"

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

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

			sampler2D _MainTex;
			float4 _MainTex_ST;
			sampler2D _BloodTex;
			float4 _BloodTex_ST;
			fixed _Alpha;
			
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv.xy = TRANSFORM_TEX(v.uv, _MainTex);
				o.uv.zw = TRANSFORM_TEX(v.uv, _BloodTex);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				fixed4 base = tex2D(_MainTex, i.uv.xy);
				fixed4 blood=tex2D(_BloodTex,i.uv.zw);
				blood*=_Alpha;
				fixed4 col=base*blood+base*(1-_Alpha);//手动混合模式
				return col;
			}
			ENDCG
		}
	}
}

差点忘了，图片，可以在爱给网下载http://www.aigei.com/s?q=%E8%A1%80%E6%B6%B2&type=game&page=2

好了，我的第一篇博客到此结束，有不对的地方欢迎指正，感谢！