source: downloads/OgreMain/include/OgreShadowCameraSetup.h @ 5

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

Copyright (c) 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.
-----------------------------------------------------------------------------
*/
#ifndef __ShadowCameraSetup_H__
#define __ShadowCameraSetup_H__

#include "OgrePrerequisites.h"
#include "OgreMovablePlane.h"
#include "OgreSharedPtr.h"


namespace Ogre {

    /** This class allows you to plug in new ways to define the camera setup when
                rendering and projecting shadow textures.
        @remarks
                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:
                /// 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) const = 0;
                /// Need virtual destructor in case subclasses use it
                virtual ~ShadowCameraSetup() {}

        };



        /** Implements default shadow camera setup
        @remarks
            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:
                /// Default constructor
                DefaultShadowCameraSetup();
                /// Destructor
                virtual ~DefaultShadowCameraSetup();

                /// Default shadow camera setup
                virtual void getShadowCamera (const SceneManager *sm, const Camera *cam, 
                                                                          const Viewport *vp, const Light *light, Camera *texCam) const;
        };



        typedef SharedPtr<ShadowCameraSetup> ShadowCameraSetupPtr;

}

#endif