/*
-----------------------------------------------------------------------------
This source file is part of OGRE
    (Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org

Copyright (c) 2000-2006 Torus Knot Software Ltd
Also see acknowledgements in Readme.html

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA, or go to
http://www.gnu.org/copyleft/lesser.txt.

You may alternatively use this source under the terms of a specific version of
the OGRE Unrestricted License provided you have obtained such a license from
Torus Knot Software Ltd.
-----------------------------------------------------------------------------
*/
#include "OgreStableHeaders.h"
#include "OgreFrustum.h"

#include "OgreMath.h"
#include "OgreMatrix3.h"
#include "OgreSceneNode.h"
#include "OgreSphere.h"
#include "OgreLogManager.h"
#include "OgreException.h"
#include "OgreRoot.h"
#include "OgreCamera.h"
#include "OgreHardwareBufferManager.h"
#include "OgreHardwareVertexBuffer.h"
#include "OgreHardwareIndexBuffer.h"
#include "OgreMaterialManager.h"
#include "OgreRenderSystem.h"

namespace Ogre {

    String Frustum::msMovableType = "Frustum";
    const Real Frustum::INFINITE_FAR_PLANE_ADJUST = 0.00001;
    //-----------------------------------------------------------------------
    Frustum::Frustum() : 
        mProjType(PT_PERSPECTIVE), 
        mFOVy(Radian(Math::PI/4.0)), 
        mFarDist(100000.0f), 
        mNearDist(100.0f), 
        mAspect(1.33333333333333f), 
        mFrustumOffset(Vector2::ZERO),
        mFocalLength(1.0f),
        mLastParentOrientation(Quaternion::IDENTITY),
        mLastParentPosition(Vector3::ZERO),
        mRecalcFrustum(true), 
        mRecalcView(true), 
        mRecalcFrustumPlanes(true),
        mRecalcWorldSpaceCorners(true),
        mRecalcVertexData(true),
		mCustomViewMatrix(false),
		mCustomProjMatrix(false),
        mReflect(false), 
        mLinkedReflectPlane(0),
        mObliqueDepthProjection(false), 
        mLinkedObliqueProjPlane(0)
    {
        // Initialise material
        mMaterial = MaterialManager::getSingleton().getByName("BaseWhiteNoLighting");
        
        // Alter superclass members
        mVisible = false;
        mParentNode = 0;

        mLastLinkedReflectionPlane.normal = Vector3::ZERO;
        mLastLinkedObliqueProjPlane.normal = Vector3::ZERO;


        updateView();
        updateFrustum();
    }

    //-----------------------------------------------------------------------
    Frustum::~Frustum()
    {
        // Do nothing
    }

    //-----------------------------------------------------------------------
    void Frustum::setFOVy(const Radian& fov)
    {
        mFOVy = fov;
        invalidateFrustum();
    }

    //-----------------------------------------------------------------------
    const Radian& Frustum::getFOVy(void) const
    {
        return mFOVy;
    }


    //-----------------------------------------------------------------------
    void Frustum::setFarClipDistance(Real farPlane)
    {
        mFarDist = farPlane;
        invalidateFrustum();
    }

    //-----------------------------------------------------------------------
    Real Frustum::getFarClipDistance(void) const
    {
        return mFarDist;
    }

    //-----------------------------------------------------------------------
    void Frustum::setNearClipDistance(Real nearPlane)
    {
        if (nearPlane <= 0)
            OGRE_EXCEPT(Exception::ERR_INVALIDPARAMS, "Near clip distance must be greater than zero.",
                "Frustum::setNearClipDistance");
        mNearDist = nearPlane;
        invalidateFrustum();
    }

    //-----------------------------------------------------------------------
    Real Frustum::getNearClipDistance(void) const
    {
        return mNearDist;
    }

    //---------------------------------------------------------------------
    void Frustum::setFrustumOffset(const Vector2& offset)
    {
        mFrustumOffset = offset;
        invalidateFrustum();
    }
    //---------------------------------------------------------------------
    void Frustum::setFrustumOffset(Real horizontal, Real vertical)
    {
        setFrustumOffset(Vector2(horizontal, vertical));
    }
    //---------------------------------------------------------------------
    const Vector2& Frustum::getFrustumOffset() const
    {
        return mFrustumOffset;
    }
    //---------------------------------------------------------------------
    void Frustum::setFocalLength(Real focalLength)
    {
        if (focalLength <= 0)
        {
            OGRE_EXCEPT(Exception::ERR_INVALIDPARAMS,
                "Focal length must be greater than zero.",
                "Frustum::setFocalLength");
        }

        mFocalLength = focalLength;
        invalidateFrustum();
    }
    //---------------------------------------------------------------------
    Real Frustum::getFocalLength() const
    {
        return mFocalLength;
    }
    //-----------------------------------------------------------------------
    const Matrix4& Frustum::getProjectionMatrix(void) const
    {

        updateFrustum();

        return mProjMatrix;
    }
    //-----------------------------------------------------------------------
    const Matrix4& Frustum::getProjectionMatrixWithRSDepth(void) const
    {

        updateFrustum();

        return mProjMatrixRSDepth;
    }
    //-----------------------------------------------------------------------
    const Matrix4& Frustum::getProjectionMatrixRS(void) const
    {

        updateFrustum();

        return mProjMatrixRS;
    }
    //-----------------------------------------------------------------------
    const Matrix4& Frustum::getViewMatrix(void) const
    {
        updateView();

        return mViewMatrix;

    }

    //-----------------------------------------------------------------------
    const Plane* Frustum::getFrustumPlanes(void) const
    {
        // Make any pending updates to the calculated frustum planes
        updateFrustumPlanes();

        return mFrustumPlanes;
    }

    //-----------------------------------------------------------------------
    const Plane& Frustum::getFrustumPlane(unsigned short plane) const
    {
        // Make any pending updates to the calculated frustum planes
        updateFrustumPlanes();

        return mFrustumPlanes[plane];

    }

    //-----------------------------------------------------------------------
    bool Frustum::isVisible(const AxisAlignedBox& bound, FrustumPlane* culledBy) const
    {
        // Null boxes always invisible
        if (bound.isNull()) return false;

        // Infinite boxes always visible
        if (bound.isInfinite()) return true;

        // Make any pending updates to the calculated frustum planes
        updateFrustumPlanes();

        // Get centre of the box
        Vector3 centre = bound.getCenter();
        // Get the half-size of the box
        Vector3 halfSize = bound.getHalfSize();

        // For each plane, see if all points are on the negative side
        // If so, object is not visible
        for (int plane = 0; plane < 6; ++plane)
        {
            // Skip far plane if infinite view frustum
            if (plane == FRUSTUM_PLANE_FAR && mFarDist == 0)
                continue;

            Plane::Side side = mFrustumPlanes[plane].getSide(centre, halfSize);
            if (side == Plane::NEGATIVE_SIDE)
            {
                // ALL corners on negative side therefore out of view
                if (culledBy)
                    *culledBy = (FrustumPlane)plane;
                return false;
            }

        }

        return true;
    }

    //-----------------------------------------------------------------------
    bool Frustum::isVisible(const Vector3& vert, FrustumPlane* culledBy) const
    {
        // Make any pending updates to the calculated frustum planes
        updateFrustumPlanes();

        // For each plane, see if all points are on the negative side
        // If so, object is not visible
        for (int plane = 0; plane < 6; ++plane)
        {
            // Skip far plane if infinite view frustum
            if (plane == FRUSTUM_PLANE_FAR && mFarDist == 0)
                continue;

            if (mFrustumPlanes[plane].getSide(vert) == Plane::NEGATIVE_SIDE)
            {
                // ALL corners on negative side therefore out of view
                if (culledBy)
                    *culledBy = (FrustumPlane)plane;
                return false;
            }

        }

        return true;
    }

    //-----------------------------------------------------------------------
    bool Frustum::isVisible(const Sphere& sphere, FrustumPlane* culledBy) const
    {
        // Make any pending updates to the calculated frustum planes
        updateFrustumPlanes();

        // For each plane, see if sphere is on negative side
        // If so, object is not visible
        for (int plane = 0; plane < 6; ++plane)
        {
            // Skip far plane if infinite view frustum
            if (plane == FRUSTUM_PLANE_FAR && mFarDist == 0)
                continue;

            // If the distance from sphere center to plane is negative, and 'more negative' 
            // than the radius of the sphere, sphere is outside frustum
            if (mFrustumPlanes[plane].getDistance(sphere.getCenter()) < -sphere.getRadius())
            {
                // ALL corners on negative side therefore out of view
                if (culledBy)
                    *culledBy = (FrustumPlane)plane;
                return false;
            }

        }

        return true;
    }
    //-----------------------------------------------------------------------
    void Frustum::calcProjectionParameters(Real& left, Real& right, Real& bottom, Real& top) const
    { 
		if (mCustomProjMatrix)
		{
			// Convert clipspace corners to camera space
			Matrix4 invProj = mProjMatrix.inverse();
			Vector3 topLeft(-0.5f, 0.5f, 0.0f);
			Vector3 bottomRight(0.5f, -0.5f, 0.0f);

			topLeft = invProj * topLeft;
			bottomRight = invProj * bottomRight;

			left = topLeft.x;
			top = topLeft.y;
			right = bottomRight.x;
			bottom = bottomRight.y;

		}
		else
		{
			// Calculate general projection parameters

			Radian thetaY (mFOVy * 0.5f);
			Real tanThetaY = Math::Tan(thetaY);
			Real tanThetaX = tanThetaY * mAspect;

			// Unknow how to apply frustum offset to orthographic camera, just ignore here
			Real nearFocal = (mProjType == PT_PERSPECTIVE) ? mNearDist / mFocalLength : 0;
			Real nearOffsetX = mFrustumOffset.x * nearFocal;
			Real nearOffsetY = mFrustumOffset.y * nearFocal;
			Real half_w = tanThetaX * mNearDist;
			Real half_h = tanThetaY * mNearDist;

			left   = - half_w + nearOffsetX;
			right  = + half_w + nearOffsetX;
			bottom = - half_h + nearOffsetY;
			top    = + half_h + nearOffsetY;
		}
    }
	//-----------------------------------------------------------------------
	void Frustum::updateFrustumImpl(void) const
	{
		// Common calcs
		Real left, right, bottom, top;
		calcProjectionParameters(left, right, bottom, top);

		if (!mCustomProjMatrix)
		{

			// The code below will dealing with general projection 
			// parameters, similar glFrustum and glOrtho.
			// Doesn't optimise manually except division operator, so the 
			// code more self-explaining.

			Real inv_w = 1 / (right - left);
			Real inv_h = 1 / (top - bottom);
			Real inv_d = 1 / (mFarDist - mNearDist);

			// Recalc if frustum params changed
			if (mProjType == PT_PERSPECTIVE)
			{
				// Calc matrix elements
				Real A = 2 * mNearDist * inv_w;
				Real B = 2 * mNearDist * inv_h;
				Real C = (right + left) * inv_w;
				Real D = (top + bottom) * inv_h;
				Real q, qn;
				if (mFarDist == 0)
				{
					// Infinite far plane
					q = Frustum::INFINITE_FAR_PLANE_ADJUST - 1;
					qn = mNearDist * (Frustum::INFINITE_FAR_PLANE_ADJUST - 2);
				}
				else
				{
					q = - (mFarDist + mNearDist) * inv_d;
					qn = -2 * (mFarDist * mNearDist) * inv_d;
				}

				// NB: This creates 'uniform' perspective projection matrix,
				// which depth range [-1,1], right-handed rules
				//
				// [ A   0   C   0  ]
				// [ 0   B   D   0  ]
				// [ 0   0   q   qn ]
				// [ 0   0   -1  0  ]
				//
				// A = 2 * near / (right - left)
				// B = 2 * near / (top - bottom)
				// C = (right + left) / (right - left)
				// D = (top + bottom) / (top - bottom)
				// q = - (far + near) / (far - near)
				// qn = - 2 * (far * near) / (far - near)

				mProjMatrix = Matrix4::ZERO;
				mProjMatrix[0][0] = A;
				mProjMatrix[0][2] = C;
				mProjMatrix[1][1] = B;
				mProjMatrix[1][2] = D;
				mProjMatrix[2][2] = q;
				mProjMatrix[2][3] = qn;
				mProjMatrix[3][2] = -1;

				if (mObliqueDepthProjection)
				{
					// Translate the plane into view space

					// Don't use getViewMatrix here, incase overrided by 
					// camera and return a cull frustum view matrix
					updateView();
					Plane plane = mViewMatrix * mObliqueProjPlane;

					// Thanks to Eric Lenyel for posting this calculation 
					// at www.terathon.com

					// Calculate the clip-space corner point opposite the 
					// clipping plane
					// as (sgn(clipPlane.x), sgn(clipPlane.y), 1, 1) and
					// transform it into camera space by multiplying it
					// by the inverse of the projection matrix

					/* generalised version
					Vector4 q = matrix.inverse() * 
					Vector4(Math::Sign(plane.normal.x), 
					Math::Sign(plane.normal.y), 1.0f, 1.0f);
					*/
					Vector4 q;
					q.x = (Math::Sign(plane.normal.x) + mProjMatrix[0][2]) / mProjMatrix[0][0];
					q.y = (Math::Sign(plane.normal.y) + mProjMatrix[1][2]) / mProjMatrix[1][1];
					q.z = -1;
					q.w = (1 + mProjMatrix[2][2]) / mProjMatrix[2][3];

					// Calculate the scaled plane vector
					Vector4 clipPlane4d(plane.normal.x, plane.normal.y, plane.normal.z, plane.d);
					Vector4 c = clipPlane4d * (2 / (clipPlane4d.dotProduct(q)));

					// Replace the third row of the projection matrix
					mProjMatrix[2][0] = c.x;
					mProjMatrix[2][1] = c.y;
					mProjMatrix[2][2] = c.z + 1;
					mProjMatrix[2][3] = c.w; 
				}
			} // perspective
			else if (mProjType == PT_ORTHOGRAPHIC)
			{
				Real A = 2 * inv_w;
				Real B = 2 * inv_h;
				Real C = - (right + left) * inv_w;
				Real D = - (top + bottom) * inv_h;
				Real q, qn;
				if (mFarDist == 0)
				{
					// Can not do infinite far plane here, avoid divided zero only
					q = - Frustum::INFINITE_FAR_PLANE_ADJUST / mNearDist;
					qn = - Frustum::INFINITE_FAR_PLANE_ADJUST - 1;
				}
				else
				{
					q = - 2 * inv_d;
					qn = - (mFarDist + mNearDist)  * inv_d;
				}

				// NB: This creates 'uniform' orthographic projection matrix,
				// which depth range [-1,1], right-handed rules
				//
				// [ A   0   0   C  ]
				// [ 0   B   0   D  ]
				// [ 0   0   q   qn ]
				// [ 0   0   0   1  ]
				//
				// A = 2 * / (right - left)
				// B = 2 * / (top - bottom)
				// C = - (right + left) / (right - left)
				// D = - (top + bottom) / (top - bottom)
				// q = - 2 / (far - near)
				// qn = - (far + near) / (far - near)

				mProjMatrix = Matrix4::ZERO;
				mProjMatrix[0][0] = A;
				mProjMatrix[0][3] = C;
				mProjMatrix[1][1] = B;
				mProjMatrix[1][3] = D;
				mProjMatrix[2][2] = q;
				mProjMatrix[2][3] = qn;
				mProjMatrix[3][3] = 1;
			} // ortho
		} // !mCustomProjMatrix

		RenderSystem* renderSystem = Root::getSingleton().getRenderSystem();
		// API specific
		renderSystem->_convertProjectionMatrix(mProjMatrix, mProjMatrixRS);
		// API specific for Gpu Programs
		renderSystem->_convertProjectionMatrix(mProjMatrix, mProjMatrixRSDepth, true);


		// Calculate bounding box (local)
		// Box is from 0, down -Z, max dimensions as determined from far plane
		// If infinite view frustum just pick a far value
		Real farDist = (mFarDist == 0) ? 100000 : mFarDist;
		// Near plane bounds
		Vector3 min(left, bottom, -farDist);
		Vector3 max(right, top, 0);

		if (mCustomProjMatrix)
		{
			// Some custom projection matrices can have unusual inverted settings
			// So make sure the AABB is the right way around to start with
			Vector3 tmp = min;
			min.makeFloor(max);
			max.makeCeil(tmp);
		}

		if (mProjType == PT_PERSPECTIVE)
		{
			// Merge with far plane bounds
			Real radio = farDist / mNearDist;
			min.makeFloor(Vector3(left * radio, bottom * radio, -farDist));
			max.makeCeil(Vector3(right * radio, top * radio, 0));
		}
		mBoundingBox.setExtents(min, max);

		mRecalcFrustum = false;

		// Signal to update frustum clipping planes
		mRecalcFrustumPlanes = true;
	}
    //-----------------------------------------------------------------------
    void Frustum::updateFrustum(void) const
    {
        if (isFrustumOutOfDate())
        {
			updateFrustumImpl();
        }
    }

    //-----------------------------------------------------------------------
    void Frustum::updateVertexData(void) const
    {
        if (mRecalcVertexData)
        {
            if (mVertexData.vertexBufferBinding->getBufferCount() <= 0)
            {
                // Initialise vertex & index data
                mVertexData.vertexDeclaration->addElement(0, 0, VET_FLOAT3, VES_POSITION);
                mVertexData.vertexCount = 32;
                mVertexData.vertexStart = 0;
                mVertexData.vertexBufferBinding->setBinding( 0,
                    HardwareBufferManager::getSingleton().createVertexBuffer(
                        sizeof(float)*3, 32, HardwareBuffer::HBU_DYNAMIC_WRITE_ONLY) );
            }

            // Note: Even though we can dealing with general projection matrix here,
            //       but because it's incompatibly with infinite far plane, thus, we
            //       still need to working with projection parameters.

            // Calc near plane corners
            Real vpLeft, vpRight, vpBottom, vpTop;
            calcProjectionParameters(vpLeft, vpRight, vpBottom, vpTop);

            // Treat infinite fardist as some arbitrary far value
            Real farDist = (mFarDist == 0) ? 100000 : mFarDist;

            // Calc far palne corners
            Real radio = mProjType == PT_PERSPECTIVE ? farDist / mNearDist : 1;
            Real farLeft = vpLeft * radio;
            Real farRight = vpRight * radio;
            Real farBottom = vpBottom * radio;
            Real farTop = vpTop * radio;

            // Calculate vertex positions (local)
            // 0 is the origin
            // 1, 2, 3, 4 are the points on the near plane, top left first, clockwise
            // 5, 6, 7, 8 are the points on the far plane, top left first, clockwise
            HardwareVertexBufferSharedPtr vbuf = mVertexData.vertexBufferBinding->getBuffer(0);
            float* pFloat = static_cast<float*>(vbuf->lock(HardwareBuffer::HBL_DISCARD));

            // near plane (remember frustum is going in -Z direction)
            *pFloat++ = vpLeft;  *pFloat++ = vpTop;    *pFloat++ = -mNearDist;
            *pFloat++ = vpRight; *pFloat++ = vpTop;    *pFloat++ = -mNearDist;

            *pFloat++ = vpRight; *pFloat++ = vpTop;    *pFloat++ = -mNearDist;
            *pFloat++ = vpRight; *pFloat++ = vpBottom; *pFloat++ = -mNearDist;

            *pFloat++ = vpRight; *pFloat++ = vpBottom; *pFloat++ = -mNearDist;
            *pFloat++ = vpLeft;  *pFloat++ = vpBottom; *pFloat++ = -mNearDist;

            *pFloat++ = vpLeft;  *pFloat++ = vpBottom; *pFloat++ = -mNearDist;
            *pFloat++ = vpLeft;  *pFloat++ = vpTop;    *pFloat++ = -mNearDist;

            // far plane (remember frustum is going in -Z direction)
            *pFloat++ = farLeft;  *pFloat++ = farTop;    *pFloat++ = -farDist;
            *pFloat++ = farRight; *pFloat++ = farTop;    *pFloat++ = -farDist;

            *pFloat++ = farRight; *pFloat++ = farTop;    *pFloat++ = -farDist;
            *pFloat++ = farRight; *pFloat++ = farBottom; *pFloat++ = -farDist;

            *pFloat++ = farRight; *pFloat++ = farBottom; *pFloat++ = -farDist;
            *pFloat++ = farLeft;  *pFloat++ = farBottom; *pFloat++ = -farDist;

            *pFloat++ = farLeft;  *pFloat++ = farBottom; *pFloat++ = -farDist;
            *pFloat++ = farLeft;  *pFloat++ = farTop;    *pFloat++ = -farDist;

            // Sides of the pyramid
            *pFloat++ = 0.0f;    *pFloat++ = 0.0f;   *pFloat++ = 0.0f;
            *pFloat++ = vpLeft;  *pFloat++ = vpTop;  *pFloat++ = -mNearDist;

            *pFloat++ = 0.0f;    *pFloat++ = 0.0f;   *pFloat++ = 0.0f;
            *pFloat++ = vpRight; *pFloat++ = vpTop;    *pFloat++ = -mNearDist;

            *pFloat++ = 0.0f;    *pFloat++ = 0.0f;   *pFloat++ = 0.0f;
            *pFloat++ = vpRight; *pFloat++ = vpBottom; *pFloat++ = -mNearDist;

            *pFloat++ = 0.0f;    *pFloat++ = 0.0f;   *pFloat++ = 0.0f;
            *pFloat++ = vpLeft;  *pFloat++ = vpBottom; *pFloat++ = -mNearDist;

            // Sides of the box

            *pFloat++ = vpLeft;  *pFloat++ = vpTop;  *pFloat++ = -mNearDist;
            *pFloat++ = farLeft;  *pFloat++ = farTop;  *pFloat++ = -farDist;

            *pFloat++ = vpRight; *pFloat++ = vpTop;    *pFloat++ = -mNearDist;
            *pFloat++ = farRight; *pFloat++ = farTop;    *pFloat++ = -farDist;

            *pFloat++ = vpRight; *pFloat++ = vpBottom; *pFloat++ = -mNearDist;
            *pFloat++ = farRight; *pFloat++ = farBottom; *pFloat++ = -farDist;

            *pFloat++ = vpLeft;  *pFloat++ = vpBottom; *pFloat++ = -mNearDist;
            *pFloat++ = farLeft;  *pFloat++ = farBottom; *pFloat++ = -farDist;


            vbuf->unlock();

            mRecalcVertexData = false;
        }
    }

    //-----------------------------------------------------------------------
    bool Frustum::isViewOutOfDate(void) const
    {
        // Attached to node?
        if (mParentNode)
        {
            if (mRecalcView ||
                mParentNode->_getDerivedOrientation() != mLastParentOrientation ||
                mParentNode->_getDerivedPosition() != mLastParentPosition)
            {
                // Ok, we're out of date with SceneNode we're attached to
                mLastParentOrientation = mParentNode->_getDerivedOrientation();
                mLastParentPosition = mParentNode->_getDerivedPosition();
                mRecalcView = true;
            }
        }
        // Deriving reflection from linked plane?
        if (mLinkedReflectPlane && 
            !(mLastLinkedReflectionPlane == mLinkedReflectPlane->_getDerivedPlane()))
        {
            mReflectPlane = mLinkedReflectPlane->_getDerivedPlane();
            mReflectMatrix = Math::buildReflectionMatrix(mReflectPlane);
            mLastLinkedReflectionPlane = mLinkedReflectPlane->_getDerivedPlane();
            mRecalcView = true;
        }

        return mRecalcView;
    }

    //-----------------------------------------------------------------------
    bool Frustum::isFrustumOutOfDate(void) const
    {
        // Deriving custom near plane from linked plane?
        if (mObliqueDepthProjection)
        {
            // Out of date when view out of data since plane needs to be in view space
            if (isViewOutOfDate())
            {
                mRecalcFrustum = true;
            }
            // Update derived plane
            if (mLinkedObliqueProjPlane && 
                !(mLastLinkedObliqueProjPlane == mLinkedObliqueProjPlane->_getDerivedPlane()))
            {
                mObliqueProjPlane = mLinkedObliqueProjPlane->_getDerivedPlane();
                mLastLinkedObliqueProjPlane = mObliqueProjPlane;
                mRecalcFrustum = true;
            }
        }

        return mRecalcFrustum;
    }

    //-----------------------------------------------------------------------
	void Frustum::updateViewImpl(void) const
	{
		// ----------------------
		// Update the view matrix
		// ----------------------

		// View matrix is:
		//
		//  [ Lx  Uy  Dz  Tx  ]
		//  [ Lx  Uy  Dz  Ty  ]
		//  [ Lx  Uy  Dz  Tz  ]
		//  [ 0   0   0   1   ]
		//
		// Where T = -(Transposed(Rot) * Pos)

		// This is most efficiently done using 3x3 Matrices

		// Get orientation from quaternion

		if (!mCustomViewMatrix)
		{
			Matrix3 rot;
			const Quaternion& orientation = getOrientationForViewUpdate();
			const Vector3& position = getPositionForViewUpdate();
			orientation.ToRotationMatrix(rot);

			// Make the translation relative to new axes
			Matrix3 rotT = rot.Transpose();
			Vector3 trans = -rotT * position;

			// Make final matrix
			mViewMatrix = Matrix4::IDENTITY;
			mViewMatrix = rotT; // fills upper 3x3
			mViewMatrix[0][3] = trans.x;
			mViewMatrix[1][3] = trans.y;
			mViewMatrix[2][3] = trans.z;

			// Deal with reflections
			if (mReflect)
			{
				mViewMatrix = mViewMatrix * mReflectMatrix;
			}
		}

		mRecalcView = false;

		// Signal to update frustum clipping planes
		mRecalcFrustumPlanes = true;
		// Signal to update world space corners
		mRecalcWorldSpaceCorners = true;
		// Signal to update frustum if oblique plane enabled,
		// since plane needs to be in view space
		if (mObliqueDepthProjection)
		{
			mRecalcFrustum = true;
		}
	}
	//-----------------------------------------------------------------------
    void Frustum::updateView(void) const
    {
        if (isViewOutOfDate())
        {
			updateViewImpl();
        }
    }

	//-----------------------------------------------------------------------
	void Frustum::updateFrustumPlanesImpl(void) const
	{
		// -------------------------
		// Update the frustum planes
		// -------------------------
		Matrix4 combo = mProjMatrix * mViewMatrix;

		mFrustumPlanes[FRUSTUM_PLANE_LEFT].normal.x = combo[3][0] + combo[0][0];
		mFrustumPlanes[FRUSTUM_PLANE_LEFT].normal.y = combo[3][1] + combo[0][1];
		mFrustumPlanes[FRUSTUM_PLANE_LEFT].normal.z = combo[3][2] + combo[0][2];
		mFrustumPlanes[FRUSTUM_PLANE_LEFT].d = combo[3][3] + combo[0][3];

		mFrustumPlanes[FRUSTUM_PLANE_RIGHT].normal.x = combo[3][0] - combo[0][0];
		mFrustumPlanes[FRUSTUM_PLANE_RIGHT].normal.y = combo[3][1] - combo[0][1];
		mFrustumPlanes[FRUSTUM_PLANE_RIGHT].normal.z = combo[3][2] - combo[0][2];
		mFrustumPlanes[FRUSTUM_PLANE_RIGHT].d = combo[3][3] - combo[0][3];

		mFrustumPlanes[FRUSTUM_PLANE_TOP].normal.x = combo[3][0] - combo[1][0];
		mFrustumPlanes[FRUSTUM_PLANE_TOP].normal.y = combo[3][1] - combo[1][1];
		mFrustumPlanes[FRUSTUM_PLANE_TOP].normal.z = combo[3][2] - combo[1][2];
		mFrustumPlanes[FRUSTUM_PLANE_TOP].d = combo[3][3] - combo[1][3];

		mFrustumPlanes[FRUSTUM_PLANE_BOTTOM].normal.x = combo[3][0] + combo[1][0];
		mFrustumPlanes[FRUSTUM_PLANE_BOTTOM].normal.y = combo[3][1] + combo[1][1];
		mFrustumPlanes[FRUSTUM_PLANE_BOTTOM].normal.z = combo[3][2] + combo[1][2];
		mFrustumPlanes[FRUSTUM_PLANE_BOTTOM].d = combo[3][3] + combo[1][3];

		mFrustumPlanes[FRUSTUM_PLANE_NEAR].normal.x = combo[3][0] + combo[2][0];
		mFrustumPlanes[FRUSTUM_PLANE_NEAR].normal.y = combo[3][1] + combo[2][1];
		mFrustumPlanes[FRUSTUM_PLANE_NEAR].normal.z = combo[3][2] + combo[2][2];
		mFrustumPlanes[FRUSTUM_PLANE_NEAR].d = combo[3][3] + combo[2][3];

		mFrustumPlanes[FRUSTUM_PLANE_FAR].normal.x = combo[3][0] - combo[2][0];
		mFrustumPlanes[FRUSTUM_PLANE_FAR].normal.y = combo[3][1] - combo[2][1];
		mFrustumPlanes[FRUSTUM_PLANE_FAR].normal.z = combo[3][2] - combo[2][2];
		mFrustumPlanes[FRUSTUM_PLANE_FAR].d = combo[3][3] - combo[2][3];

		// Renormalise any normals which were not unit length
		for(int i=0; i<6; i++ ) 
		{
			float length = mFrustumPlanes[i].normal.normalise();
			mFrustumPlanes[i].d /= length;
		}

		mRecalcFrustumPlanes = false;
	}
    //-----------------------------------------------------------------------
    void Frustum::updateFrustumPlanes(void) const
    {
        updateView();
        updateFrustum();

        if (mRecalcFrustumPlanes)
        {
			updateFrustumPlanesImpl();
        }
    }
	//-----------------------------------------------------------------------
	void Frustum::updateWorldSpaceCornersImpl(void) const
	{
		Matrix4 eyeToWorld = mViewMatrix.inverseAffine();

		// Note: Even though we can dealing with general projection matrix here,
		//       but because it's incompatibly with infinite far plane, thus, we
		//       still need to working with projection parameters.

		// Calc near plane corners
		Real nearLeft, nearRight, nearBottom, nearTop;
		calcProjectionParameters(nearLeft, nearRight, nearBottom, nearTop);

		// Treat infinite fardist as some arbitrary far value
		Real farDist = (mFarDist == 0) ? 100000 : mFarDist;

		// Calc far palne corners
		Real radio = mProjType == PT_PERSPECTIVE ? farDist / mNearDist : 1;
		Real farLeft = nearLeft * radio;
		Real farRight = nearRight * radio;
		Real farBottom = nearBottom * radio;
		Real farTop = nearTop * radio;

		// near
		mWorldSpaceCorners[0] = eyeToWorld.transformAffine(Vector3(nearRight, nearTop,    -mNearDist));
		mWorldSpaceCorners[1] = eyeToWorld.transformAffine(Vector3(nearLeft,  nearTop,    -mNearDist));
		mWorldSpaceCorners[2] = eyeToWorld.transformAffine(Vector3(nearLeft,  nearBottom, -mNearDist));
		mWorldSpaceCorners[3] = eyeToWorld.transformAffine(Vector3(nearRight, nearBottom, -mNearDist));
		// far
		mWorldSpaceCorners[4] = eyeToWorld.transformAffine(Vector3(farRight,  farTop,     -farDist));
		mWorldSpaceCorners[5] = eyeToWorld.transformAffine(Vector3(farLeft,   farTop,     -farDist));
		mWorldSpaceCorners[6] = eyeToWorld.transformAffine(Vector3(farLeft,   farBottom,  -farDist));
		mWorldSpaceCorners[7] = eyeToWorld.transformAffine(Vector3(farRight,  farBottom,  -farDist));


		mRecalcWorldSpaceCorners = false;
	}
    //-----------------------------------------------------------------------
    void Frustum::updateWorldSpaceCorners(void) const
    {
        updateView();

        if (mRecalcWorldSpaceCorners)
        {
			updateWorldSpaceCornersImpl();
        }

    }

    //-----------------------------------------------------------------------
    Real Frustum::getAspectRatio(void) const
    {
        return mAspect;
    }

    //-----------------------------------------------------------------------
    void Frustum::setAspectRatio(Real r)
    {
        mAspect = r;
        invalidateFrustum();
    }

    //-----------------------------------------------------------------------
    const AxisAlignedBox& Frustum::getBoundingBox(void) const
    {
        return mBoundingBox;
    }
    //-----------------------------------------------------------------------
    void Frustum::_updateRenderQueue(RenderQueue* queue)
    {
        // Add self 
        queue->addRenderable(this);
    }
    //-----------------------------------------------------------------------
    const String& Frustum::getMovableType(void) const
    {
        return msMovableType;
    }
    //-----------------------------------------------------------------------
	Real Frustum::getBoundingRadius(void) const
	{
        return (mFarDist == 0)? 100000 : mFarDist;
	}
    //-----------------------------------------------------------------------
    const MaterialPtr& Frustum::getMaterial(void) const
    {
        return mMaterial;
    }
    //-----------------------------------------------------------------------
    void Frustum::getRenderOperation(RenderOperation& op) 
    {
        updateVertexData();
        op.operationType = RenderOperation::OT_LINE_LIST;
        op.useIndexes = false;
        op.vertexData = &mVertexData;
    }
    //-----------------------------------------------------------------------
    void Frustum::getWorldTransforms(Matrix4* xform) const 
    {
        if (mParentNode)
            *xform = mParentNode->_getFullTransform();
        else
            *xform = Matrix4::IDENTITY;
    }
    //-----------------------------------------------------------------------
    const Quaternion& Frustum::getWorldOrientation(void) const 
    {
        if (mParentNode)
            return mParentNode->_getDerivedOrientation();
        else
            return Quaternion::IDENTITY;
    }
    //-----------------------------------------------------------------------
    const Vector3& Frustum::getWorldPosition(void) const 
    {
        if (mParentNode)
            return mParentNode->_getDerivedPosition();
        else
            return Vector3::ZERO;
    }
    //-----------------------------------------------------------------------
    Real Frustum::getSquaredViewDepth(const Camera* cam) const 
    {
        // Calc from centre
        if (mParentNode)
            return (cam->getDerivedPosition() 
                - mParentNode->_getDerivedPosition()).squaredLength();
        else
            return 0;
    }
    //-----------------------------------------------------------------------
    const LightList& Frustum::getLights(void) const 
    {
        // N/A
        static LightList ll;
        return ll;
    }
    //-----------------------------------------------------------------------
    void Frustum::_notifyCurrentCamera(Camera* cam)
    {
        // Make sure bounding box up-to-date
        updateFrustum();

        MovableObject::_notifyCurrentCamera(cam);
    }

    // -------------------------------------------------------------------
    void Frustum::invalidateFrustum() const
    {
        mRecalcFrustum = true;
        mRecalcFrustumPlanes = true;
        mRecalcWorldSpaceCorners = true;
        mRecalcVertexData = true;
    }
    // -------------------------------------------------------------------
    void Frustum::invalidateView() const
    {
        mRecalcView = true;
        mRecalcFrustumPlanes = true;
        mRecalcWorldSpaceCorners = true;
    }
    // -------------------------------------------------------------------
    const Vector3* Frustum::getWorldSpaceCorners(void) const
    {
        updateWorldSpaceCorners();

        return mWorldSpaceCorners;
    }
    //-----------------------------------------------------------------------
    void Frustum::setProjectionType(ProjectionType pt)
    {
        mProjType = pt;
        invalidateFrustum();
    }

    //-----------------------------------------------------------------------
    ProjectionType Frustum::getProjectionType(void) const
    {
        return mProjType;
    }
    //-----------------------------------------------------------------------
    const Vector3& Frustum::getPositionForViewUpdate(void) const
    {
        return mLastParentPosition;
    }
    //-----------------------------------------------------------------------
    const Quaternion& Frustum::getOrientationForViewUpdate(void) const
    {
        return mLastParentOrientation;
    }
    //-----------------------------------------------------------------------
    void Frustum::enableReflection(const Plane& p)
    {
        mReflect = true;
        mReflectPlane = p;
        mLinkedReflectPlane = 0;
        mReflectMatrix = Math::buildReflectionMatrix(p);
        invalidateView();

    }
    //-----------------------------------------------------------------------
    void Frustum::enableReflection(const MovablePlane* p)
    {
        mReflect = true;
        mLinkedReflectPlane = p;
        mReflectPlane = mLinkedReflectPlane->_getDerivedPlane();
        mReflectMatrix = Math::buildReflectionMatrix(mReflectPlane);
        mLastLinkedReflectionPlane = mLinkedReflectPlane->_getDerivedPlane();
        invalidateView();
    }
    //-----------------------------------------------------------------------
    void Frustum::disableReflection(void)
    {
        mReflect = false;
        mLinkedReflectPlane = 0;
        mLastLinkedReflectionPlane.normal = Vector3::ZERO;
        invalidateView();
    }
    //---------------------------------------------------------------------
    bool Frustum::projectSphere(const Sphere& sphere, 
        Real* left, Real* top, Real* right, Real* bottom) const
    {
		// See http://www.gamasutra.com/features/20021011/lengyel_06.htm
        // Transform light position into camera space

        updateView();
        Vector3 eyeSpacePos = mViewMatrix.transformAffine(sphere.getCenter());

		// initialise
		*left = *bottom = -1.0f;
		*right = *top = 1.0f;

        if (eyeSpacePos.z < 0)
        {
			updateFrustum();
			const Matrix4& projMatrix = getProjectionMatrix();
            Real r = sphere.getRadius();
			Real rsq = r * r;

            // early-exit
            if (eyeSpacePos.squaredLength() <= rsq)
                return false;

			Real Lxz = Math::Sqr(eyeSpacePos.x) + Math::Sqr(eyeSpacePos.z);
			Real Lyz = Math::Sqr(eyeSpacePos.y) + Math::Sqr(eyeSpacePos.z);

			// Find the tangent planes to the sphere
			// XZ first
			// calculate quadratic discriminant: b*b - 4ac
			// x = Nx
			// a = Lx^2 + Lz^2
			// b = -2rLx
			// c = r^2 - Lz^2
			Real a = Lxz;
			Real b = -2.0 * r * eyeSpacePos.x;
			Real c = rsq - Math::Sqr(eyeSpacePos.z);
			Real D = b*b - 4*a*c;

			// two roots?
			if (D > 0)
			{
				Real sqrootD = Math::Sqrt(D);
				// solve the quadratic to get the components of the normal
				Real Nx0 = (-b + sqrootD) / (2 * a);
				Real Nx1 = (-b - sqrootD) / (2 * a);
				
				// Derive Z from this
				Real Nz0 = (r - Nx0 * eyeSpacePos.x) / eyeSpacePos.z;
				Real Nz1 = (r - Nx1 * eyeSpacePos.x) / eyeSpacePos.z;

				// Get the point of tangency
				// Only consider points of tangency in front of the camera
				Real Pz0 = (Lxz - rsq) / (eyeSpacePos.z - ((Nz0 / Nx0) * eyeSpacePos.x));
				if (Pz0 < 0)
				{
					// Project point onto near plane in worldspace
					Real nearx0 = (Nz0 * mNearDist) / Nx0;
					// now we need to map this to viewport coords
					// use projection matrix since that will take into account all factors
					Vector3 relx0 = projMatrix * Vector3(nearx0, 0, -mNearDist);

					// find out whether this is a left side or right side
					Real Px0 = -(Pz0 * Nz0) / Nx0;
					if (Px0 > eyeSpacePos.x)
					{
						*right = std::min(*right, relx0.x);
					}
					else
					{
						*left = std::max(*left, relx0.x);
					}
				}
				Real Pz1 = (Lxz - rsq) / (eyeSpacePos.z - ((Nz1 / Nx1) * eyeSpacePos.x));
				if (Pz1 < 0)
				{
					// Project point onto near plane in worldspace
					Real nearx1 = (Nz1 * mNearDist) / Nx1;
					// now we need to map this to viewport coords
					// use projection matrix since that will take into account all factors
					Vector3 relx1 = projMatrix * Vector3(nearx1, 0, -mNearDist);

					// find out whether this is a left side or right side
					Real Px1 = -(Pz1 * Nz1) / Nx1;
					if (Px1 > eyeSpacePos.x)
					{
						*right = std::min(*right, relx1.x);
					}
					else
					{
						*left = std::max(*left, relx1.x);
					}
				}
			}


			// Now YZ 
			// calculate quadratic discriminant: b*b - 4ac
			// x = Ny
			// a = Ly^2 + Lz^2
			// b = -2rLy
			// c = r^2 - Lz^2
			a = Lyz;
			b = -2.0 * r * eyeSpacePos.y;
			c = rsq - Math::Sqr(eyeSpacePos.z);
			D = b*b - 4*a*c;

			// two roots?
			if (D > 0)
			{
				Real sqrootD = Math::Sqrt(D);
				// solve the quadratic to get the components of the normal
				Real Ny0 = (-b + sqrootD) / (2 * a);
				Real Ny1 = (-b - sqrootD) / (2 * a);

				// Derive Z from this
				Real Nz0 = (r - Ny0 * eyeSpacePos.y) / eyeSpacePos.z;
				Real Nz1 = (r - Ny1 * eyeSpacePos.y) / eyeSpacePos.z;

				// Get the point of tangency
				// Only consider points of tangency in front of the camera
				Real Pz0 = (Lyz - rsq) / (eyeSpacePos.z - ((Nz0 / Ny0) * eyeSpacePos.y));
				if (Pz0 < 0)
				{
					// Project point onto near plane in worldspace
					Real neary0 = (Nz0 * mNearDist) / Ny0;
					// now we need to map this to viewport coords
					// use projection matriy since that will take into account all factors
					Vector3 rely0 = projMatrix * Vector3(0, neary0, -mNearDist);

					// find out whether this is a top side or bottom side
					Real Py0 = -(Pz0 * Nz0) / Ny0;
					if (Py0 > eyeSpacePos.y)
					{
						*top = std::min(*top, rely0.y);
					}
					else
					{
						*bottom = std::max(*bottom, rely0.y);
					}
				}
				Real Pz1 = (Lyz - rsq) / (eyeSpacePos.z - ((Nz1 / Ny1) * eyeSpacePos.y));
				if (Pz1 < 0)
				{
					// Project point onto near plane in worldspace
					Real neary1 = (Nz1 * mNearDist) / Ny1;
					// now we need to map this to viewport coords
					// use projection matriy since that will take into account all factors
					Vector3 rely1 = projMatrix * Vector3(0, neary1, -mNearDist);

					// find out whether this is a top side or bottom side
					Real Py1 = -(Pz1 * Nz1) / Ny1;
					if (Py1 > eyeSpacePos.y)
					{
						*top = std::min(*top, rely1.y);
					}
					else
					{
						*bottom = std::max(*bottom, rely1.y);
					}
				}
			}
        }

        return (*left != -1.0f) || (*top != 1.0f) || (*right != 1.0f) || (*bottom != -1.0f);

    }
    //---------------------------------------------------------------------
    void Frustum::enableCustomNearClipPlane(const MovablePlane* plane)
    {
        mObliqueDepthProjection = true;
        mLinkedObliqueProjPlane = plane;
        mObliqueProjPlane = plane->_getDerivedPlane();
        invalidateFrustum();
    }
    //---------------------------------------------------------------------
    void Frustum::enableCustomNearClipPlane(const Plane& plane)
    {
        mObliqueDepthProjection = true;
        mLinkedObliqueProjPlane = 0;
        mObliqueProjPlane = plane;
        invalidateFrustum();
    }
    //---------------------------------------------------------------------
    void Frustum::disableCustomNearClipPlane(void)
    {
        mObliqueDepthProjection = false;
        mLinkedObliqueProjPlane = 0;
        invalidateFrustum();
    }
    //---------------------------------------------------------------------
	void Frustum::setCustomViewMatrix(bool enable, const Matrix4& viewMatrix)
	{
		mCustomViewMatrix = enable;
		if (enable)
		{
            assert(viewMatrix.isAffine());
			mViewMatrix = viewMatrix;
		}
		invalidateView();
	}
    //---------------------------------------------------------------------
	void Frustum::setCustomProjectionMatrix(bool enable, const Matrix4& projMatrix)
	{
		mCustomProjMatrix = enable;
		if (enable)
		{
			mProjMatrix = projMatrix;
		}
		invalidateFrustum();
	}



} // namespace Ogre
