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EDIT 1: So it seems this is a common issue with Unity, and it comes from a bug in which custom camera matrices break deferred lighting and shadows. This topic right here talks about it a bit, but the solution they provide doesn't seem to work in my case. So now I need to figure out why Unity does this, and if I can't fix it, figure out how I can get the lights/shadows on to the render texture I display.

I've been using the script below to render a portal effect, all it is is a modified version of Unity's water.cs script.

Now this script works in forward rendering, but for some reason when I turn the rendering path to deferred it doesn't render any lights or shadows on the rendertexture (I've tested it, the error is happening in the render texture this script produces.)

I've been scouring through the script, and testing every section, but I can't seem to find why it wouldn't be rendering lights or shadows to the render texture it outputs.

I'm going to continue researching and looking through the script, it seems the problem is due to the custom projection matrix I make for the camera.

This is the area that is causing the problem:

            // Render reflection
            // Reflect camera around reflection plane            
            Vector4     reflectionPlaneUp   = new Vector4 (normal.x, normal.y, normal.z, - m_ClipPlaneOffset);
            Vector4     reflectionPlaneRt   = new Vector4 (right.x,  right.y,  right.z,  0);

            Matrix4x4   reflectionUp        = Matrix4x4.zero;
            Matrix4x4   reflectionRt        = Matrix4x4.zero;
            Matrix4x4   reflectionSum       = Matrix4x4.zero;          
            Quaternion  rotate              = transform.rotation * Quaternion.Inverse(SecondPortal.transform.rotation);

            CalculateReflectionMatrix(ref reflectionUp, reflectionPlaneUp);
            CalculateReflectionMatrix(ref reflectionRt, reflectionPlaneRt); 

            //Step1 Move to BEGIN OF COORDINATES  
            reflectionSum = Matrix4x4.TRS(transform.position, Quaternion.identity, new Vector3(1,1,1)); 
            //Step2 reflect from Normal and Right vectors
            reflectionSum *= reflectionUp * reflectionRt;  
            //Step3 Rotate Camera on Difference Quaternion between 2 portals
            reflectionSum *= Matrix4x4.TRS(new Vector3(0,0,0), rotate, new Vector3(1,1,1));
            //Step4 Move to Other portal position         
            reflectionSum *= Matrix4x4.TRS(-SecondPortal.transform.position, Quaternion.identity, new Vector3(1,1,1));

            //Apply all transformations on Portal camera    
            reflectionCamera.worldToCameraMatrix = cam.worldToCameraMatrix * reflectionSum;

            // 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, SecondPortal.transform.position, SecondPortal.transform.up, 1.0f );
            Matrix4x4 projection = cam.projectionMatrix;
            CalculateObliqueMatrix (ref projection, clipPlane);
            reflectionCamera.projectionMatrix = projection;

And these are the functions you see it call in the snippet above:

// 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 and
    // http://aras-p.info/texts/obliqueortho.html
    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;
    }

Here's the full script:

    public bool m_DisablePixelLights = true;
    public int m_TextureSize = 256;
    public float m_ClipPlaneOffset = 0.01f;

    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;

    public Transform SecondPortal = null;

    // 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 normal  = transform.up;
        Vector3 right   = transform.right;
        // 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
        Vector4     reflectionPlaneUp   = new Vector4 (normal.x, normal.y, normal.z, - m_ClipPlaneOffset);
        Vector4     reflectionPlaneRt   = new Vector4 (right.x,  right.y,  right.z,  0);

        Matrix4x4   reflectionUp        = Matrix4x4.zero;
        Matrix4x4   reflectionRt        = Matrix4x4.zero;
        Matrix4x4   reflectionSum       = Matrix4x4.zero;          
        Quaternion  rotate              = transform.rotation * Quaternion.Inverse(SecondPortal.transform.rotation);

        CalculateReflectionMatrix(ref reflectionUp, reflectionPlaneUp);
        CalculateReflectionMatrix(ref reflectionRt, reflectionPlaneRt); 

        //Step1 Move to BEGIN OF COORDINATES  
        reflectionSum = Matrix4x4.TRS(transform.position, Quaternion.identity, new Vector3(1,1,1)); 
        //Step2 reflect from Normal and Right vectors
        reflectionSum *= reflectionUp * reflectionRt;  
        //Step3 Rotate Camera on Difference Quaternion between 2 portals
        reflectionSum *= Matrix4x4.TRS(new Vector3(0,0,0), rotate, new Vector3(1,1,1));
        //Step4 Move to Other portal position         
        reflectionSum *= Matrix4x4.TRS(-SecondPortal.transform.position, Quaternion.identity, new Vector3(1,1,1));

        //Apply all transformations on Portal camera    
        reflectionCamera.worldToCameraMatrix = cam.worldToCameraMatrix * reflectionSum;

        // 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, SecondPortal.transform.position, SecondPortal.transform.up, 1.0f );
        Matrix4x4 projection = cam.projectionMatrix;
        CalculateObliqueMatrix (ref projection, clipPlane);
        reflectionCamera.projectionMatrix = projection;

        reflectionCamera.cullingMask = ~(1<<4) & m_ReflectLayers.value; // never render water and system layers
        reflectionCamera.targetTexture = m_ReflectionTexture;
        reflectionCamera.Render();

        Material[] materials = renderer.sharedMaterials;
        foreach( Material mat in materials ) {
            if(mat.HasProperty("_PortalTex") )
                mat.SetTexture( "_PortalTex", 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.backgroundColor = src.backgroundColor;    
        dest.clearFlags = src.clearFlags;
        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 = "__PortalReflection" + 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( "Portal 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 and
    // http://aras-p.info/texts/obliqueortho.html
    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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1 Answer 1

up vote 2 down vote accepted

So after much working I found out this is a bug with Unity. It happens in their Deferred Lighting -> RenderingToTexture pipeline. What's happening is they are cutting it to only show the first pass.

I'll be filing a bug report to Unity, and hopefully this gets fixed soon. As a simple work around I'm just setting the portal camera to forward rendering path, it's still missing shadows, but at least it shows lights now.

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