Unity Shader 屏幕后处理 运动模糊 速度映射图

代码

using UnityEngine;

public class MotionBlurWithDepthTexture : PostEffectsBase
{

    public Shader motionBlurShader;
    private Material motionBlurMaterial = null;

    public Material material
    {
        get
        {
            motionBlurMaterial = CheckShaderAndCreateMaterial(motionBlurShader, motionBlurMaterial);
            return motionBlurMaterial;
        }
    }

    private Camera myCamera;
    public Camera camera
    {
        get
        {
            if (myCamera == null)
            {
                myCamera = GetComponent();
            }
            return myCamera;
        }
    }

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

    private Matrix4x4 previousViewProjectionMatrix;

    void OnEnable()
    {
        camera.depthTextureMode |= DepthTextureMode.Depth;

        previousViewProjectionMatrix = camera.projectionMatrix * camera.worldToCameraMatrix;
    }

    void OnRenderImage(RenderTexture src, RenderTexture dest)
    {
        if (material != null)
        {
            material.SetFloat("_BlurSize", blurSize);

            material.SetMatrix("_PreviousViewProjectionMatrix", previousViewProjectionMatrix);
            Matrix4x4 currentViewProjectionMatrix = camera.projectionMatrix * camera.worldToCameraMatrix;
            Matrix4x4 currentViewProjectionInverseMatrix = currentViewProjectionMatrix.inverse;
            material.SetMatrix("_CurrentViewProjectionInverseMatrix", currentViewProjectionInverseMatrix);
            previousViewProjectionMatrix = currentViewProjectionMatrix;

            Graphics.Blit(src, dest, material);
        }
        else
        {
            Graphics.Blit(src, dest);
        }
    }
}

shader

Shader "MyShader/MotionBlurWithDepthTexture"
{
    Properties
    {
        _MainTex("Base (RGB)", 2D) = "white" {}
        _BlurSize("Blur Size", Float) = 1.0
    }
        SubShader
        {
            CGINCLUDE

            #include "UnityCG.cginc"

            sampler2D _MainTex;
            half4 _MainTex_TexelSize;
            sampler2D _CameraDepthTexture;
            float4x4 _CurrentViewProjectionInverseMatrix;
            float4x4 _PreviousViewProjectionMatrix;
            half _BlurSize;

            struct v2f
            {
                float4 pos : SV_POSITION;
                half2 uv : TEXCOORD0;
                half2 uv_depth : TEXCOORD1;
            };

            v2f vert(appdata_img v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);

                o.uv = v.texcoord;
                o.uv_depth = v.texcoord;

                #if UNITY_UV_STARTS_AT_TOP
                if (_MainTex_TexelSize.y < 0)
                    o.uv_depth.y = 1 - o.uv_depth.y;
                #endif

                return o;
            }

            fixed4 frag(v2f i) : SV_Target
            {
                // Get the depth buffer value at this pixel.
                float d = SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, i.uv_depth);
            // H is the viewport position at this pixel in the range -1 to 1.
            float4 H = float4(i.uv.x * 2 - 1, i.uv.y * 2 - 1, d * 2 - 1, 1);
            // Transform by the view-projection inverse.
            float4 D = mul(_CurrentViewProjectionInverseMatrix, H);
            // Divide by w to get the world position. 
            float4 worldPos = D / D.w;

            // Current viewport position 
            float4 currentPos = H;
            // Use the world position, and transform by the previous view-projection matrix.  
            float4 previousPos = mul(_PreviousViewProjectionMatrix, worldPos);
            // Convert to nonhomogeneous points [-1,1] by dividing by w.
            previousPos /= previousPos.w;

            // Use this frame's position and last frame's to compute the pixel velocity.
            float2 velocity = (currentPos.xy - previousPos.xy) / 2.0f;

            float2 uv = i.uv;
            float4 c = tex2D(_MainTex, uv);
            uv += velocity * _BlurSize;
            for (int it = 1; it < 3; it++, uv += velocity * _BlurSize) {
                float4 currentColor = tex2D(_MainTex, uv);
                c += currentColor;
            }
            c /= 3;

            return fixed4(c.rgb, 1.0);
        }

        ENDCG

        Pass
            {
            ZTest Always Cull Off ZWrite Off

            CGPROGRAM

            #pragma vertex vert  
            #pragma fragment frag  

            ENDCG
        }
        }
            FallBack Off
}

适用于场景静止，摄像机快速运动

参考 我买的 untiy shader 入门精要