magnum/src/Magnum/SceneGraph/AbstractCamera.h

#ifndef Magnum_SceneGraph_AbstractCamera_h
#define Magnum_SceneGraph_AbstractCamera_h
/*
    This file is part of Magnum.

    Copyright © 2010, 2011, 2012, 2013, 2014, 2015
              Vladimír Vondruš <mosra@centrum.cz>

    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
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    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.
*/

/** @file
 * @brief Class @ref Magnum::SceneGraph::AbstractCamera, enum @ref Magnum::SceneGraph::AspectRatioPolicy, alias @ref Magnum::SceneGraph::AbstractBasicCamera2D, @ref Magnum::SceneGraph::AbstractBasicCamera3D, typedef @ref Magnum::SceneGraph::AbstractCamera2D, @ref Magnum::SceneGraph::AbstractCamera3D
 */

#include "Magnum/Math/Functions.h"
#include "Magnum/Math/Matrix3.h"
#include "Magnum/Math/Matrix4.h"
#include "Magnum/SceneGraph/AbstractFeature.h"
#include "Magnum/SceneGraph/visibility.h"

namespace Magnum { namespace SceneGraph {

/**
@brief Camera aspect ratio policy

@see @ref AbstractCamera::setAspectRatioPolicy()
*/
enum class AspectRatioPolicy: UnsignedByte {
    NotPreserved,   /**< Don't preserve aspect ratio (default) */
    Extend,         /**< Extend on larger side of view */
    Clip            /**< Clip on smaller side of view */
};

namespace Implementation {
    template<UnsignedInt dimensions, class T> MatrixTypeFor<dimensions, T> aspectRatioFix(AspectRatioPolicy aspectRatioPolicy, const Math::Vector2<T>& projectionScale, const Vector2i& viewport);
}

/**
@brief Base for cameras

See Drawable documentation for more information. This class is not directly
instantiatable, use @ref BasicCamera2D or @ref BasicCamera3D subclasses
instead.

@anchor SceneGraph-AbstractCamera-explicit-specializations
## Explicit template specializations

The following specializations are explicitly compiled into @ref SceneGraph
library. For other specializations (e.g. using @ref Magnum::Double "Double"
type) you have to use @ref AbstractCamera.hpp implementation file to avoid
linker errors. See also relevant sections in @ref SceneGraph-Camera2D-explicit-specializations "Camera2D"
and @ref SceneGraph-Camera3D-explicit-specializations "Camera3D" class documentation or
@ref compilation-speedup-hpp for more information.

-   @ref AbstractCamera2D
-   @ref AbstractCamera3D

@see @ref scenegraph, @ref AbstractBasicCamera2D, @ref AbstractBasicCamera3D,
    @ref Drawable, @ref DrawableGroup
*/
template<UnsignedInt dimensions, class T> class AbstractCamera: public AbstractFeature<dimensions, T> {
    public:
        /** @brief Aspect ratio policy */
        AspectRatioPolicy aspectRatioPolicy() const { return _aspectRatioPolicy; }

        /**
         * @brief Set aspect ratio policy
         * @return Reference to self (for method chaining)
         */
        AbstractCamera<dimensions, T>& setAspectRatioPolicy(AspectRatioPolicy policy);

        /**
         * @brief Camera matrix
         *
         * Camera matrix describes world position relative to the camera and is
         * applied as first.
         */
        MatrixTypeFor<dimensions, T> cameraMatrix() {
            AbstractFeature<dimensions, T>::object().setClean();
            return _cameraMatrix;
        }

        /**
         * @brief Projection matrix
         *
         * Projection matrix handles e.g. perspective distortion and is applied
         * as last.
         * @see @ref projectionSize()
         */
        MatrixTypeFor<dimensions, T> projectionMatrix() const { return _projectionMatrix; }

        /**
         * @brief Size of (near) XY plane in current projection
         *
         * Returns size of near XY plane computed from projection matrix.
         * @see @ref projectionMatrix()
         */
        Math::Vector2<T> projectionSize() const {
            return {T(2.0)/_projectionMatrix[0].x(), T(2.0)/_projectionMatrix[1].y()};
        }

        /** @brief Viewport size */
        Vector2i viewport() const { return _viewport; }

        /**
         * @brief Set viewport size
         *
         * Stores viewport size internally and recalculates projection matrix
         * according to aspect ratio policy.
         * @see @ref setAspectRatioPolicy()
         */
        virtual void setViewport(const Vector2i& size);

        /**
         * @brief Draw
         *
         * Draws given group of drawables.
         */
        virtual void draw(DrawableGroup<dimensions, T>& group);

    protected:
        /**
         * @brief Constructor
         * @param object        Object holding the camera
         */
        explicit AbstractCamera(AbstractObject<dimensions, T>& object);

        ~AbstractCamera();

        /** Recalculates camera matrix */
        void cleanInverted(const MatrixTypeFor<dimensions, T>& invertedAbsoluteTransformationMatrix) override {
            _cameraMatrix = invertedAbsoluteTransformationMatrix;
        }

        #ifndef DOXYGEN_GENERATING_OUTPUT
        void fixAspectRatio() {
            _projectionMatrix = Implementation::aspectRatioFix<dimensions, T>(_aspectRatioPolicy, {Math::abs(rawProjectionMatrix[0].x()), Math::abs(rawProjectionMatrix[1].y())}, _viewport)*rawProjectionMatrix;
        }

        MatrixTypeFor<dimensions, T> rawProjectionMatrix;
        AspectRatioPolicy _aspectRatioPolicy;
        #endif

    private:
        MatrixTypeFor<dimensions, T> _projectionMatrix;
        MatrixTypeFor<dimensions, T> _cameraMatrix;

        Vector2i _viewport;
};

/**
@brief Base camera for two-dimensional scenes

Convenience alternative to `AbstractCamera<2, T>`. See
@ref AbstractCamera for more information.
@see @ref AbstractCamera2D, @ref AbstractBasicCamera3D
*/
template<class T> using AbstractBasicCamera2D = AbstractCamera<2, T>;

/**
@brief Base camera for two-dimensional float scenes

@see @ref AbstractCamera3D
*/
typedef AbstractBasicCamera2D<Float> AbstractCamera2D;

/**
@brief Base camera for three-dimensional scenes

Convenience alternative to `AbstractCamera<3, T>`. See
@ref AbstractCamera for more information.
@see @ref AbstractCamera3D, @ref AbstractBasicCamera2D
*/
template<class T> using AbstractBasicCamera3D = AbstractCamera<3, T>;

/**
@brief Base camera for three-dimensional float scenes

@see @ref AbstractCamera2D
*/
typedef AbstractBasicCamera3D<Float> AbstractCamera3D;

#if defined(CORRADE_TARGET_WINDOWS) && !defined(__MINGW32__)
extern template class MAGNUM_SCENEGRAPH_EXPORT AbstractCamera<2, Float>;
extern template class MAGNUM_SCENEGRAPH_EXPORT AbstractCamera<3, Float>;
#endif

}}

#endif