axmol/cocos/3d/CCTerrain.h

/****************************************************************************
Copyright (c) 2015 Chukong Technologies Inc.

http://www.cocos2d-x.org

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THE SOFTWARE.
****************************************************************************/
#ifndef CC_TERRAIN_H
#define CC_TERRAIN_H

#include <vector>

#include "2d/CCNode.h"
#include "2d/CCCamera.h"
#include "renderer/CCTexture2D.h"
#include "renderer/CCCustomCommand.h"
#include "renderer/CCRenderState.h"
#include "3d/CCAABB.h"
#include "3d/CCRay.h"
#include "base/CCEventListenerCustom.h"
#include "base/CCEventDispatcher.h"

NS_CC_BEGIN

/**
 * @addtogroup _3d
 * @{
 */

 /**
 * the maximum amount of the chunkes
 **/
#define MAX_CHUNKES 256

  /**
    * Terrain
    * Defines a Terrain that is capable of rendering large landscapes from 2D heightmap images.
    * Terrains can be constructed from several different internal formats heightmap sources:
    *  1. RGB888
    *  2. RGBA8888
    *  3. Luminance(gray-scale)8
    *  
    *  Terrain use TerrainData struct to initialize.the TerrainData struct warp 
    *  all parameters that Terrain initialization need.
    *  TerrainData provide several handy constructor for users
    *  
    * Surface detail is provided via texture splatting, where multiple Detail texture layers can be added
    * along with alpha map to define how different Detail texture blend with each other. These DetailTexture
    * can be defined in TerrainData. The number of supported Detail texture is Four. although typically 2-3 levels is
    * sufficient. For simple usage ,surface detail also is provided via simple Texture.
    * 
    * Internally, Terrain is divide into smaller, more manageable chunks, which can be culled
    * separately for more efficient rendering. The size of the terrain chunks can be controlled
    * via the chunkSize property in TerrainData.
    * 
    * Chunks are managed under the QuadTree.As DE FACTO terminal Node of the QuadTree;
    * let us cull chunks efficientlly to reduce drawCall amount And reduce the VBOs'Size that pass to the GPU.
    * 
    * Level of detail (LOD) is supported using a technique that is similar to texture mipmapping -- called GeoMapping.
    * A distance-to-camera based test used to decide
    * the appropriate LOD for a terrain chunk. The number of LOD levels is 0 by default (which
    * means only the base level is used),the maxium number of LOD levels is 4. Of course ,you can hack the value individually.
    * 
    * Finally, when LOD is enabled, cracks can begin to appear between terrain Chunks of
    * different LOD levels. An acceptable solution might be to simply reduce the lower LOD(high detail,smooth) chunks border,
    * And let the higher LOD(rough) chunks to seamlessly connect it.
    * 
    * We can use ray-terrain intersection to pick a point of the terrain;
    * Also we can get an arbitrary point of the terrain's height and normal vector for convenience .
    **/
class CC_DLL Terrain : public Node
{
public:

    /**the crack fix type. use to fix the gaps between different LOD chunks */
    enum class CrackFixedType{
        SKIRT,
        INCREASE_LOWER,
    };

   /**
    *DetailMap
    *this struct maintain a detail map data ,including source file ,detail size.
    *the DetailMap can use for terrain splatting
    **/
    struct CC_DLL DetailMap{
        /*Constructors*/
        DetailMap();
        DetailMap(const char * detailMapSrc, float size = 35);
        /*detail Image source file path*/
        std::string _detailMapSrc;
        /*detailMapSize determine how many tiles that Terrain represent*/
        float _detailMapSize;
    };

    /**
     * Triangle
     */
    struct Triangle
    {
        Triangle(Vec3 p1, Vec3 p2, Vec3 p3);
        bool getInsterctPoint(const Ray &ray, Vec3& interScetPoint) const;
        void transform(Mat4 matrix);
        Vec3 _p1, _p2, _p3;
    };


   /**
    *TerrainData
    *This TerrainData struct warp all parameter that Terrain need to create
    */
    struct CC_DLL TerrainData
    {
        /**empty constructor*/
        TerrainData();
        /**constructor, this constructor construct a simple terrain which only have 1 detailmap*/
        TerrainData(const char* heightMapsrc, const char * textureSrc, const Size & chunksize = Size(32,32), float mapHeight = 2, float mapScale = 0.1);
        /**constructor, this constructor construct a terrain which have 4 detailmaps, 1 alpha map*/
        TerrainData(const char* heightMapsrc, const char * alphamap, const DetailMap& detail1,const DetailMap& detail2, const DetailMap& detail3, const DetailMap& detail4, const Size & chunksize = Size(32,32), float mapHeight = 2, float mapScale = 0.1);
        /**constructor, this constructor construct a terrain which have 3 detailmaps, 1 alpha map*/
        TerrainData(const char* heightMapsrc, const char * alphamap, const DetailMap& detail1,const DetailMap& detail2, const DetailMap& detail3, const Size & chunksize = Size(32,32), float mapHeight = 2, float mapScale = 0.1);
        /**
        *deterimine the chunk size,chunk is the minimal subdivision of the Terrain
        */
        Size _chunkSize;
        /**height Map source path*/
        std::string _heightMapSrc;
        /**the source path of the alpha map*/
        char* _alphaMapSrc;
        /**detail maps*/
        DetailMap _detailMaps[4];
        /**terrain Maximum height*/
        float _mapHeight;
        /**terrain scale factor,you can combine setScale later.*/
        float _mapScale;
        /**the amount of detailmap*/
        int _detailMapAmount;
        /**the skirt height ratio, only effect when terrain use skirt to fix crack*/
        float _skirtHeightRatio;
    };
private:

    struct ChunkIndices
    {
        GLuint _indices;
        unsigned short _size;
    };

    struct ChunkLODIndices
    {
        int _relativeLod[5];
        ChunkIndices _chunkIndices;
    };


    struct ChunkLODIndicesSkirt
    {
        int _selfLod;
        ChunkIndices _chunkIndices;
    };
    /*
    *terrain vertices internal data format
    **/
    struct TerrainVertexData
    {
        /*constructor*/
        TerrainVertexData(){};
        TerrainVertexData(Vec3 v1, Tex2F v2)
        {
            _position = v1;
            _texcoord = v2;
        };
        /*the vertex's attributes*/
        cocos2d::Vec3 _position;
        cocos2d::Tex2F _texcoord;
        cocos2d::Vec3 _normal;
    };

    struct QuadTree;
    /*
    *the terminal node of quad, use to subdivision terrain mesh and LOD
    **/
    struct Chunk
    {
        /**Constructor*/
        Chunk();
        /**destructor*/
        ~Chunk();
        /*vertices*/
        std::vector<TerrainVertexData> _originalVertices;
        /*LOD indices*/
        struct LOD{
            std::vector<GLushort> _indices;
        };
        GLuint _vbo;
        ChunkIndices _chunkIndices; 
        /**we now support four levels of detail*/
        LOD _lod[4];
        /**AABB in local space*/
        AABB _aabb;
        /**setup Chunk data*/
        void generate(int map_width, int map_height, int m, int n, const unsigned char * data);
        /**calculateAABB*/
        void calculateAABB();
        /**internal use draw function*/
        void bindAndDraw();
        /**finish opengl setup*/
        void finish();
        /*use linear-sample vertices for LOD mesh*/
        void updateVerticesForLOD();
        /*updateIndices */
        void updateIndicesLOD();

        void updateIndicesLODSkirt();

        /**calculate the average slop of chunk*/
        void calculateSlope();

        bool getInsterctPointWithRay(const Ray& ray, Vec3 &interscetPoint);

        /**current LOD of the chunk*/
        int _currentLod;

        int _oldLod;

        int _neighborOldLOD[4];
        /*the left,right,front,back neighbors*/
        Chunk * _left;
        Chunk * _right;
        Chunk * _front;
        Chunk * _back;

        QuadTree * _parent;

        /**the position X in terrain space*/
        int _posX;
        /**the position Y in terrain space*/
        int _posY;
        /**parent terrain*/
        Terrain * _terrain;
        /**chunk size*/
        Size _size;
        /**chunk's estimated slope*/
        float _slope;
        std::vector<TerrainVertexData> _currentVertices;

        std::vector<Triangle> _trianglesList;
    };

   /**
    *QuadTree
    * @breif use to hierarchically frustum culling and set LOD
    **/
    struct QuadTree
    {
        /**constructor*/
        QuadTree(int x, int y, int width, int height, Terrain * terrain);
        /**destructor*/
        ~QuadTree();
        /**recursively draw*/
        void draw();
        /**recursively set itself and its children is need to draw*/
        void resetNeedDraw(bool value);
        /**recursively potential visible culling*/
        void cullByCamera(const Camera * camera, const Mat4 & worldTransform);
        /**precalculate the AABB(In world space) of each quad*/
        void preCalculateAABB(const Mat4 & worldTransform);
        QuadTree * _tl;
        QuadTree * _tr;
        QuadTree * _bl;
        QuadTree * _br;
        /**A flag present current quadTree node whether a terminal node,the terminal node is de facto the chunck*/
        bool _isTerminal;
        Chunk * _chunk;
        int _posX;
        int _posY;
        int _height;
        int _width;
        QuadTree * _parent;
        /**AABB's cache (in local space)*/
        AABB _localAABB;
        /**AABB's cache (in world space)*/
        AABB _worldSpaceAABB;
        Terrain * _terrain;
        /** a flag determine whether a quadTree node need draw*/
        bool _needDraw;
    };
    friend QuadTree;
    friend Chunk;
public:
    /*init function*/
    /**initialize all Properties which terrain need */
    bool initProperties();
    /**initialize heightMap data */
    bool initHeightMap(const char* heightMap);
    /**initialize alphaMap ,detailMaps textures*/
    bool initTextures();
    /**create entry*/
    static Terrain * create(TerrainData &parameter, CrackFixedType fixedType = CrackFixedType::INCREASE_LOWER);
    /**get specified position's height mapping to the terrain,use bi-linear interpolation method
     * @param x the X position
     * @param y the Z position
     * @param normal the specified position's normal vector in terrain . if this argument is NULL or nullptr,Normal calculation shall be skip.
     * @return the height value of the specified position of the terrain, if the (X,Z) position is out of the terrain bounds,it shall return 0;
     **/
    float getHeight(float x, float z, Vec3 * normal= nullptr) const;

    /**get specified position's height mapping to the terrain,use bi-linear interpolation method
     * @param pos the position (X,Z)
     * @param normal the specified position's normal vector in terrain . if this argument is NULL or nullptr,Normal calculation shall be skip.
     * @return the height value of the specified position of the terrain, if the (X,Z) position is out of the terrain bounds,it shall return 0;
     **/
    float getHeight(Vec2 pos, Vec3*Normal = nullptr) const;

    /**get the normal of the specified pistion in terrain
     * @return the normal vector of the specified position of the terrain.
     * @note the fast normal calculation may not get precise normal vector.
     **/
    Vec3 getNormal(int pixelX, int pixelY) const;
    /**get height from the raw height filed*/
    float getImageHeight(int pixelX, int pixelY) const;
    /**show the wireline instead of the surface,Debug Use only.
     * @Note only support desktop platform
     **/
    void setDrawWire(bool boolValue);
    /**
     * Set threshold distance of each LOD level,must equal or gereater than the chunk size
     * @Note when invoke initHeightMap, the LOD distance will be automatic calculated.
     */
    void setLODDistance(float lod1, float lod2, float lod3);

    /**Switch frustum Culling Flag
     * @Note frustum culling will remarkable improve your terrain rendering performance. 
     */
    void setIsEnableFrustumCull(bool boolValue);

    /** set the alpha map*/
    void setAlphaMap(cocos2d::Texture2D * newAlphaMapTexture);
    /**set the Detail Map */
    void setDetailMap(unsigned int index, DetailMap detailMap);

    // Overrides, internal use only
    virtual void draw(cocos2d::Renderer* renderer, const cocos2d::Mat4 &transform, uint32_t flags) override;
    /**
     * Ray-Terrain intersection.
     * @return the intersection point
     */
    Vec3 getIntersectionPoint(const Ray & ray) const;

   /**
    * Ray-Terrain intersection.
    * @param ray to hit the terrain
    * @param intersectionPoint hit point if hitted
    * @return true if hit, false otherwise
    */
    bool getIntersectionPoint(const Ray & ray, Vec3 & intersectionPoint) const;

    /**
     * set the MaxDetailAmount.
     */
    void setMaxDetailMapAmount(int maxValue);

    /**
     * Convert a world Space position (X,Z) to terrain space position (X,Z)
     */
    Vec2 convertToTerrainSpace(Vec2 worldSpace) const;

    /**
     * reset the heightmap data.
     */
    void resetHeightMap(const char * heightMap);

    /**
     * get the terrain's mininal height.
     */
    float getMinHeight();

    /**
     * get the terrain's maximum height.
     */
    float getMaxHeight();

    /**
     * get the terrain's AABB(in world space)
     */
    AABB getAABB();

    /**
     * set the skirt height ratio
     */
    void setSkirtHeightRatio(float ratio);

    /**
     * get the terrain's quad tree which is also the root node.
     */
    QuadTree * getQuadTree();

    void reload();
    
    /**
     * get the terrain's size
     */
    Size getTerrainSize() const { return Size(_imageWidth, _imageHeight); }
    
    /**
     * get the terrain's height data
     */
    std::vector<float> getHeightData() const;
    
protected:
    
    Terrain();
    virtual ~Terrain();
    void onDraw(const Mat4 &transform, uint32_t flags);

    /**
     * recursively set each chunk's LOD
     * @param cameraPos the camera postion in world space
     **/
    void setChunksLOD(Vec3 cameraPos);

    /**
     * load Vertices from height filed for the whole terrain.
     **/
    void loadVertices();

    /**
     * calculate Normal Line for each Vertex
     **/
    void calculateNormal();

    //override
    virtual void onEnter() override;

    /**
     * cache all unifrom loactions in GLSL.
     **/
    void cacheUniformAttribLocation();

    //IBO generate & cache
    ChunkIndices lookForIndicesLODSkrit(int selfLod, bool * result);

    ChunkIndices lookForIndicesLOD(int neighborLod[4], int selfLod, bool * result);

    ChunkIndices insertIndicesLOD(int neighborLod[4], int selfLod, GLushort * indices, int size);

    ChunkIndices insertIndicesLODSkirt(int selfLod, GLushort * indices, int size);
    
    Chunk * getChunkByIndex(int x,int y) const;

protected:
    std::vector <ChunkLODIndices> _chunkLodIndicesSet;
    std::vector<ChunkLODIndicesSkirt> _chunkLodIndicesSkirtSet;
    Mat4 _CameraMatrix;
    bool _isCameraViewChanged;
    TerrainData _terrainData;
    bool _isDrawWire;
    unsigned char * _data;
    float _lodDistance[3];
    Texture2D * _detailMapTextures[4];
    Texture2D * _alphaMap;
    CustomCommand _customCommand;
    QuadTree * _quadRoot;
    Chunk * _chunkesArray[MAX_CHUNKES][MAX_CHUNKES];
    std::vector<TerrainVertexData> _vertices;
    std::vector<GLushort> _indices;
    int _imageWidth;
    int _imageHeight;
    Size _chunkSize;
    bool _isEnableFrustumCull;
    int _maxDetailMapValue;
    cocos2d::Image * _heightMapImage;
    Mat4 _oldCameraModelMatrix;
    Mat4 _terrainModelMatrix;
    GLuint _normalLocation;
    GLuint _positionLocation;
    GLuint _texcordLocation;
    float _maxHeight;
    float _minHeight;
    CrackFixedType _crackFixedType;
    float _skirtRatio;
    int _skirtVerticesOffset[4];
    GLint _detailMapLocation[4];
    GLint _alphaMapLocation;
    GLint _alphaIsHasAlphaMapLocation;
    GLint _detailMapSizeLocation[4];

    RenderState::StateBlock* _stateBlock;

#if (CC_TARGET_PLATFORM == CC_PLATFORM_ANDROID || CC_TARGET_PLATFORM == CC_PLATFORM_WINRT)
    EventListenerCustom* _backToForegroundListener;
#endif
};

// end of actions group
/// @}

NS_CC_END
#endif