镜面反射——地面反射

Paste_Image.png

using UnityEngine;

using System.Collections;

[ExecuteInEditMode]
public class Mirror : MonoBehaviour
{
public bool m_DisablePixelLights = true;
public int m_TextureSize = 256;
public float m_ClipPlaneOffset = 0.07f;
public bool m_IsFlatMirror = true;

public LayerMask m_ReflectLayers = -1;
   
private Hashtable m_ReflectionCameras = new Hashtable(); 

private RenderTexture m_ReflectionTexture = null;
private int m_OldReflectionTextureSize = 0;

private static bool s_InsideRendering = false;

public void OnWillRenderObject()
{
    if( !enabled || !GetComponent() || !GetComponent().sharedMaterial || !GetComponent().enabled )
        return;
       
    Camera cam = Camera.current;
    if( !cam )
        return;

    if( s_InsideRendering )
        return;
    s_InsideRendering = true;
   
    Camera reflectionCamera;
    CreateMirrorObjects( cam, out reflectionCamera );
   
    Vector3 pos = transform.position;
    Vector3 normal;
    if(m_IsFlatMirror){
        normal = transform.up;
    }
    else{ 
        normal= transform.position - cam.transform.position ;
        normal.Normalize();
    }
    int oldPixelLightCount = QualitySettings.pixelLightCount;
    if( m_DisablePixelLights )
        QualitySettings.pixelLightCount = 0;
   
    UpdateCameraModes( cam, reflectionCamera );

    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;


    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; 
    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 = GetComponent().sharedMaterials;
    foreach( Material mat in materials ) {
        if( mat.HasProperty("_Ref") )
            mat.SetTexture( "_Ref", m_ReflectionTexture );
    }
    if( m_DisablePixelLights )
        QualitySettings.pixelLightCount = oldPixelLightCount;
   
    s_InsideRendering = false;
}

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;

    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;
        }
    }

    dest.farClipPlane = src.farClipPlane;
    dest.nearClipPlane = src.nearClipPlane;
    dest.orthographic = src.orthographic;
    dest.fieldOfView = src.fieldOfView;
    dest.aspect = src.aspect;
    dest.orthographicSize = src.orthographicSize;
    dest.renderingPath = src.renderingPath;
}


private void CreateMirrorObjects( Camera currentCamera, out Camera reflectionCamera )
{
    reflectionCamera = null;
   

    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;
    }
   

    reflectionCamera = m_ReflectionCameras[currentCamera] as Camera;
    if( !reflectionCamera ) 
    {
        GameObject go = new GameObject( "Mirror Refl Camera id" + GetInstanceID() + " for " + currentCamera.GetInstanceID(), typeof(Camera), typeof(Skybox) );
        reflectionCamera = go.GetComponent();
        reflectionCamera.enabled = false;
        reflectionCamera.transform.position = transform.position;
        reflectionCamera.transform.rotation = transform.rotation;
        reflectionCamera.gameObject.AddComponent();
        go.hideFlags = HideFlags.HideAndDontSave;
        m_ReflectionCameras[currentCamera] = reflectionCamera;
    }       
}

private static float sgn(float a)
{
    if (a > 0.0f) return 1.0f;
    if (a < 0.0f) return -1.0f;
    return 0.0f;
}

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) );
}

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)));

    projection[2] = c.x - projection[3];
    projection[6] = c.y - projection[7];
    projection[10] = c.z - projection[11];
    projection[14] = c.w - projection[15];
}

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;
}

}