edgedetectionmodifier.h

// © Copyright 2010 - 2016 BlackTopp Studios Inc.
/* This file is part of The Mezzanine Engine.

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/*
 -----------------------------------------------------------------------------
 This source file is part of ogre-procedural

 For the latest info, see http://code.google.com/p/ogre-procedural/

 Copyright (c) 2010-2013 Michael Broutin

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
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 */
#ifndef _graphicsproceduraledgedetectionmodifier_h
#define _graphicsproceduraledgedetectionmodifier_h

#include "Graphics/Procedural/Texture/texturemodifier.h"

#include "vector3.h"

namespace Mezzanine
{
    namespace Graphics
    {
        namespace Procedural
        {
            ///////////////////////////////////////////////////////////////////////////////
            /// @brief A modifier that will reduce the texture to an outline of the detected edges in the texture.
            /// @details
            ///////////////////////////////////////
            class MEZZ_LIB EdgeDetectionModifier : public TextureModifier
            {
            public:
                /// @brief An enum describing which algorithm to use for edge detection.
                enum DetectionMode
                {
                    DM_Homogenity     = 1,   ///< Detect edges based on difference in colour between the pixel being processed and all surrounding pixels.
                    DM_Difference     = 2,   ///< Detect edges based on difference in colour between opposite surrounding pixels.
                    DM_Sobel          = 3,   ///< Use the Sobel Operator algorithm to detect edges.
                    DM_Canny          = 4    ///< Use the Canny multi-stage algorthm to detect edges.
                };

                /// @brief Convenience typedef for an array of Vector3's.
                typedef std::vector<Vector3> VectorContainer;
                /// @brief Convenience typedef for returning a 3x3 matrix of Vector3's containing colour data.
                typedef VectorContainer VectorBlock;
            protected:
                /// @internal
                /// @brief The algorithm to use to detect edges.
                DetectionMode EdgeDetect;
                /// @internal
                /// @brief The lowest value for each colour channel that will be considered valid.
                UInt8 LowerThreshold;
                /// @internal
                /// @brief The highest value for each colour channel that will be considered valid.
                UInt8 UpperThreshold;
                /// @internal
                /// @brief The sigma to set for the blur step of the Canny filter.
                UInt8 EdgeDetectionSigma;

                /// @internal
                /// @brief Detect edges in the provided texture by processing all surrounding pixels.
                /// @param Buffer The texture buffer to be rendered to.
                void ProcessHomogenity(TextureBuffer& Buffer);
                /// @internal
                /// @brief Detect edges in the provided texture by processing pixels above and below the current pixel.
                /// @param Buffer The texture buffer to be rendered to.
                void ProcessDifference(TextureBuffer& Buffer);
                /// @internal
                /// @brief Detect edges using the Sobel Operator.
                /// @param Buffer The texture buffer to be rendered to.
                void ProcessSobel(TextureBuffer& Buffer);
                /// @internal
                /// @brief Detect edges using the Canny multi-stage algorithm.
                /// @param Buffer The texture buffer to be rendered to.
                void ProcessCanny(TextureBuffer& Buffer);
                /// @internal
                /// @brief Gets the colours of the specified pixel and all surrounding pixels.
                /// @param X The X coordinate of the center pixel to retrieve.
                /// @param Y The Y coordinate of the center pixel to retrieve.
                /// @param Buffer The texture buffer to retrieve pixel data from.
                /// @return Returns a pointer to an array of Vector3's that are the colours of the current and surrounding pixels.
                VectorBlock GetBlock(const Integer X, const Integer Y, TextureBuffer& Buffer) const;
            public:
                /// @brief Blank constructor.
                EdgeDetectionModifier();
                /// @brief Class destructor.
                virtual ~EdgeDetectionModifier();

                ///////////////////////////////////////////////////////////////////////////////
                // Utility

                /// @copydoc TextureModifier::Modify(TextureBuffer&)
                virtual void Modify(TextureBuffer& Buffer);
                /// @copydoc TextureModifier::GetName() const
                virtual String GetName() const;

                ///////////////////////////////////////////////////////////////////////////////
                // Configuration

                /// @brief Sets the detection algorith to use for detecting edges.
                /// @param Mode The detection algorith to use.
                /// @return Returns a reference to this.
                EdgeDetectionModifier& SetDetectionType(const DetectionMode Mode);
                /// @brief Sets the lower threshold for the Canny filter.
                /// @remarks This variable is only used if DM_Canny is set as the detection method.
                /// @param Low The lowest value for each colour channel that will be considered valid.
                /// @return Returns a reference to this.
                EdgeDetectionModifier& SetLowerThreshold(const UInt8 Low);
                /// @brief Sets the upper threshold for the Canny filter.
                /// @remarks This variable is only used if DM_Canny is set as the detection method.
                /// @param High The highest value for each colour channel that will be considered valid.
                /// @return Returns a reference to this.
                EdgeDetectionModifier& SetUpperThreshold(const UInt8 High);
                /// @brief Sets the sigma for the blur stage of the Canny filter.
                /// @remarks This variable is only used if DM_Canny is set as the detection method.
                /// @param Sigma The sigma to set for the blur step of the Canny filter.
                /// @return Returns a reference to this.
                EdgeDetectionModifier& SetEdgeDetectionSigma(const UInt8 Sigma);
            };//EdgeDetectionModifier
        }//Procedural
    }//Graphics
}//Mezzanine

#endif