Water.cs

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using UnityEngine;
using System.Collections;


[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 LayerMask m_ReflectLayers = -1;
    public LayerMask m_RefractLayers = -1;
        
    private Hashtable m_ReflectionCameras = new Hashtable(); // Camera -> Camera table
    private Hashtable m_RefractionCameras = new Hashtable(); // 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 );
            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.invertCulling = 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.invertCulling = 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 );
            Matrix4x4 projection = cam.projectionMatrix;
            CalculateObliqueMatrix (ref projection, clipPlane);
            refractionCamera.projectionMatrix = projection;
            
            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( DictionaryEntry kvp in m_ReflectionCameras )
            DestroyImmediate( ((Camera)kvp.Value).gameObject );
        m_ReflectionCameras.Clear();
        foreach( DictionaryEntry kvp in m_RefractionCameras )
            DestroyImmediate( ((Camera)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" );
        float t = Time.time / 40.0f;
        
        Vector3 offset = new Vector3( t * waveSpeed.x, t * waveSpeed.y, 0 );
        Vector3 scale = new Vector3( 1.0f/waveScale, 1.0f/waveScale, 1 );
        Matrix4x4 scrollMatrix = Matrix4x4.TRS( offset, Quaternion.identity, scale );
        mat.SetMatrix( "_WaveMatrix", scrollMatrix );
        
        offset = new Vector3( t * waveSpeed.z, t * waveSpeed.w, 0 );
        scrollMatrix = Matrix4x4.TRS( offset, Quaternion.identity, scale * 0.45f );
        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
            reflectionCamera = m_ReflectionCameras[currentCamera] as Camera;
            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( 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
            refractionCamera = m_RefractionCameras[currentCamera] as Camera;
            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;
            }
        }
    }
    
    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) );
    }
    
    // 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;
    }
}