/*

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

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.

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*/

#ifndef __ShadowCameraSetup_H__

#define __ShadowCameraSetup_H__

#include "OgrePrerequisites.h"

#include "OgreHeaderPrefix.h"

namespace Ogre {

    /** \addtogroup Core

    *  @{

    */

    /** \addtogroup Scene

    *  @{

    */

    /** This class allows you to plug in new ways to define the camera setup when

        rendering and projecting shadow textures.

        The default projection used when rendering shadow textures is a uniform

        frustum. This is pretty straight forward but doesn't make the best use of 

        the space in the shadow map since texels closer to the camera will be larger, 

        resulting in 'jaggies'. There are several ways to distribute the texels

        in the shadow texture differently, and this class allows you to override

        that. 

    @par

        Ogre is provided with several alternative shadow camera setups, including

        LiSPSM (LiSPSMShadowCameraSetup) and Plane Optimal (PlaneOptimalShadowCameraSetup).

        Others can of course be written to incorporate other algorithms. All you 

        have to do is instantiate one of these classes and enable it using 

        SceneManager::setShadowCameraSetup (global) or Light::setCustomShadowCameraSetup

        (per light). In both cases the instance is wrapped in a SharedPtr which means

        it will  be deleted automatically when no more references to it exist.

    @note

        Shadow map matrices, being projective matrices, have 15 degrees of freedom.

        3 of these degrees of freedom are fixed by the light's position.  4 are used to

        affinely affect z values.  6 affinely affect u,v sampling.  2 are projective

        degrees of freedom.  This class is meant to allow custom methods for 

        handling optimization.

    */

    class _OgreExport ShadowCameraSetup : public ShadowDataAlloc

    {

    public:

        /// Function to implement -- must set the shadow camera properties

        virtual void getShadowCamera (const SceneManager *sm, const Camera *cam, 

                                      const Viewport *vp, const Light *light, Camera *texCam, size_t iteration) const = 0;

        /// Need virtual destructor in case subclasses use it

        virtual ~ShadowCameraSetup() {}

    };

    /** Implements default shadow camera setup

        This implements the default shadow camera setup algorithm.  This is what might

        be referred to as "normal" shadow mapping.

    */

    class _OgreExport DefaultShadowCameraSetup : public ShadowCameraSetup

    {

    public:

        DefaultShadowCameraSetup();

        virtual ~DefaultShadowCameraSetup();

        static ShadowCameraSetupPtr create()

        {

            return std::make_shared<DefaultShadowCameraSetup>();

        }

        /// Default shadow camera setup

        void getShadowCamera (const SceneManager *sm, const Camera *cam,

                                      const Viewport *vp, const Light *light, Camera *texCam, size_t iteration) const override;

    };

    /** @} */

    /** @} */

}

#include "OgreHeaderSuffix.h"

#endif