/*

-----------------------------------------------------------------------------

This source file is part of OGRE

    (Object-oriented Graphics Rendering Engine)

For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2014 Torus Knot Software Ltd

Permission is hereby granted, free of charge, to any person obtaining a copy

of this software and associated documentation files (the "Software"), to deal

in the Software without restriction, including without limitation the rights

to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

copies of the Software, and to permit persons to whom the Software is

furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in

all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

THE SOFTWARE.

-----------------------------------------------------------------------------

*/

#ifndef __Frustum_H__

#define __Frustum_H__

#include "OgrePrerequisites.h"

#include "OgreMovableObject.h"

#include "OgreAxisAlignedBox.h"

#include "OgreVertexIndexData.h"

#include "OgreHeaderPrefix.h"

namespace Ogre

{

    /** \addtogroup Core

    *  @{

    */

    /** \addtogroup Scene

    *  @{

    */

    /** Specifies perspective (realistic) or orthographic (architectural) projection.

    */

    enum ProjectionType : uint8

    {

        PT_ORTHOGRAPHIC,

        PT_PERSPECTIVE

    };

    /** Worldspace clipping planes.

    */

    enum FrustumPlane : uint8

    {

        FRUSTUM_PLANE_NEAR   = 0,

        FRUSTUM_PLANE_FAR    = 1,

        FRUSTUM_PLANE_LEFT   = 2,

        FRUSTUM_PLANE_RIGHT  = 3,

        FRUSTUM_PLANE_TOP    = 4,

        FRUSTUM_PLANE_BOTTOM = 5

    };

    /** A frustum represents a pyramid, capped at the near and far end which is

        used to represent either a visible area or a projection area. Can be used

        for a number of applications.

    */

    class _OgreExport Frustum : public MovableObject

    {

    protected:

        /// y-direction field-of-view (default 45)

        Radian mFOVy;

        /// Far clip distance - default 10000

        float mFarDist;

        /// Near clip distance - default 100

        float mNearDist;

        /// x/y viewport ratio - default 1.3333

        Real mAspect;

        /// Ortho height size (world units)

        Real mOrthoHeight;

        /// Off-axis frustum center offset - default (0.0, 0.0)

        Vector2 mFrustumOffset;

        /// Focal length of frustum (for stereo rendering, defaults to 1.0)

        Real mFocalLength;

        /// The 6 main clipping planes

        mutable Plane mFrustumPlanes[6];

        /// Stored versions of parent orientation / position

        mutable Quaternion mLastParentOrientation;

        mutable Vector3 mLastParentPosition;

        /// Pre-calced standard projection matrix but with render system depth range

        mutable Matrix4 mProjMatrixRSDepth;

        /// Pre-calced standard projection matrix

        mutable Matrix4 mProjMatrix;

        /// Pre-calced view matrix

        mutable Affine3 mViewMatrix;

        /// Something's changed in the frustum shape?

        mutable bool mRecalcFrustum;

        /// Something re the view pos has changed

        mutable bool mRecalcView;

        /// Something re the frustum planes has changed

        mutable bool mRecalcFrustumPlanes;

        /// Something re the world space corners has changed

        mutable bool mRecalcWorldSpaceCorners;

        /// Are we using a custom view matrix?

        bool mCustomViewMatrix;

        /// Are we using a custom projection matrix?

        bool mCustomProjMatrix;

        /// Have the frustum extents been manually set?

        bool mFrustumExtentsManuallySet;

        /// Orthographic or perspective?

        ProjectionType mProjType;

        /// Frustum extents

        mutable RealRect mExtents;

        // Internal functions for calcs

        RealRect calcProjectionParameters() const;

        /// Update frustum if out of date

        void updateFrustum(void) const;

        /// Update view if out of date

        void updateView(void) const;

        /// Implementation of updateFrustum (called if out of date)

        virtual void updateFrustumImpl(void) const;

        /// Implementation of updateView (called if out of date)

        virtual void updateViewImpl(void) const;

        void updateFrustumPlanes(void) const;

        /// Implementation of updateFrustumPlanes (called if out of date)

        virtual void updateFrustumPlanesImpl(void) const;

        void updateWorldSpaceCorners(void) const;

        /// Implementation of updateWorldSpaceCorners (called if out of date)

        virtual void updateWorldSpaceCornersImpl(void) const;

        virtual bool isViewOutOfDate(void) const;

        bool isFrustumOutOfDate(void) const;

        /// Signal to update frustum information.

        virtual void invalidateFrustum(void) const;

        /// Signal to update view information.

        virtual void invalidateView(void) const;

        ColourValue mDebugColour;

        /// Pointer to a reflection plane (automatically updated)

        const MovablePlane* mLinkedReflectPlane;

        /// Pointer to oblique projection plane (automatically updated)

        const MovablePlane* mLinkedObliqueProjPlane;

        mutable AxisAlignedBox mBoundingBox;

        mutable Vector3 mWorldSpaceCorners[8];

        /// Derived reflection matrix

        mutable Affine3 mReflectMatrix;

        /// Fixed reflection plane

        mutable Plane mReflectPlane;

        /// Record of the last world-space reflection plane info used

        mutable Plane mLastLinkedReflectionPlane;

        /// Fixed oblique projection plane

        mutable Plane mObliqueProjPlane;

        /// Record of the last world-space oblique depth projection plane info used

        mutable Plane mLastLinkedObliqueProjPlane;

        /// Is this frustum to act as a reflection of itself?

        bool mReflect;

        /// Is this frustum using an oblique depth projection?

        bool mObliqueDepthProjection;

    public:

        /// Named constructor

        Frustum(const String& name = BLANKSTRING);

        virtual ~Frustum();

        /** Sets the Y-dimension Field Of View (FOV) of the frustum.

            Field Of View (FOV) is the angle made between the frustum's position, and the edges

            of the 'screen' onto which the scene is projected. High values (90+ degrees) result in a wide-angle,

            fish-eye kind of view, low values (30- degrees) in a stretched, telescopic kind of view. Typical values

            are between 45 and 60 degrees.

        @par

            This value represents the VERTICAL field-of-view. The horizontal field of view is calculated from

            this depending on the dimensions of the viewport (they will only be the same if the viewport is square).

         */

        void setFOVy(const Radian& fovy);

        /** Retrieves the frustums Y-dimension Field Of View (FOV).

        */

        const Radian& getFOVy(void) const;

        /** Sets the position of the near clipping plane.

            The position of the near clipping plane is the distance from the frustums position to the screen

            on which the world is projected. The near plane distance, combined with the field-of-view and the

            aspect ratio, determines the size of the viewport through which the world is viewed (in world

            coordinates). Note that this world viewport is different to a screen viewport, which has it's

            dimensions expressed in pixels. The frustums viewport should have the same aspect ratio as the

            screen viewport it renders into to avoid distortion.

        @param nearDist

            The distance to the near clipping plane from the frustum in world coordinates.

         */

        void setNearClipDistance(float nearDist);

        /** Retrieves the distance from the frustum to the near clipping plane.

        */

        virtual float getNearClipDistance(void) const { return mNearDist; }

        /** Sets the distance to the far clipping plane.

            The view frustum is a pyramid created from the frustum position and the edges of the viewport.

            This method sets the distance for the far end of that pyramid. 

            Different applications need different values: e.g. a flight sim

            needs a much further far clipping plane than a first-person 

            shooter. An important point here is that the larger the ratio 

            between near and far clipping planes, the lower the accuracy of

            the Z-buffer used to depth-cue pixels. This is because the

            Z-range is limited to the size of the Z buffer (16 or 32-bit) 

            and the max values must be spread over the gap between near and

            far clip planes. As it happens, you can affect the accuracy far 

            more by altering the near distance rather than the far distance, 

            but keep this in mind.

        @param farDist

            The distance to the far clipping plane from the frustum in 

            world coordinates.If you specify 0, this means an infinite view

            distance which is useful especially when projecting shadows; but

            be careful not to use a near distance too close.

        */

        void setFarClipDistance(float farDist);

        /** Retrieves the distance from the frustum to the far clipping plane.

        */

        virtual float getFarClipDistance(void) const { return mFarDist; }

        /** Sets the aspect ratio for the frustum viewport.

            The ratio between the x and y dimensions of the rectangular area visible through the frustum

            is known as aspect ratio: aspect = width / height .

        @par

            The default for most fullscreen windows is 1.3333 - this is also assumed by Ogre unless you

            use this method to state otherwise.

        */

        void setAspectRatio(Real ratio);

        /** Retrieves the current aspect ratio.

        */

        Real getAspectRatio(void) const;

        /** Sets frustum offsets, used in stereo rendering.

            You can set both horizontal and vertical plane offsets of "eye"; in

            stereo rendering frustum is moved in horizontal plane. To be able to

            render from two "eyes" you'll need two cameras rendering on two

            RenderTargets.

        @par

            The frustum offsets is in world coordinates, and default to (0, 0) - no offsets.

        @param offset

            The horizontal and vertical plane offsets.

        */

        void setFrustumOffset(const Vector2& offset);

        /** Sets frustum offsets, used in stereo rendering.

            You can set both horizontal and vertical plane offsets of "eye"; in

            stereo rendering frustum is moved in horizontal plane. To be able to

            render from two "eyes" you'll need two cameras rendering on two

            RenderTargets.

        @par

            The frustum offsets is in world coordinates, and default to (0, 0) - no offsets.

        @param horizontal

            The horizontal plane offset.

        @param vertical

            The vertical plane offset.

        */

        void setFrustumOffset(Real horizontal = 0.0, Real vertical = 0.0);

        /** Retrieves the frustum offsets.

        */

        const Vector2& getFrustumOffset() const;

        /** Sets frustum focal length (used in stereo rendering).

        @param focalLength

            The distance to the focal plane from the frustum in world coordinates.

        */

        void setFocalLength(Real focalLength = 1.0);

        /** Returns focal length of frustum.

        */

        Real getFocalLength() const;

        /** Manually set the extents of the frustum.

        @param left, right, top, bottom The position where the side clip planes intersect

            the near clip plane, in eye space

        */

        void setFrustumExtents(Real left, Real right, Real top, Real bottom);

        /** Reset the frustum extents to be automatically derived from other params. */

        void resetFrustumExtents();

        /** Get the extents of the frustum in view space. */

        RealRect getFrustumExtents() const;

        /** Gets the depth-adjusted projection matrix for the current rendersystem

            This differs from the rendering-API independent @ref getProjectionMatrix

            in that it the resulting depth range may vary between render systems since D3D uses [0,1] and

            GL uses [-1,1]. This is required for vertex and fragment programs.

        */

        const Matrix4& getProjectionMatrixWithRSDepth(void) const;

        /** Gets the normal projection matrix for this frustum

            i.e. the projection matrix which conforms to standard right-handed rules and

            uses depth range [-1,+1]. This is required for some uniform algebra.

        */

        const Matrix4& getProjectionMatrix(void) const;

        /** Gets the view matrix for this frustum. Mainly for use by OGRE internally.

        */

        virtual const Affine3& getViewMatrix(void) const;

        /** Calculate a view matrix for this frustum, relative to a potentially dynamic point. 

            Mainly for use by OGRE internally when using camera-relative rendering

            for frustums that are not the centre (e.g. texture projection)

        */

        void calcViewMatrixRelative(const Vector3& relPos, Matrix4& matToUpdate) const;

        /** Set whether to use a custom view matrix on this frustum.

            This is an advanced method which allows you to manually set

            the view matrix on this frustum, rather than having it calculate

            itself based on it's position and orientation. 

        @note

            After enabling a custom view matrix, the frustum will no longer

            update on its own based on position / orientation changes. You 

            are completely responsible for keeping the view matrix up to date.

            The custom matrix will be returned from getViewMatrix.

        @param enable If @c true, the custom view matrix passed as the second 

            parameter will be used in preference to an auto calculated one. If

            false, the frustum will revert to auto calculating the view matrix.

        @param viewMatrix The custom view matrix to use

        @see Frustum::setCustomProjectionMatrix

        */

        void setCustomViewMatrix(bool enable, const Affine3& viewMatrix = Affine3::IDENTITY);

        /// Returns whether a custom view matrix is in use

        bool isCustomViewMatrixEnabled(void) const { return mCustomViewMatrix; }

        /** Set whether to use a custom projection matrix on this frustum.

            This is an advanced method which allows you to manually set

            the projection matrix on this frustum, rather than having it 

            calculate itself based on it's position and orientation. 

        @note

            After enabling a custom projection matrix, the frustum will no 

            longer update on its own based on field of view and near / far

            distance changes. You are completely responsible for keeping the 

            projection matrix up to date if those values change. The custom 

            matrix will be returned from getProjectionMatrix and derivative

            functions.

        @param enable

            If @c true, the custom projection matrix passed as the 

            second parameter will be used in preference to an auto calculated 

            one. If @c false, the frustum will revert to auto calculating the 

            projection matrix.

        @param projectionMatrix

            The custom view matrix to use.

        @see Frustum::setCustomViewMatrix

        */

        void setCustomProjectionMatrix(bool enable,

                                       const Matrix4& projectionMatrix = Matrix4::IDENTITY);

        /// Returns whether a custom projection matrix is in use

        bool isCustomProjectionMatrixEnabled(void) const { return mCustomProjMatrix; }

        /** Retrieves the clipping planes of the frustum (world space).

            The clipping planes are ordered as declared in enumerate constants FrustumPlane.

        */

        virtual const Plane* getFrustumPlanes(void) const;

        /** Retrieves a specified plane of the frustum (world space).

            Gets a reference to one of the planes which make up the frustum frustum, e.g. for clipping purposes.

        */

        virtual const Plane& getFrustumPlane( unsigned short plane ) const;

        /// @copydoc MovableObject::isVisible

        using Ogre::MovableObject::isVisible;

        /** Tests whether the given container is visible in the Frustum.

        @param bound

            Bounding box to be checked (world space).

        @param culledBy

            Optional pointer to an int which will be filled by the plane number which culled

            the box if the result was @c false;

        @return

            If the box was visible, @c true is returned.

        @par

            Otherwise, @c false is returned.

        */

        virtual bool isVisible(const AxisAlignedBox& bound, FrustumPlane* culledBy = 0) const;

        /** Tests whether the given container is visible in the Frustum.

        @param bound

            Bounding sphere to be checked (world space).

        @param culledBy

            Optional pointer to an int which will be filled by the plane number which culled

            the box if the result was @c false;

        @return

            If the sphere was visible, @c true is returned.

        @par

            Otherwise, @c false is returned.

        */

        virtual bool isVisible(const Sphere& bound, FrustumPlane* culledBy = 0) const;

        /** Tests whether the given vertex is visible in the Frustum.

        @param vert

            Vertex to be checked (world space).

        @param culledBy

            Optional pointer to an int which will be filled by the plane number which culled

            the box if the result was @c false;

        @return

            If the sphere was visible, @c true is returned.

        @par

            Otherwise, @c false is returned.

        */

        virtual bool isVisible(const Vector3& vert, FrustumPlane* culledBy = 0) const;

        uint32 getTypeFlags(void) const override;

        const AxisAlignedBox& getBoundingBox(void) const override;

        Real getBoundingRadius(void) const override;

        void _updateRenderQueue(RenderQueue* queue) override;

        const String& getMovableType(void) const override;

        void _notifyCurrentCamera(Camera* cam) override;

        void setDebugColour(const ColourValue& col) { mDebugColour = col; }

        const ColourValue& getDebugColour() const { return mDebugColour; }

        typedef Vector3 Corners[8];

        /** Gets the world space corners of the frustum.

            The corners are ordered as follows: top-right near, 

            top-left near, bottom-left near, bottom-right near, 

            top-right far, top-left far, bottom-left far, bottom-right far.

        */

        virtual const Corners& getWorldSpaceCorners(void) const;

        /** Sets the type of projection to use (orthographic or perspective). Default is perspective.

        */

        virtual void setProjectionType(ProjectionType pt);

        /** Retrieves info on the type of projection used (orthographic or perspective).

        */

        ProjectionType getProjectionType(void) const;

        /** Sets the orthographic window settings, for use with orthographic rendering only. 

        @note Calling this method will recalculate the aspect ratio, use 

            setOrthoWindowHeight or setOrthoWindowWidth alone if you wish to 

            preserve the aspect ratio but just fit one or other dimension to a 

            particular size.

        @param w

            The width of the view window in world units.

        @param h

            The height of the view window in world units.

        */

        void setOrthoWindow(Real w, Real h);

        /** Sets the orthographic window height, for use with orthographic rendering only. 

        @note The width of the window will be calculated from the aspect ratio. 

        @param h

            The height of the view window in world units.

        */

        void setOrthoWindowHeight(Real h);

        /** Sets the orthographic window width, for use with orthographic rendering only. 

        @note The height of the window will be calculated from the aspect ratio. 

        @param w

            The width of the view window in world units.

        */

        void setOrthoWindowWidth(Real w);

        /** Gets the orthographic window height, for use with orthographic rendering only. 

        */

        Real getOrthoWindowHeight() const;

        /** Gets the orthographic window width, for use with orthographic rendering only. 

        @note This is calculated from the orthographic height and the aspect ratio

        */

        Real getOrthoWindowWidth() const;

        /** Modifies this frustum so it always renders from the reflection of itself through the

            plane specified.

            This is obviously useful for performing planar reflections. 

        */

        void enableReflection(const Plane& p);

        /** Modifies this frustum so it always renders from the reflection of itself through the

            plane specified. Note that this version of the method links to a plane

            so that changes to it are picked up automatically. It is important that

            this plane continues to exist whilst this object does; do not destroy

            the plane before the frustum.

            This is obviously useful for performing planar reflections. 

        */

        void enableReflection(const MovablePlane* p);

        /** Disables reflection modification previously turned on with enableReflection */

        void disableReflection(void);

        /// Returns whether this frustum is being reflected

        bool isReflected(void) const { return mReflect; }

        /// Returns the reflection matrix of the frustum if appropriate

        const Affine3& getReflectionMatrix(void) const { return mReflectMatrix; }

        /// Returns the reflection plane of the frustum if appropriate

        const Plane& getReflectionPlane(void) const { return mReflectPlane; }

        /** Project a sphere onto the near plane and get the bounding rectangle. 

        @param sphere The world-space sphere to project.

        @param left

            Pointers to destination values, these will be completed with 

            the normalised device coordinates (in the range {-1,1}).

        @param top

            Pointers to destination values, these will be completed with 

            the normalised device coordinates (in the range {-1,1}).

        @param right

            Pointers to destination values, these will be completed with 

            the normalised device coordinates (in the range {-1,1}).

        @param bottom

            Pointers to destination values, these will be completed with 

            the normalised device coordinates (in the range {-1,1}).

        @return @c true if the sphere was projected to a subset of the near plane,

            @c false if the entire near plane was contained.

        */

        virtual bool projectSphere(const Sphere& sphere, 

            Real* left, Real* top, Real* right, Real* bottom) const;

        /** Links the frustum to a custom near clip plane, which can be used

            to clip geometry in a custom manner without using user clip planes.

            There are several applications for clipping a scene arbitrarily by

            a single plane; the most common is when rendering a reflection to 

            a texture, and you only want to render geometry that is above the 

            water plane (to do otherwise results in artefacts). Whilst it is

            possible to use user clip planes, they are not supported on all

            cards, and sometimes are not hardware accelerated when they are

            available. Instead, where a single clip plane is involved, this

            technique uses a 'fudging' of the near clip plane, which is 

            available and fast on all hardware, to perform as the arbitrary

            clip plane. This does change the shape of the frustum, leading 

            to some depth buffer loss of precision, but for many of the uses of

            this technique that is not an issue.

        @par 

            This version of the method links to a plane, rather than requiring

            a by-value plane definition, and therefore you can 

            make changes to the plane (e.g. by moving / rotating the node it is

            attached to) and they will automatically affect this object.

        @note This technique only works for perspective projection.

        @param plane

            The plane to link to to perform the clipping. This plane

            must continue to exist while the camera is linked to it; do not

            destroy it before the frustum. 

        */

        void enableCustomNearClipPlane(const MovablePlane* plane);

        /** Links the frustum to a custom near clip plane, which can be used

            to clip geometry in a custom manner without using user clip planes.

            There are several applications for clipping a scene arbitrarily by

            a single plane; the most common is when rendering a reflection to  

            a texture, and you only want to render geometry that is above the 

            water plane (to do otherwise results in artefacts). Whilst it is

            possible to use user clip planes, they are not supported on all

            cards, and sometimes are not hardware accelerated when they are

            available. Instead, where a single clip plane is involved, this

            technique uses a 'fudging' of the near clip plane, which is 

            available and fast on all hardware, to perform as the arbitrary

            clip plane. This does change the shape of the frustum, leading 

            to some depth buffer loss of precision, but for many of the uses of

            this technique that is not an issue.

        @note This technique only works for perspective projection.

        @param plane

            The plane to link to to perform the clipping. This plane

            must continue to exist while the camera is linked to it; do not

            destroy it before the frustum. 

        */

        void enableCustomNearClipPlane(const Plane& plane);

        /** Disables any custom near clip plane. */

        void disableCustomNearClipPlane(void);

        /** Is a custom near clip plane in use? */

        bool isCustomNearClipPlaneEnabled(void) const

        { return mObliqueDepthProjection; }

        /// @copydoc MovableObject::visitRenderables

        void visitRenderables(Renderable::Visitor* visitor, 

            bool debugRenderables = false) override;

        /// Small constant used to reduce far plane projection to avoid inaccuracies

        static const Real INFINITE_FAR_PLANE_ADJUST;

        /** Get the derived position of this frustum. */

        virtual const Vector3& getPositionForViewUpdate(void) const;

        /** Get the derived orientation of this frustum. */

        virtual const Quaternion& getOrientationForViewUpdate(void) const;

        /** Gets a world-space list of planes enclosing the frustum.

        */

        PlaneBoundedVolume getPlaneBoundedVolume();

    };

    /** @} */

    /** @} */

} // namespace Ogre

#include "OgreHeaderSuffix.h"

#endif // __Frustum_H__