制作镜面反射脚本

这里面我转一个镜面反射，再阐述一些遇到的问题，先建立以个Shader，名字可以叫做MirrorReflection，脚本如下：

Shader "FX/Mirror Reflection"{Properties{_MainTex("Base(RGB)",2D)="white"{}  _ReflectionTex("Reflection",2D)="white"{TexGen ObjectLinear}}        // two texture cards: full thingSubshader{Pass         {SetTexture[_MainTex]{combine texture}   SetTexture[_ReflectionTex]{matrix [_ProjMatrix] combine texture*previous}  }}        // fallback: just main texture        Subshader{Pass  {SetTexture [_MainTex]{combine texture}  }        }}

在建立一个cs脚本，名字叫做MirrorReflection，脚本如下：

using UnityEngine;using System.Collections;//实际上 This is in fact just the Water script from Pro Standard Assets,// just with refraction stuff removed.[ExecuteInEditMode]// Make mirror live-update even when not in play modepublic class MirrorReflection:MonoBehaviour{public bool m_DisablePixelLights=true;public int m_TextureSize=256;        public float m_ClipPlaneOffset=0.07f;        public LayerMask m_ReflectLayers=-1;        private Hashtable m_ReflectionCameras=new Hashtable(); // Camera ->Camera table        private RenderTexture m_ReflectionTexture=null;        private int m_OldReflectionTextureSize=0;        private static bool s_InsideRendering=false;                // This is called when it's known that the object will be rendered by some        // camera. We render reflections and do other updates here.        // Because the script executes in edit mode,reflections for the scene view        // camera will just work!        public void OnWillRenderObject()        {if(!enabled || !renderer || !renderer.sharedMaterial || !renderer.enabled )return;                Camera cam=Camera.current;                if(!cam )return;                                // Safeguard from recursive reflections.                 if(s_InsideRendering )return;                                s_InsideRendering=true;                                Camera reflectionCamera;                                CreateMirrorObjects(cam,out reflectionCamera );                                // find out the reflection plane:position and normal in world space                Vector3 pos=transform.position;                Vector3 normal=transform.up;                                // Optionally disable pixel lights for reflection                int oldPixelLightCount=QualitySettings.pixelLightCount;                if(m_DisablePixelLights )QualitySettings.pixelLightCount=0;                                UpdateCameraModes(cam,reflectionCamera );                                // Render reflection                // Reflect camera around reflection plane                float d=-Vector3.Dot(normal,pos)-m_ClipPlaneOffset;                                Vector4 reflectionPlane=new Vector4(normal.x,normal.y,normal.z,d);                                Matrix4x4 reflection=Matrix4x4.zero;                                CalculateReflectionMatrix(ref reflection,reflectionPlane);Vector3 oldpos=cam.transform.position;Vector3 newpos=reflection.MultiplyPoint(oldpos );reflectionCamera.worldToCameraMatrix=cam.worldToCameraMatrix * reflection;// Setup oblique projection matrix so that near plane is our reflection// plane. This way we clip everything below/above it for free.Vector4 clipPlane=CameraSpacePlane(reflectionCamera,pos,normal,1.0f );Matrix4x4 projection=cam.projectionMatrix;CalculateObliqueMatrix(ref projection,clipPlane);reflectionCamera.projectionMatrix=projection;reflectionCamera.cullingMask=~(1<<4)& m_ReflectLayers.value; // never render water layerreflectionCamera.targetTexture=m_ReflectionTexture;GL.SetRevertBackfacing(true);reflectionCamera.transform.position=newpos;Vector3 euler=cam.transform.eulerAngles;reflectionCamera.transform.eulerAngles=new Vector3(0,euler.y,euler.z);reflectionCamera.Render();reflectionCamera.transform.position=oldpos;GL.SetRevertBackfacing(false);Material[]materials=renderer.sharedMaterials;foreach(Material mat in materials ){if(mat.HasProperty("_ReflectionTex"))mat.SetTexture("_ReflectionTex",m_ReflectionTexture );}// Set matrix on the shader that transforms UVs from object space into screen// space. We want to just project reflection texture on screen.Matrix4x4 scaleOffset=Matrix4x4.TRS(new Vector3(0.5f,0.5f,0.5f),Quaternion.identity,new Vector3(0.5f,0.5f,0.5f));Vector3 scale=transform.lossyScale;Matrix4x4 mtx=transform.localToWorldMatrix * Matrix4x4.Scale(new Vector3(1.0f/scale.x,1.0f/scale.y,1.0f/scale.z));mtx=scaleOffset * cam.projectionMatrix * cam.worldToCameraMatrix * mtx;foreach(Material mat in materials ){mat.SetMatrix("_ProjMatrix",mtx );}// Restore pixel light countif(m_DisablePixelLights )QualitySettings.pixelLightCount=oldPixelLightCount;s_InsideRendering=false;}// Cleanup all the objects we possibly have createdvoid OnDisable(){if(m_ReflectionTexture ){DestroyImmediate(m_ReflectionTexture );m_ReflectionTexture=null;}foreach(DictionaryEntry kvp in m_ReflectionCameras )DestroyImmediate(((Camera)kvp.Value).gameObject );m_ReflectionCameras.Clear();}private void UpdateCameraModes(Camera src,Camera dest ){if(dest==null )return;// set camera to clear the same way as current cameradest.clearFlags=src.clearFlags;dest.backgroundColor=src.backgroundColor; if(src.clearFlags==CameraClearFlags.Skybox ){Skybox sky=src.GetComponent(typeof(Skybox))as Skybox;Skybox mysky=dest.GetComponent(typeof(Skybox))as Skybox;if(!sky || !sky.material ){mysky.enabled=false;}else{mysky.enabled=true;mysky.material=sky.material;}}// update other values to match current camera.// even if we are supplying custom camera&projection matrices,// some of values are used elsewhere(e.g. skybox uses far plane)dest.farClipPlane=src.farClipPlane;dest.nearClipPlane=src.nearClipPlane;dest.orthographic=src.orthographic;dest.fieldOfView=src.fieldOfView;dest.aspect=src.aspect;dest.orthographicSize=src.orthographicSize;}// On-demand create any objects we needprivate void CreateMirrorObjects(Camera currentCamera,out Camera reflectionCamera ){reflectionCamera=null;// Reflection render textureif(!m_ReflectionTexture || m_OldReflectionTextureSize !=m_TextureSize ){if(m_ReflectionTexture )DestroyImmediate(m_ReflectionTexture );m_ReflectionTexture=new RenderTexture(m_TextureSize,m_TextureSize,16 );m_ReflectionTexture.name="__MirrorReflection" + GetInstanceID();m_ReflectionTexture.isPowerOfTwo=true;m_ReflectionTexture.hideFlags=HideFlags.DontSave;m_OldReflectionTextureSize=m_TextureSize;}// Camera for reflectionreflectionCamera=m_ReflectionCameras[currentCamera]as Camera;if(!reflectionCamera )// catch both not-in-dictionary and in-dictionary-but-deleted-GO{GameObject go=new GameObject("Mirror Refl Camera id" + GetInstanceID()+ " for " + currentCamera.GetInstanceID(),typeof(Camera),typeof(Skybox));reflectionCamera=go.camera;reflectionCamera.enabled=false;reflectionCamera.transform.position=transform.position;reflectionCamera.transform.rotation=transform.rotation;reflectionCamera.gameObject.AddComponent("FlareLayer");go.hideFlags=HideFlags.HideAndDontSave;m_ReflectionCameras[currentCamera]=reflectionCamera;} }// Extended sign:returns -1,0 or 1 based on sign of aprivate static float sgn(float a){if(a>0.0f)return 1.0f;        if(a<0.0f)return -1.0f;        return 0.0f;}// Given position/normal of the plane,calculates plane in camera space.private Vector4 CameraSpacePlane(Camera cam,Vector3 pos,Vector3 normal,float sideSign){Vector3 offsetPos=pos + normal * m_ClipPlaneOffset;Matrix4x4 m=cam.worldToCameraMatrix;Vector3 cpos=m.MultiplyPoint(offsetPos );Vector3 cnormal=m.MultiplyVector(normal ).normalized * sideSign;return new Vector4(cnormal.x,cnormal.y,cnormal.z,-Vector3.Dot(cpos,cnormal));}//调整给定的射影矩阵以便最近的平面Adjusts the given projection matrix so that near plane is the given clipPlane// clipPlane is given in camera space. See article in Game Programming Gems 5.private static void CalculateObliqueMatrix(ref Matrix4x4 projection,Vector4 clipPlane){Vector4 q=projection.inverse * new Vector4(sgn(clipPlane.x),sgn(clipPlane.y),1.0f,1.0f);        Vector4 c=clipPlane *(2.0F /(Vector4.Dot(clipPlane,q)));        // third row=clip plane -fourth row        projection[2]=c.x -projection[3];        projection[6]=c.y -projection[7];        projection[10]=c.z -projection[11];        projection[14]=c.w -projection[15];}//围绕给定的平面计算折射矩阵private static void CalculateReflectionMatrix(ref Matrix4x4 reflectionMat,Vector4 plane){reflectionMat.m00=(1F -2F*plane[0]*plane[0]);        reflectionMat.m01=(-2F*plane[0]*plane[1]);        reflectionMat.m02=(-2F*plane[0]*plane[2]);        reflectionMat.m03=(-2F*plane[3]*plane[0]);                reflectionMat.m10=(-2F*plane[1]*plane[0]);        reflectionMat.m11=(1F -2F*plane[1]*plane[1]);        reflectionMat.m12=(-2F*plane[1]*plane[2]);        reflectionMat.m13=(-2F*plane[3]*plane[1]);                reflectionMat.m20=(-2F*plane[2]*plane[0]);        reflectionMat.m21=(-2F*plane[2]*plane[1]);        reflectionMat.m22=(1F -2F*plane[2]*plane[2]);        reflectionMat.m23=(-2F*plane[3]*plane[2]);                reflectionMat.m30=0F;        reflectionMat.m31=0F;        reflectionMat.m32=0F;        reflectionMat.m33=1F;        }}

值得注意的是，地面，或者镜面尽量用U3d里面自建的plane,把shader和cs脚本直接赋予到该plane上就出效果了。其他物体不必赋予。