Unity 5 Occlusion Culling Water Reflection flicker

So I’ve recently been having trouble with my Occlusion Culling disabling the objects when the player looks in the water’s reflection, but when the player doesn’t directly look at the water they partially re-enable.
Any suggestions on how to fix this?

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For anyone out there, this is the fix.

Replace this script into the water script

using System;
using System.Collections.Generic;
using UnityEngine;

namespace UnityStandardAssets.Water
{
    [ExecuteInEditMode] // Make water live-update even when not in play mode
    public class Water : MonoBehaviour
    {
        public enum WaterMode {
            Simple = 0,
            Reflective = 1,
            Refractive = 2,
        };
        public WaterMode m_WaterMode = WaterMode.Refractive;
        public bool m_DisablePixelLights = true;
        public int m_TextureSize = 256;
        public float m_ClipPlaneOffset = 0.07f;

        public bool m_TurnOffWaterOcclusion = true;

        public LayerMask m_ReflectLayers = -1;
        public LayerMask m_RefractLayers = -1;

        private Dictionary<Camera, Camera> m_ReflectionCameras = new Dictionary<Camera, Camera>(); // Camera -> Camera table
        private Dictionary<Camera, Camera> m_RefractionCameras = new Dictionary<Camera, Camera>(); // Camera -> Camera table

        private RenderTexture m_ReflectionTexture = null;
        private RenderTexture m_RefractionTexture = null;
        private WaterMode m_HardwareWaterSupport = WaterMode.Refractive;
        private int m_OldReflectionTextureSize = 0;
        private int m_OldRefractionTextureSize = 0;

        private static bool s_InsideWater = false;

        // This is called when it's known that the object will be rendered by some
        // camera. We render reflections / refractions 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 || !GetComponent<Renderer>() || !GetComponent<Renderer>().sharedMaterial || !GetComponent<Renderer>().enabled )
                return;

            Camera cam = Camera.current;
            if( !cam )
                return;

            // Safeguard from recursive water reflections.       
            if( s_InsideWater )
                return;
            s_InsideWater = true;

            // Actual water rendering mode depends on both the current setting AND
            // the hardware support. There's no point in rendering refraction textures
            // if they won't be visible in the end.
            m_HardwareWaterSupport = FindHardwareWaterSupport();
            WaterMode mode = GetWaterMode();

            Camera reflectionCamera, refractionCamera;
            CreateWaterObjects( cam, out reflectionCamera, out refractionCamera );

            // 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/refraction
            int oldPixelLightCount = QualitySettings.pixelLightCount;
            if( m_DisablePixelLights )
                QualitySettings.pixelLightCount = 0;

            UpdateCameraModes( cam, reflectionCamera );
            UpdateCameraModes( cam, refractionCamera );

            // Render reflection if needed
            if( mode >= WaterMode.Reflective )
            {
                // 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 );
                reflectionCamera.projectionMatrix = cam.CalculateObliqueMatrix(clipPlane);

                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(-euler.x, euler.y, euler.z);
                reflectionCamera.Render();
                reflectionCamera.transform.position = oldpos;
                GL.SetRevertBackfacing (false);
                GetComponent<Renderer>().sharedMaterial.SetTexture( "_ReflectionTex", m_ReflectionTexture );
            }

            // Render refraction
            if( mode >= WaterMode.Refractive )
            {
                refractionCamera.worldToCameraMatrix = cam.worldToCameraMatrix;

                // 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( refractionCamera, pos, normal, -1.0f );
                refractionCamera.projectionMatrix = cam.CalculateObliqueMatrix(clipPlane);

                refractionCamera.cullingMask = ~(1<<4) & m_RefractLayers.value; // never render water layer
                refractionCamera.targetTexture = m_RefractionTexture;
                refractionCamera.transform.position = cam.transform.position;
                refractionCamera.transform.rotation = cam.transform.rotation;
                refractionCamera.Render();
                GetComponent<Renderer>().sharedMaterial.SetTexture( "_RefractionTex", m_RefractionTexture );
            }

            // Restore pixel light count
            if( m_DisablePixelLights )
                QualitySettings.pixelLightCount = oldPixelLightCount;

            // Setup shader keywords based on water mode
            switch( mode )
            {
            case WaterMode.Simple:
                Shader.EnableKeyword( "WATER_SIMPLE" );
                Shader.DisableKeyword( "WATER_REFLECTIVE" );
                Shader.DisableKeyword( "WATER_REFRACTIVE" );
                break;
            case WaterMode.Reflective:
                Shader.DisableKeyword( "WATER_SIMPLE" );
                Shader.EnableKeyword( "WATER_REFLECTIVE" );
                Shader.DisableKeyword( "WATER_REFRACTIVE" );
                break;
            case WaterMode.Refractive:
                Shader.DisableKeyword( "WATER_SIMPLE" );
                Shader.DisableKeyword( "WATER_REFLECTIVE" );
                Shader.EnableKeyword( "WATER_REFRACTIVE" );
                break;
            }

            s_InsideWater = false;
        }


        // Cleanup all the objects we possibly have created
        void OnDisable()
        {
            if( m_ReflectionTexture ) {
                DestroyImmediate( m_ReflectionTexture );
                m_ReflectionTexture = null;
            }
            if( m_RefractionTexture ) {
                DestroyImmediate( m_RefractionTexture );
                m_RefractionTexture = null;
            }
            foreach (KeyValuePair<Camera, Camera> kvp in m_ReflectionCameras)
                DestroyImmediate( (kvp.Value).gameObject );
            m_ReflectionCameras.Clear();
            foreach (KeyValuePair<Camera, Camera> kvp in m_RefractionCameras)
                DestroyImmediate( (kvp.Value).gameObject );
            m_RefractionCameras.Clear();
        }


        // This just sets up some matrices in the material; for really
        // old cards to make water texture scroll.
        void Update()
        {
            if( !GetComponent<Renderer>() )
                return;
            Material mat = GetComponent<Renderer>().sharedMaterial;
            if( !mat )
                return;

            Vector4 waveSpeed = mat.GetVector( "WaveSpeed" );
            float waveScale = mat.GetFloat( "_WaveScale" );
            Vector4 waveScale4 = new Vector4(waveScale, waveScale, waveScale * 0.4f, waveScale * 0.45f);

            // Time since level load, and do intermediate calculations with doubles
            double t = Time.timeSinceLevelLoad / 20.0;
            Vector4 offsetClamped = new Vector4(
                (float)System.Math.IEEERemainder(waveSpeed.x * waveScale4.x * t, 1.0),
                (float)System.Math.IEEERemainder(waveSpeed.y * waveScale4.y * t, 1.0),
                (float)System.Math.IEEERemainder(waveSpeed.z * waveScale4.z * t, 1.0),
                (float)System.Math.IEEERemainder(waveSpeed.w * waveScale4.w * t, 1.0)
            );

            mat.SetVector( "_WaveOffset", offsetClamped );
            mat.SetVector( "_WaveScale4", waveScale4 );

            Vector3 waterSize = GetComponent<Renderer>().bounds.size;       
            Vector3 scale = new Vector3( waterSize.x*waveScale4.x, waterSize.z*waveScale4.y, 1 );
            Matrix4x4 scrollMatrix = Matrix4x4.TRS( new Vector3(offsetClamped.x,offsetClamped.y,0), Quaternion.identity, scale );
            mat.SetMatrix( "_WaveMatrix", scrollMatrix );

            scale = new Vector3( waterSize.x*waveScale4.z, waterSize.z*waveScale4.w, 1 );
            scrollMatrix = Matrix4x4.TRS( new Vector3(offsetClamped.z,offsetClamped.w,0), Quaternion.identity, scale );
            mat.SetMatrix( "_WaveMatrix2", scrollMatrix );
        }

        private void UpdateCameraModes( Camera src, Camera dest )
        {
            if( dest == null )
                return;
            // set water 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 for water
        private void CreateWaterObjects( Camera currentCamera, out Camera reflectionCamera, out Camera refractionCamera )
        {
            WaterMode mode = GetWaterMode();

            reflectionCamera = null;
            refractionCamera = null;

            if( mode >= WaterMode.Reflective )
            {
                // 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 = "__WaterReflection" + GetInstanceID();
                    m_ReflectionTexture.isPowerOfTwo = true;
                    m_ReflectionTexture.hideFlags = HideFlags.DontSave;
                    m_OldReflectionTextureSize = m_TextureSize;

                }

                // Camera for reflection
                m_ReflectionCameras.TryGetValue(currentCamera, out reflectionCamera);
                if (!reflectionCamera) // catch both not-in-dictionary and in-dictionary-but-deleted-GO
                {
                    GameObject go = new GameObject( "Water Refl Camera id" + GetInstanceID() + " for " + currentCamera.GetInstanceID(), typeof(Camera), typeof(Skybox) );
                    reflectionCamera = go.GetComponent<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;

                    if (m_TurnOffWaterOcclusion)
                        reflectionCamera.useOcclusionCulling = false;
                }
            }

            if( mode >= WaterMode.Refractive )
            {
                // Refraction render texture
                if( !m_RefractionTexture || m_OldRefractionTextureSize != m_TextureSize )
                {
                    if( m_RefractionTexture )
                        DestroyImmediate( m_RefractionTexture );
                    m_RefractionTexture = new RenderTexture( m_TextureSize, m_TextureSize, 16 );
                    m_RefractionTexture.name = "__WaterRefraction" + GetInstanceID();
                    m_RefractionTexture.isPowerOfTwo = true;
                    m_RefractionTexture.hideFlags = HideFlags.DontSave;
                    m_OldRefractionTextureSize = m_TextureSize;
                }

                // Camera for refraction
                m_RefractionCameras.TryGetValue(currentCamera, out refractionCamera);
                if (!refractionCamera) // catch both not-in-dictionary and in-dictionary-but-deleted-GO
                {
                    GameObject go = new GameObject( "Water Refr Camera id" + GetInstanceID() + " for " + currentCamera.GetInstanceID(), typeof(Camera), typeof(Skybox) );
                    refractionCamera = go.GetComponent<Camera>();
                    refractionCamera.enabled = false;
                    refractionCamera.transform.position = transform.position;
                    refractionCamera.transform.rotation = transform.rotation;
                    refractionCamera.gameObject.AddComponent<FlareLayer>();
                    go.hideFlags = HideFlags.HideAndDontSave;
                    m_RefractionCameras[currentCamera] = refractionCamera;

                    if (m_TurnOffWaterOcclusion)
                        refractionCamera.useOcclusionCulling = false;
                }
            }
        }

        private WaterMode GetWaterMode()
        {
            if( m_HardwareWaterSupport < m_WaterMode )
                return m_HardwareWaterSupport;
            else
                return m_WaterMode;
        }

        private WaterMode FindHardwareWaterSupport()
        {
            if( !SystemInfo.supportsRenderTextures || !GetComponent<Renderer>() )
                return WaterMode.Simple;

            Material mat = GetComponent<Renderer>().sharedMaterial;
            if( !mat )
                return WaterMode.Simple;

            string mode = mat.GetTag("WATERMODE", false);
            if( mode == "Refractive" )
                return WaterMode.Refractive;
            if( mode == "Reflective" )
                return WaterMode.Reflective;

            return WaterMode.Simple;
        }

        // 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) );
        }

        // 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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Awesome share thank you!

This is the only useful answer to this topic in the whole internet!

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You, my friend, are a hero!

1 Like

you’re a god :slight_smile:

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