Unity3D--镜面反射

首先，新建一个Shader：

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 textureSubshader {Pass {SetTexture [_MainTex] { combine texture }}}}

 

第二，新建一个脚本MirrorReflection.cs:

注意：被赋予脚本的物体不能缩放也就是物体的Rransform.scale的值均为1。

using UnityEngine;using System.Collections;// 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 tableprivate 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 spaceVector3 pos = transform.position;Vector3 normal = transform.up;// Optionally disable pixel lights for reflectionint oldPixelLightCount = QualitySettings.pixelLightCount;if (m_DisablePixelLights)QualitySettings.pixelLightCount = 0;UpdateCameraModes(cam, reflectionCamera);// Render reflection// Reflect camera around reflection planefloat 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));}// 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 rowprojection[2] = c.x – projection[3];projection[6] = c.y – projection[7];projection[10] = c.z – projection[11];projection[14] = c.w – projection[15];}// Calculates reflection matrix around the given planeprivate 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;}}