Unity3D一个镜面反射的材质
Shader：
Shader "FX/Mirror Reflection" {
Properties {
_MainTex ("Base (RGB)", 2D) = "white" {}
_ReflectionTex ("Reflection", 2D) = "white" { TexGen ObjectLinear }
}
// two texture cards: full thing
Subshader {
Pass {
SetTexture[_MainTex] { combine texture }
SetTexture[_ReflectionTex] { matrix [_ProjMatrix] combine texture * previous }
}
}
// fallback: just main texture
Subshader {
Pass {
SetTexture [_MainTex] { combine texture }
}
}
}C#
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 mode
public 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 layer
reflectionCamera.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 count
if( m_DisablePixelLights )
QualitySettings.pixelLightCount = oldPixelLightCount;
s_InsideRendering = false;
}
// Cleanup all the objects we possibly have created
void 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 camera
dest.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 need
private void CreateMirrorObjects( Camera currentCamera, out Camera reflectionCamera )
{
reflectionCamera = null;
// Reflection render texture
if( !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 reflection
reflectionCamera = 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 a
private 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 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];
}
// Calculates reflection matrix around the given plane
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;
}
}
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