shadow.h

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/*
    This file is part of Mitsuba, a physically based rendering system.

    Copyright (c) 2007-2014 by Wenzel Jakob and others.

    Mitsuba is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License Version 3
    as published by the Free Software Foundation.

    Mitsuba 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

#pragma once
#if !defined(__MITSUBA_HW_SHADOW_H_)
#define __MITSUBA_HW_SHADOW_H_

#include <mitsuba/hw/gpuprogram.h>

MTS_NAMESPACE_BEGIN

/** \brief Utility class for creating different kinds of shadow maps (cube,
 * directional, and paraboloid shadow maps) using hardware rasterization
 *
 * \ingroup libhw
 */
class MTS_EXPORT_HW ShadowMapGenerator : public Object {
public:
        enum EShadowMapType {
                /// Directional (orthographic) shadow map
                EDirectional = 0,

                /// Nonlinear paraboloid shadow map (captures one hemisphere)
                EParaboloid,

                /// Omnidirectional shadow map, 6 passes
                ECube,

                /// Omnidirectional shadow map, 1 pass with geometry shader
                ECubeSinglePass,

                /// Hemispherical cube shadow map, 5 passes
                EHemicube,

                /// Hemispherical cube shadow map, 1 pass with geometry shader
                EHemicubeSinglePass,

                /// Unused
                ETypeCount
        };

        /// Create a new shadow map generator
        ShadowMapGenerator(Renderer *renderer);

        /// Register the associated GPU programs
        void init();

        /**
         * \brief Allocate a texture that is suitable for storing
         * the requested type of shadow map and return it
         */
        ref<GPUTexture> allocate(Renderer *renderer,
                EShadowMapType type, int resolution);

        /**
         * \brief Render a shadow map using the desired technique
         *
         * \param renderer
         *    Underlying \ref Renderer instance
         * \param shadowMap
         *    Target texture, which was previously created using \ref allocate()
         * \param type
         *    Desired shadow map type
         * \param trafo
         *    View transformation of the source
         */
        void render(Renderer *renderer, GPUTexture *shadowMap, EShadowMapType type,
                const Transform &trafo, Float minDepth, Float maxDepth,
                const std::vector<Renderer::TransformedGPUGeometry> &geo);

        /**
         * \brief Convenience function for computing a transformation that
         * is suitable for creating a directional shadow map
         *
         * \param aabb
         *     Axis-aligned bounding box of the world-space content that
         *     should be covered
         *
         * \param d
         *     Viewing direction of the shadow map
         */
        Transform directionalFindGoodFrame(const AABB &aabb, const Vector &d) const;

        /// Release allocated resources
        void cleanup();

        /// Return the number of resident shaders
        size_t getShaderCount() const;

        MTS_DECLARE_CLASS()
protected:
        /// Virtual destructor
        virtual ~ShadowMapGenerator() { }
protected:
        ref<GPUProgram> m_program[ETypeCount];
        bool m_cubeDepthMapsSupported;

        /* Cached parameter indices (ECube) */
        int m_cubeTransform;
        int m_cubeProjDir;

        /* Cached parameter indices (ECubeSinglePass) */
        int m_cubeSinglePassTransform[6];
        int m_cubeSinglePassProjDir[6];

        /* Cached parameter indices (EHemicubeSinglePass) */
        int m_hemicubeSinglePassTransform[5];
        int m_hemicubeSinglePassProjDir[5];

        /* Cached parameter indices (EParaboloid) */
        int m_paraboloidMinDepth;
        int m_paraboloidInvDepthRange;
};

MTS_NAMESPACE_END

#endif /* __MITSUBA_HW_SHADOW_H_ */