第十三章 使用深度纹理全局雾

PostEffectsBase.cs

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 || SystemInfo.supportsRenderTextures == 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;
        }
    }
}

FogWithDepthTexture.cs

using UnityEngine;
using System.Collections;

public class FogWithDepthTexture : PostEffectsBase {

    public Shader fogShader;
    private Material fogMaterial = null;

    public Material material {  
        get {
            fogMaterial = CheckShaderAndCreateMaterial(fogShader, fogMaterial);
            return fogMaterial;
        }  
    }

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

    private Transform myCameraTransform;
    public Transform cameraTransform {
        get {
            if (myCameraTransform == null) {
                myCameraTransform = camera.transform;
            }

            return myCameraTransform;
        }
    }

    [Range(0.0f, 3.0f)]
    public float fogDensity = 1.0f;

    public Color fogColor = Color.white;

    public float fogStart = 0.0f;
    public float fogEnd = 2.0f;

    void OnEnable() {
        camera.depthTextureMode |= DepthTextureMode.Depth;
    }
    
    void OnRenderImage (RenderTexture src, RenderTexture dest) {
        if (material != null) {
            Matrix4x4 frustumCorners = Matrix4x4.identity;

            float fov = camera.fieldOfView;
            float near = camera.nearClipPlane;
            float aspect = camera.aspect;

            float halfHeight = near * Mathf.Tan(fov * 0.5f * Mathf.Deg2Rad);
            Vector3 toRight = cameraTransform.right * halfHeight * aspect;
            Vector3 toTop = cameraTransform.up * halfHeight;

            Vector3 topLeft = cameraTransform.forward * near + toTop - toRight;
            float scale = topLeft.magnitude / near;

            topLeft.Normalize();
            topLeft *= scale;

            Vector3 topRight = cameraTransform.forward * near + toRight + toTop;
            topRight.Normalize();
            topRight *= scale;

            Vector3 bottomLeft = cameraTransform.forward * near - toTop - toRight;
            bottomLeft.Normalize();
            bottomLeft *= scale;

            Vector3 bottomRight = cameraTransform.forward * near + toRight - toTop;
            bottomRight.Normalize();
            bottomRight *= scale;

            frustumCorners.SetRow(0, bottomLeft);
            frustumCorners.SetRow(1, bottomRight);
            frustumCorners.SetRow(2, topRight);
            frustumCorners.SetRow(3, topLeft);

            material.SetMatrix("_FrustumCornersRay", frustumCorners);

            material.SetFloat("_FogDensity", fogDensity);
            material.SetColor("_FogColor", fogColor);
            material.SetFloat("_FogStart", fogStart);
            material.SetFloat("_FogEnd", fogEnd);

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

内置渲染管线

Shader "SunY/C13-FogWithDepthTexture"
{
    Properties
    {
        _MainTex("Maint Tex", 2D) = "white"{}
        _FogDensity("Fog Density", float) = 1
        _FogColor("Fog Color", Color) = (1, 1, 1, 1)
        _FogStart("Fog Start", float) = 0
        _FogEnd("Fog End", float) = 1
    }

    SubShader
    {
        CGINCLUDE

        #include "UnityCG.cginc"

        float4x4 _FrustumCornersRay;

        sampler2D _MainTex;
        half4 _MainTex_TexelSize;
        sampler2D _CameraDepthTexture;
        float _FogDensity;
        fixed4 _FogColor;
        float _FogStart;
        float _FogEnd;

        struct v2f
        {
            float4 pos : SV_POSITION;
            half2 uv : TEXCOORD0;
            half2 uv_depth : TEXCOORD1;
            float4 interpolatedRay : TEXCOORD2;
        };

        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

            int index = 0;
            if(v.texcoord.x < 0.5 && v.texcoord.y < 0.5)
            {
                index = 0;
            }
            else if(v.texcoord.x > 0.5 && v.texcoord.y < 0.5)
            {
                index = 1;
            }
            else if(v.texcoord.x > 0.5 && v.texcoord.y > 0.5)
            {
                index = 2;
            }
            else
            {
                index = 3;
            }

            #if UNITY_UV_STARTS_AT_TOP
                if(_MainTex_TexelSize.y < 0)
                    index = 3 - index;
            #endif

            o.interpolatedRay = _FrustumCornersRay[index];

            return o;
        }

        fixed4 frag(v2f i) : SV_Target
        {
            float linearDepth = LinearEyeDepth(SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, i.uv_depth));
            float3 worldPos = _WorldSpaceCameraPos + linearDepth * i.interpolatedRay.xyz;

            float fogDensity = (_FogEnd - worldPos.y) / (_FogEnd - _FogStart);
            fogDensity = saturate(fogDensity * _FogDensity);

            fixed4 finalColor = tex2D(_MainTex, i.uv);
            finalColor.rgb = lerp(finalColor.rgb, _FogColor.rgb, fogDensity);

            return finalColor;
        }

        ENDCG

        Pass
        {
            ZTest Always
            ZWrite Off
            Cull Off

            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag

            ENDCG
        }
    }

    FallBack Off
}